Test DIRECTORY
Explore our comprehensive menu of laboratory tests designed to support accurate, reliable results across every specialty.
APG LAB's test directory provides a comprehensive list of specialty and general laboratory testing services.
There are currently 38 names in this directory beginning with the letter T.
T-Cell Activation Profile, CD8 Subsets
Test Includes
Percentage and absolute values CD3+, CD3+CD4+, CD3+CD8+, CD3+CD25+, CD8+CD38+, CD8+HLA-DR+, CD4:CD8 ratio; CBC with differential
Expected Turnaround Time
1 - 3 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Specimen Requirements
Specimen
Whole blood
Volume
Fill tube(s) to capacity.
Container
Lavender-top (EDTA) tube and yellow-top (ACD-A) or (ACD-B) tube
Collection
Invert tube 8 to 10 times immediately after collection. To preserve cellular viability, collect specimen so it will arrive in the laboratory within 48 hours of collection. Indicate date and time of venipuncture on the tube(s) and on the test request form.
Storage Instructions
Maintain specimen at room temperature.
Stability Requirements
| Temperature | Period |
|---|---|
| Room temperature | 2 days |
| Refrigerated | Unstable |
| Frozen | Unstable |
| Freeze/thaw cycles | Unstable |
Causes for Rejection
Hemolysis; specimen refrigerated or frozen; clotted specimen; contaminated specimen
Test Details
Use
Expanded profile for AIDS monitoring and prognosis. An increase in activation markers is associated with poor prognosis.
Limitations
This test was developed, and its performance characteristics determined, by LabCorp. It has not been cleared or approved by the US Food and Drug Administration (FDA).
Methodology
Flow cytometry
Reference Interval
Reference intervals are established by the laboratory. See table.
| CD | 95% Confidence Interval | |||
|---|---|---|---|---|
| Percentage | Cells/mm3 | |||
| Minimum | Maximum | Minimum | Maximum | |
| CD3+ | 57.5 | 86.2 | 622 | 2402 |
| CD3+CD4+ | 30.8 | 58.5 | 359 | 1519 |
| CD3+CD8+ | 12.0 | 35.5 | 109 | 897 |
| CD3+CD25+ | 4.9 | 25.9 | 79 | 535 |
| T4:T8 ratio | 0.92 | 3.72 | ||
| CD8+CD38+ | 0 | 17.7 | 0 | 381 |
| CD8+HLA-DR+ | 0 | 4.9 | 0 | 117 |
T-Cell Receptor γ-Chain Gene Rearrangements
Special Instructions
Please direct any questions regarding this test to customer service at 800-345-4363.
Expected Turnaround Time
5 - 7 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Information
Specimen Requirements
Specimen
Whole blood, bone marrow, formalin-fixed, paraffin-embedded (FFPE) tissue block or slides, fresh or frozen tissue
Volume
3 to 5 mL whole blood, 1 mL bone marrow, five unstained slides at 10 uM or formalin-fixed, paraffin-embedded tissue block, tissue in RPMI or frozen
Minimum Volume
0.5 mL whole blood, 0.5 mL bone marrow, two unstained slides at 10uM
Container
Lavender-top (EDTA) tube, yellow-top (ACD) tube, green-top (heparin) tube, FFPE tissue block or slides, or tissue in RPMI or frozen
Collection
Fresh tissue should be placed in RPMI medium or shipped frozen on dry ice. Small samples (eg, punch biopsies, fine-needle aspirates) will also be accepted. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate specimens for each test requested.
Storage Instructions
Maintain whole blood/bone marrow or tissue in RPMI at 2°C to 8°C; FFPE specimens at room room temperature; frozen tissue at -80°C.
Causes for Rejection
Frozen whole blood/bone marrow; quantity not sufficient for analysis; tumor block containing no tumor tissue; broken or stained slides
Test Details
Use
This assay can be used to detect clonal T-cell receptor γ-chain gene rearrangements in blood, bone marrow, and tissue specimens. The presence of a monoclonal gene rearrangement usually, but not always, reflects the presence of a T-lymphocytic neoplasm, while polyclonal gene rearrangement patterns are found in benign reactive condition. Thus, the results of these studies can assist in the diagnosis of lymphoproliferative disorders.
Limitations
This PCR assay is able to detect a clonal DNA population at the sensitivity of 5% in a background of polyclonal DNA.
This test was developed, and its performance characteristics determined, by LabCorp. It has not been cleared or approved by the US Food and Drug Administration (FDA).
Methodology
Polymerase chain reaction (PCR)
T3 Uptake
Synonyms
- Thyroid Hormone-binding Ratio (THBR)
Special Instructions
This test reflects assessment of thyroxine-binding globulin (TBG) and should not be ordered alone.
This test may exhibit interference when sample is collected from a person who is consuming a supplement with a high dose of biotin (also termed as vitamin B7 or B8, vitamin H, or coenzyme R). It is recommended to ask all patients who may be indicated for this test about biotin supplementation. Patients should be cautioned to stop biotin consumption at least 72 hours prior to the collection of a sample.
Expected Turnaround Time
Within 1 day
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Information
Related Documents
Specimen Requirements
Specimen
Serum
Volume
1 mL (adult), 0.8 mL (pediatric)
Minimum Volume
0.5 mL (adult), 0.3 mL (pediatric) (Note: This volume does not allow for repeat testing.)
Container
Red-top tube or gel-barrier tube
Collection
If a red-top tube is used, transfer separated serum to a plastic transport tube.
Storage Instructions
Room temperature
Stability Requirements
| Temperature | Period |
|---|---|
| Room temperature | 14 days |
| Refrigerated | 14 days |
| Frozen | 14 days |
| Freeze/thaw cycles | Stable x3 |
Test Details
Use
Thyroid function test for the diagnosis of hypothyroidism or hyperthyroidism, used with thyroxine (T4) or equivalent to provide free T4 index, FTI. An indirect measure of binding protein, the T3 uptake reflects available binding sites (ie, reflects TBG). T3 uptake is not a measurement of serum T3. It should never be used alone; rather, its usual application is use with thyroxine (T4).
Limitations
Alterations in binding capacity of TBG are described with major illness and with high doses of salicylates and corticosteroids; with use of heroin, methadone, phenytoin, and perphenazine. Alterations occur with malnutrition, such as in metastatic malignancy, and are found in patients with abnormal serum protein patterns (eg, nephrotic syndromes, cirrhosis). Other states in which changes in TBG occur include infancy, acromegaly, molar and ordinary pregnancy, oral contraceptives, and with exogenous hormones including androgens, anabolic steroids, and estrogens. Hereditary increase and decrease of TBG occurs.
Methodology
Electrochemiluminescence Immunoassay (ECLIA)
Reference Interval
See table.1
| Age | Male (%) | Female (%) |
|---|---|---|
| 0 to 11 m | 23−34 | 23−36 |
| 1 to 3 y | 24−35 | 24−36 |
| 4 to 6 y | 24−34 | 24−35 |
| 7 to 11 y | 24−33 | 22−35 |
| 12 to 15 y | 25−37 | 23−37 |
| 16 to 18 y | 24−38 | 23−35 |
| >18 y | 24−39 | 24−39 |
Tacrolimus, Immunoassay
Synonyms
- FK506
- Prograf®
- Protopic®
Special Instructions
If the preferred methodology for tacrolimus is liquid chromatography/tandem mass spectrometry (LC/MS-MS), please order test 700248.
Expected Turnaround Time
1 - 4 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Specimen Requirements
Specimen
Whole blood
Volume
1 mL
Minimum Volume
0.3 mL
Container
Lavender-top (EDTA) tube
Collection
Specimens collected in EDTA tubes may be stored for seven days at 2°C to 8°C prior to being tested.
Storage Instructions
Room temperature
Stability Requirements
| Temperature | Period |
|---|---|
| Room temperature | 7 days |
| Refrigerated | 7 days |
| Frozen | 2 months |
Causes for Rejection
Plasma or serum specimen
Test Details
Use
Tacrolimus is an immunosuppressive drug that is believed to prevent rejection in transplantation patients. Measurement of tacrolimus blood levels may be of use in monitoring patients receiving this drug.
Limitations
Patient samples may contain heterophilic antibodies that could react in immunoassays to give falsely elevated or depressed results. Antibodies to β-galactosidase can be encountered in samples as a consequence of bacterial infection and may produce falsely elevated results that may not be consistent with clinical evaluation.
Methodology
Microgenics QMS immunoassay
Additional Information
Tacrolimus is an immunosuppressive drug that is believed to prevent rejection in transplantation patients. Measurement of tacrolimus blood levels may be of use in monitoring patients receiving this drug. Tacrolimus, previously known as FK506, is an immunosuppressive drug derived from the bacterium Streptomyces tsukubaensis. It has been shown to be effective for the treatment of rejection following liver and kidney transplantations. Clinical trials are continuing for a variety of indications. Tacrolimus inhibits T-lymphocyte activation by inhibition of the phosphate activity of calcineurin, although the exact mechanism of action is not known. Tacrolimus is bound to plasma proteins and is highly bound to erythrocytes (ration of whole blood:plasma ranging from 12−67). Tacrolimus may be administered IV or orally. Absorption from the GI tract is variable and irregular. Peak blood concentrations are achieved at 1.5 to 3.5 hours. The elimination half-life from whole blood is 11.7 hours in transplant patients. Tacrolimus can cause nephrotoxicity, particularly when used in high doses. Care must be taken if tacrolimus is used in combination with other immunosuppressive drugs, particularly cyclosporine. Drugs found to increase tacrolimus levels include diltiazem, verapamil, clotrimazole, fluconazole, ketoconazole, voriconazole, clarithromycin, erythromycin, nelfinavir, torinavir, as well as grapefruit juice. Decreased tacrolimus levels have been found with coadministration of rifampicin, phenytoin, carbamazepine, phenobarbital, octreotide, and St John's wort.1
Tacrolimus, Whole Blood
Synonyms
- Antistriated Muscle Antibodies
Expected Turnaround Time
2 - 4 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Documents
Specimen Requirements
Specimen
Serum
Volume
0.4 mL
Minimum Volume
0.2 mL
Container
Red-top tube or gel-barrier tube
Storage Instructions
Maintain specimen at room temperature.
Stability Requirements
| Temperature | Period |
|---|---|
| Room temperature | 14 days |
| Refrigerated | 14 days |
| Frozen | 14 days |
| Freeze/thaw cycles | Stable x3 |
Causes for Rejection
Hemolyzed or lipemic serum
Test Details
Use
Diagnose myasthenia gravis and thymoma
Methodology
Indirect fluorescent antibody (IFA)
Reference Interval
Negative: <1:40
Additional Information
Striational antibodies are detectable in 80% to 100% of patients who have myasthenia gravis and thymoma. Measurement of acetylcholine receptor antibodies and striational antibodies is useful for predicting risk of myasthenia gravis in patients with thymoma.
Tangerine
Expected Turnaround Time
3 - 4 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Information
Related Documents
Specimen Requirements
Specimen
Serum
Volume
0.2 mL
Container
Red-top tube or gel-barrier tube
Storage Instructions
Room temperature
Stability Requirements
| Temperature | Period |
|---|---|
| Room temperature | 14 days |
| Refrigerated | 14 days |
| Frozen | 3 months |
| Freeze/thaw cycles | Stable x3 |
Test Details
Methodology
Thermo Fisher ImmunoCAP®
Tapentadol, Confirmation, Urine
Synonyms
- Nucynta®
Special Instructions
This profile is designed for pain management. It is not intended for workplace testing and does not comply with state regulatory workplace testing programs.
Expected Turnaround Time
4 - 5 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Specimen Requirements
Specimen
Urine
Volume
20 mL
Minimum Volume
3 mL
Container
Plastic urine container
Collection
Urine temperature monitoring is recommended to ensure valid specimen collection.
Storage Instructions
Maintain specimen at room temperature. If arrival at lab will extend beyond seven days, refrigerate.
Causes for Rejection
Quantity not sufficient for analysis; improper specimen (serum, plasma, blood); incomplete specimen identification
Test Details
Use
Confirm the presence of tapentadol
Methodology
Mass spectrometry (MS)
Tapentadol, Serum or Plasma
Synonyms
- Nucynta®
Expected Turnaround Time
7 - 10 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Specimen Requirements
Specimen
Serum or plasma
Volume
3 mL
Minimum Volume
1 mL
Container
Red-top tube or green-top (heparin) tube. Gel-barrier tubes are not recommended.
Collection
Serum or plasma should be separated from cells within two hours of venipuncture. Submit serum or plasma in a plastic transport tube.
Storage Instructions
Submission/transport (<3 days): Room temperature. For storage beyond three days, specimen should be refrigerated or frozen.
Patient Preparation
Trough levels are most reproducible.
Causes for Rejection
Gel-barrier tubes
Test Details
Use
Therapeutic drug management.
Methodology
Liquid chromatography/tandem mass spectrometry (LC/MS-MS)
Tay-Sachs Disease, DNA Analysis
Synonyms
- Hexosaminidase A Deficiency
Special Instructions
A completed screening questionnaire must accompany specimens. Call 800-345-4363 to request forms, or photocopy the Tay-Sachs Disease Screening Questionnaire from the Genetics Appendix online.
If cultured cells are needed, an additional 7-12 days may be required. Additional culture fee may be included.
Expected Turnaround Time
8 - 14 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Information
Related Documents
For more information, please view the literature below.
Tay-Sachs Disease Screening Questionnaire
Specimen Requirements
Specimen
Whole blood, amniotic fluid, chorionic villus sample (CVS) (submission of maternal blood is required for fetal testing), or LabCorp buccal swab kit (buccal swab collection kit contains instructions for use of a buccal swab)
Volume
7 mL whole blood, 10 mL amniotic fluid, 20 mg CVS, or LabCorp buccal swab kit
Minimum Volume
3 mL whole blood, 5 mL amniotic fluid, 10 mg CVS, or two buccal swabs
Container
Lavender-top (EDTA) tube, yellow-top (ACD) tube, sterile plastic conical tube or two confluent T25 flasks for fetal testing, or LabCorp buccal swab kit
Storage Instructions
Maintain specimen at room temperature.
Causes for Rejection
Frozen specimen; hemolysis; quantity not sufficient for analysis; improper container; one buccal swab; wet buccal swab
Test Details
Use
Pre- and postnatal determination of Tay-Sachs disease carrier status; resolution of pseudodeficiency allele status
Limitations
More than 95% of the mutant alleles in persons with Ashkenazi Jewish heritage are detected. In persons with French-Canadian ancestry, 80% of the mutations are detected, and 25% of mutations in non-Jewish Caucasians are also detected.
Methodology
Polymerase chain reaction (PCR); primer extension; flow-sorted bead array analysis for five mutations and two pseudodeficiency alleles in the hexosaminidase A gene
Additional Information
Tay-Sachs disease is an autosomal recessive lysosomal storage disorder that causes progressive neurological deterioration ranging in severity from forms with infantile onset to those with adult onset. If the individual tested by DNA analysis is not of Ashkenazi Jewish descent, carrier testing by enzyme analysis is strongly recommended. Couples who are both carriers have a one in four risk of having a child with Tay-Sachs disease. DNA test results should be combined with enzyme test results and clinical information for the most accurate interpretation. The mutations tested include: 1278insTATC, G269S, IVS9+1 G>A, 1421+1 G>C, and 7.6 kb deletion. Pseudodeficiency alleles tested include: R247W and R249W.
Note: The pseudodeficiency mutation, R247W, accounts for 32% of enzyme-defined carriers in the non-Jewish population, while R249W accounts for 4% of pseudodeficiency among Ashkenazi Jews. These mutations affect the enzyme test, but do not affect in vivo function of beta-hexosaminidase A. Carriers of these mutations are not at increased risk to have children with Tay-Sachs disease.
Temazepam, Serum or Plasma
Synonyms
- Restoril®
Expected Turnaround Time
5 - 10 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Specimen Requirements
Specimen
Serum or plasma
Volume
2 mL
Minimum Volume
0.5 mL
Container
Red-top tube or green-top (heparin) tube. Gel-barrier tubes are not recommended.
Collection
Serum or plasma should be separated from cells within two hours of venipuncture. Submit serum or plasma in a plastic transport tube.
Storage Instructions
Submission/transport (<3 days): Room temperature. For storage beyond three days, specimen should be refrigerated or frozen.
Patient Preparation
Trough levels are most reproducible.
Causes for Rejection
Gel-barrier tubes
Test Details
Use
Therapeutic drug management
Methodology
High-pressure liquid chromatography with ultraviolet detection (HPLC/UV)
Reference Interval
50−1000 ng/mL
Testicular Function Profile I
Test Includes
Follicle-stimulating hormone (FSH); luteinizing hormone (LH); prolactin; testosterone, total
Special Instructions
Indicate patient's age on the request form.
This test may exhibit interference when sample is collected from a person who is consuming a supplement with a high dose of biotin (also termed as vitamin B7 or B8, vitamin H, or coenzyme R). It is recommended to ask all patients who may be indicated for this test about biotin supplementation. Patients should be cautioned to stop biotin consumption at least 72 hours prior to the collection of a sample.
Expected Turnaround Time
Within 1 day
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Documents
Specimen Requirements
Specimen
Serum
Volume
1.5 mL
Minimum Volume
0.8 mL (Note: This volume does not allow for repeat testing.)
Container
Red-top tube or gel-barrier tube
Collection
If a red-top tube is used, transfer separated serum to a plastic transport tube.
Storage Instructions
Refrigerate
Stability Requirements
| Temperature | Period |
|---|---|
| Room temperature | 3 days |
| Refrigerated | 5 days |
| Frozen | 14 days |
| Freeze/thaw cycles | Stable x3 |
Test Details
Methodology
Electrochemiluminescence immunoassay (ECLIA)
Testicular Function Profile II
Test Includes
Follicle-stimulating hormone (FSH); luteinizing hormone (LH); testosterone, total and free
Special Instructions
This test may exhibit interference when sample is collected from a person who is consuming a supplement with a high dose of biotin (also termed as vitamin B7 or B8, vitamin H, or coenzyme R). It is recommended to ask all patients who may be indicated for this test about biotin supplementation. Patients should be cautioned to stop biotin consumption at least 72 hours prior to the collection of a sample.
Expected Turnaround Time
3 - 5 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Documents
Specimen Requirements
Specimen
Serum
Volume
3 mL
Minimum Volume
1.5 mL (Note: This volume does not allow for repeat testing.)
Container
Red-top tube or gel-barrier tube
Collection
If a red-top tube is used, transfer separated serum to a plastic transport tube.
Storage Instructions
Refrigerate
Stability Requirements
| Temperature | Period |
|---|---|
| Room temperature | 14 days |
| Refrigerated | 14 days |
| Frozen | 14 days |
| Freeze/thaw cycles | Stable x3 |
Testosterone, Total
Special Instructions
This test may exhibit interference when sample is collected from a person who is consuming a supplement with a high dose of biotin (also termed as vitamin B7 or B8, vitamin H, or coenzyme R). It is recommended to ask all patients who may be indicated for this test about biotin supplementation. Patients should be cautioned to stop biotin consumption at least 72 hours prior to the collection of a sample.
Expected Turnaround Time
Within 1 day
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Information
Related Documents
For more information, please view the literature below.
Laboratory Update: Testosterone Reference Interval Change for Adult Males
Q&A: Testosterone Reference Interval Changes (Adult Males)
Specimen Requirements
Specimen
Serum
Volume
0.8 mL
Minimum Volume
0.3 mL (Note: This volume does not allow for repeat testing.)
Container
Red-top tube or gel-barrier tube
Collection
If a red-top tube is used, transfer separated serum to a plastic transport tube.
Storage Instructions
Room temperature
Stability Requirements
| Temperature | Period |
|---|---|
| Room temperature | 14 days |
| Refrigerated | 14 days |
| Frozen | 14 days |
| Freeze/thaw cycles | Stable x3 |
Causes for Rejection
Citrate plasma specimen; improper labeling
Test Details
Use
Testosterone testing is used to evaluate androgen excess or deficiency related to gonadal function, adrenal function, or tumor activity. Testosterone levels may be helpful in men for the diagnosis of hypogonadism, hypopituitarism, Klinefelter syndrome, and impotence (low values). Testosterone levels may be requested in women to investigate the cause of hirsutism, anovulation, amenorrhea, virilization, masculinizing tumors of the ovary, tumors of the adrenal cortices, and congenital adrenal hyperplasia (high values). Testosterone levels in children may be helpful to investigate issues related to puberty and development as well as the aforementioned. For testosterone measurements in females and children, use of Testosterone, Total, Women, Children, and Hypogonadal Males, LC/MS-MS [070001], which employs liquid chromatography/tandem mass spectrometry (LC/MS-MS), is recommended.
Limitations
As with all tests containing monoclonal mouse antibodies, erroneous findings may be obtained from samples taken from patients who have been treated with monoclonal mouse antibodies or have received them for diagnostic purposes.1 In rare cases, interference due to extremely high titers of antibodies to streptavidin and ruthenium can occur.1 The test contains additives, which minimize these effects.
Methodology
Electrochemiluminescence immunoassay (ECLIA)
Reference Interval
See table.
| Tanner Stage | Male | Female |
|---|---|---|
| Testosterone (ng/dL) | Testosterone (ng/dL) | |
| I | <3 | <3−6 |
| II | <3−432 | <3−10 |
| III | 65−778 | <3−24 |
| IV | 180−763 | <3-27 |
| V | 188−882 | 5−38 |
| Adult Male | Adult Female | |
| >18 y: 264-916 | 20 to 49 y: 8−48 | |
| >49 y: 3−41 |
Additional Information
This immunoassay is intended for the in vitro quantitative determination of testosterone in human serum and plasma.
Testosterone is the principal androgen in men.2,3 The production of testosterone by the male testes is stimulated by luteinizing hormone (LH), which is produced by the pituitary. LH secretion is, in turn, inhibited through a negative feedback loop by increased concentrations of testosterone and its metabolites. Most of the testosterone in males is produced by the Leydig cells of the testes and is secreted into the seminiferous tubule, where it is complexed to a protein made by the Sertoli cells. This results in the high local levels of testosterone that are required for normal sperm production.
Diminished testosterone production is one of many potential causes of infertility in males.3,4 Low testosterone concentrations can be caused by testicular failure (primary hypogonadism) or inadequate stimulation by pituitary gonadotropins (secondary hypogonadism). Since men with hypogonadism often have high SHBG levels, the measurement of free or bioavailable testosterone has been advocated when total testosterone levels are normal in men with symptoms of androgen deficiency.5 Significant physiological changes occur in men as they age, in part due to a gradual decline in testosterone levels.6,7 It is generally accepted that the principal cause of this age-related decrease in testosterone production is testicular failure, although diminished gonadotropin production may play a role.5 By 75 years of age, the average male testosterone drops to 65% of average level in young adults. “Andropause” is a term that has been used to refer to the constellation of symptoms associated with the age-related decline in testosterone production in men.5,8 The adult male reference range for testosterone was established by Travison and coworkers through an epidemiologic study that included men from different geographic regions of the United States and Europe.9 Testosterone measurment was harmonized to the Center for Disease Control reference method.9 The reference population included only men younger than 40 years of age who had a BMI less than 30. Much smaller amounts of testosterone and dihydrotestosterone are produced in women than in men.2,3 Weaker adrenal androgens and ovarian precursor molecules including androstenedione, DHEA, and DHEA sulfate can have significant androgenic effects in women. The ovary and adrenal glands produce some testosterone, but the majority of the testosterone in women is derived from the peripheral conversion of other steroids. Often, the first sign of testosterone excess in women is the development of male pattern hair growth, which is referred to as hirsutism.1,3,4,10 It should be noted that some women experience hair growth similar to that caused by increased testosterone due to racial or genetic causes and not due to excessive androgens. Measurement of the testosterone may help to distinguish racial or genetic causes of hirsutism from the abnormal pathology, particularly in women with mixed ethnic backgrounds. Women with more excessive testosterone levels may also experience virilization, with symptoms including increased muscle mass, redistribution of body fat, enlargement of the clitoris, deepening of the voice, and acne and increased perspiration. These women can also suffer from androgenic alopecia, the female equivalent of male pattern baldness.
Many women with slowly progressive androgenic symptoms are diagnosed as having polycystic ovary syndrome (PCOS).10-12 PCOS is relatively common, affecting approximately 6% of women of reproductive age.6 Women with this complex syndrome experience symptoms of androgen excess associated with menstrual abnormalities and infertility. Most women with the syndrome have polycystic ovaries that can be detected by ultrasonography, although this finding is not essential for diagnosis.3,4,13 Chronic anovulation experienced by patients with PCOS increases their risk of developing endometrial cancer. Women with PCOS are often overweight and are likely to suffer from insulin resistance putting them at increased risk for developing type 2 diabetes mellitus.2,11 Obesity and insulin resistance can result in acanthosis nigricans, a skin condition that is characterized by hyperpigmented, velvety plaques of body folds.2 Lipid abnormalities, including decreased high-density lipoprotein cholesterol levels and elevated triglyceride levels as well as impaired fibrinolysis, are seen in women with PCOS.11 Cardiovascular disease is more prevalent, and women with PCOS have a significantly increased risk for myocardial infarction.11
Tetanus/Diphtheria Antibody Profile
Test Includes
Diphtheria antitoxoid antibodies; tetanus antitoxoid antibodies
Expected Turnaround Time
2 - 6 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Documents
Specimen Requirements
Specimen
Serum
Volume
1 mL
Minimum Volume
0.5 mL
Container
Red-top tube or gel-barrier tube
Storage Instructions
Room temperature
Stability Requirements
| Temperature | Period |
|---|---|
| Room temperature | 14 days |
| Refrigerated | 14 days |
| Frozen | Unstable |
Test Details
Limitations
This procedure may be considered by Medicare and other carriers as investigational and, therefore, may not be payable as a covered benefit for patients.
Methodology
Enzyme immunoassay (EIA)
Reference Interval
• Nonprotective: <0.10 IU/mL
• Protective: ≥0.10 IU/mL
Tetrahydrocannabinol (THC), Screen Only, Whole Blood
Expected Turnaround Time
3 - 5 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Specimen Requirements
Specimen
Whole blood
Volume
7 mL
Minimum Volume
3 mL
Container
Lavender-top (EDTA) tube, gray-top (sodium fluoride) tube, or green-top (heparin) tube
Storage Instructions
Submission/transport (<3 days): Room temperature. For storage beyond three days, specimen should be refrigerated or frozen.
Test Details
Use
Detect presumptive presence of tetrahydrocannabinol (THC)
Methodology
Presumptive testing by immunoassay (IA) at a testing threshold of 5 ng/mL. Presumptive positives are not confirmed by a definitive method.
Thermoactinomyces sacchari Precipitating Antibodies, IgG
Synonyms
- Bagassosis
- Hypersensitivity Pneumonitis
- Malt-worker's Lung
Expected Turnaround Time
4 - 5 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Information
Related Documents
For more information, please view the literature below.
Allergy Services: Identify and Manage Patients With Allergic Disease
Allergy Test Menu
Specimen Requirements
Specimen
Serum
Volume
1 mL
Container
Red-top tube or gel-barrier tube
Storage Instructions
Room temperature
Causes for Rejection
Excessive hemolysis
Test Details
Use
Confirm the presence of precipitating antibodies to Thermoactinomyces sacchari
Limitations
A positive test does not establish the diagnosis of hypersensitivity pneumonitis, nor does the absence of precipitins eliminate the diagnosis.
Methodology
Double diffusion (Ouchterlony)
Reference Interval
Normal: negative
Additional Information
Hypersensitivity pneumonitis (HP), also referred to as extrinsic allergic alveolitis (EAA), is an inflammatory lung disease resulting from the inhalation and subsequent sensitization to a wide variety of inhaled organic dusts.1-5 Exposure to Thermoactinomyces sacchari can result from contact with moldy sugar cane causing a condition referred to as malt worker's lung or bagassosis1-3 HP is not mediated by IgE. It is associated with progressive pulmonary disability, irreversible lung damage, and mortality in some occupational settings.1-5 Patients often present with intermittent chills, fever, cough, and shortness of breath that begin four to eight hours after exposure to the offending dust.
No single laboratory test is diagnostic for hypersensitivity pneumonitis.1-5 Diagnosis is based on a complete environmental history supported by result of chest x-ray, spirometry, and in vitro immunologic tests.1-5 Identification of the causative agent is important to allow avoidance of exposure.2,5 Double diffusion (Ouchterlony) assays are typically used to determine antigen-specific IgG antibodies.5 The appearance of precipitin arcs confirms the presence of precipitating antibodies to specific antigens. These antibodies may also be present in individuals not afflicted with HP.2,3,5 The presence of antibodies to the offending dust or antigen confirms exposure but is not diagnostic of HP; however, upon repeated or prolonged exposures, high levels of precipitating IgG antibodies are typically observed.
Thiopurine Metabolites
Synonyms
- 6MP Metabolites
- 6TG Metabolites
- Azathioprine Metabolites
- Mercaptopurine Metabolites
Expected Turnaround Time
6 - 12 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Documents
For more information, please view the literature below.
Rheumatoid Arthritis
Specimen Requirements
Specimen
Whole blood
Volume
3 mL
Minimum Volume
1 mL (Note: This volume does not allow for repeat testing.)
Container
Lavender-top (EDTA) tube
Collection
Collect blood in lavender-top (EDTA) tube only. Gently invert to mix. Submit whole blood refrigerated. Do not separate specimen. Do not freeze.
Storage Instructions
Refrigerate
Stability Requirements
| Temperature | Period |
|---|---|
| Room temperature | 1 day |
| Refrigerated | 8 days |
| Frozen | unstable |
Causes for Rejection
Frozen specimen; specimen not EDTA whole blood; gross hemolysis
Test Details
Use
This assay measures the red-cell concentration of 6-MMP (formed from 6-MP by thiopurine methyltransferase) and also measures the concentration of the resulting 6-TG after removal of the mono-, di-, or tri-phosphates from the various 6-thioguanine nucleotides. Once thiopurine therapy has been undertaken and an equilibrated drug level is achieved (usually three to six months), literature suggests that the measurement of thiopurine metabolites is warranted in the following situations:
1. Unresponsive patients to rule out (a) patient noncompliance (low 6-MMP and low 6-TG in those not taking medications), (b) those with diversion of metabolites away from 6-TG production (low 6-TG and normal or increased 6-MMP), (c) those with refractory to treatment (adequate 6-TG but lack of clinical response), and (d), those with excessive 6-MMP (or increased 6-MMP:6-TG ratio with adequate 6-TG) leading to increased hepatotoxicity.
2. Clinically responsive patients to look for excessive levels of either 6-MMP or 6-TG to avoid toxicity.
Limitations
This test should only be performed for patients currently on thiopurine therapy. This therapy includes administration of azathioprine or mercaptopurine. This test may not be useful in patients with autoimmune hepatitis.
Methodology
Whole blood washing and red blood cell harvesting/counting. Liquid chromatography/tandem mass spectrometry (LC/MS-MS) after acidic hydrolysis.
Reference Interval
See table.
| *Chevaux JB, Peyrin-Biroulet L, Sparrow MP. Optimizing thiopurine therapy in inflammatory bowel disease. Inflamm Bowel Dis. 2011 Jun; 17(6):1428-1435. |
Thrombosis, Venous Risk Profile
Test Includes
Anticardiolipin antibodies, IgG and IgM; antithrombin activity; β2-glycoprotein 1 antibodies, IgA, IgG, and IgM; D-dimer; dRVVT screen; factor II (prothrombin) mutation analysis; factor V Leiden mutation analysis; protein C, functional; protein S antigen, free
Expected Turnaround Time
4 - 10 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Information
Related Documents
Specimen Requirements
Specimen
Plasma, frozen and serum, refrigerated, and whole blood or buccal swab kit (Buccal swab collection kit contains instructions for the use of a buccal swab.)
Volume
6 mL frozen plasma (3 mL in each of two tubes) and 2 mL serum and 7 mL whole blood or LabCorp buccal swab kit
Minimum Volume
3 mL frozen plasma and 0.5 mL serum and 3 mL whole blood or two buccal swabs
Container
Blue-top (sodium citrate) tube, gel-barrier tube, lavender-top (EDTA) tube, yellow-top (ACD) tube, or LabCorp buccal swab kit
Collection
Citrated plasma samples should be collected by double centrifugation. Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate.1 Evacuated collection tubes must be filled to completion to ensure a proper blood-to-anticoagulant ratio.2,3 The sample should be mixed immediately by gentle inversion at least six times to ensure adequate mixing of the anticoagulant with the blood. A discard tube is not required prior to collection of coagulation samples.4,5 When noncitrate tubes are collected for other tests, collect sterile and nonadditive (red-top) tubes prior to citrate (blue-top) tubes. Any tube containing an alternate anticoagulant should be collected after the blue-top tube. Gel-barrier tubes and serum tubes with clot initiators should also be collected after the citrate tubes. Centrifuge for 10 minutes and carefully remove 2/3 of the plasma using a plastic transfer pipette, being careful not to disturb the cells. Deliver to a plastic transport tube, cap, and recentrifuge for 10 minutes. Use a second plastic pipette to remove the plasma, staying clear of the platelets at the bottom of the tube. Transfer the plasma into a LabCorp PP transpak frozen purple tube with screw cap (LabCorp N° 49482). Freeze immediately and maintain frozen until tested. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.
Please print and use the Volume Guide for Coagulation Testing to ensure proper draw volume.
Storage Instructions
Freeze plasma. Refrigerate serum. Maintain whole blood and buccal swab kit at room temperature or refrigerate.
Patient Preparation
Do not draw from an arm with a heparin lock or heparinized catheter.
Test Details
Methodology
See individual tests.
Thrombotic Risk Profile I
Test Includes
Activated protein C resistance (APCR) with reflex to factor V Leiden mutation analysis; anticardiolipin antibodies (ACA), quantitative, IgG, IgM; antithrombin activity; β2-glycoprotein 1 antibodies, IgG, IgM; dilute prothrombin time; factor II (prothrombin), DNA analysis; homocyst(e)ine, plasma; lupus anticoagulant with reflex; plasminogen activity; protein C, functional; protein S, free
Special Instructions
Note: If the Activated Protein C Resistance (APCR) [117762] result is <2.0, it will reflex to Factor V Leiden Mutation Analysis [511154] at an additional charge.
Expected Turnaround Time
4 - 10 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Information
- Acquired Thrombophilia
- Anticardiolipin Antibodies
- Anticardiolipin Antibodies (ACA), IgA, IgG, IgM, Quantitative
- Antithrombin (AT) Activity
- Dilute Prothrombin Time
- Factor II (Prothrombin), DNA Analysis
- Genetic Thrombophilia
- Homocyst(e)ine
- Lupus Anticoagulant With Reflex
- Plasminogen Activity
- Protein C, Functional
- Thrombophilia
- β2-Glycoprotein 1 Antibodies, IgA, IgG, IgM
Related Documents
For more information, please view the literature below.
Procedures for Hemostasis and Thrombosis: A Clinical Test Compendium
Specimen Requirements
Specimen
Plasma, frozen, and serum, refrigerated, and whole blood or buccal swab kit (buccal swab collection kit contains instructions for the use of a buccal swab)
Volume
2 mL frozen sodium citrate plasma and 1 mL serum and 7 mL whole blood or buccal swab
Container
Blue-top (sodium citrate) tube, gel-barrier tube, lavender-top (EDTA) tube, yellow-top (ACD) tube, or LabCorp buccal swab kit
Collection
Citrated plasma samples should be collected by double centrifugation. Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate.1 Evacuated collection tubes must be filled to completion to ensure a proper blood to anticoagulant ratio.2,3 The sample should be mixed immediately by gentle inversion at least six times to ensure adequate mixing of the anticoagulant with the blood. A discard tube is not required prior to collection of coagulation samples, except when using a winged blood collection device (ie, "butterfly"), in which case a discard tube should be used.4,5 When noncitrate tubes are collected for other tests, collect sterile and nonadditive (red-top) tubes prior to citrate (blue-top) tubes. Any tube containing an alternate anticoagulant should be collected after the blue-top tubes. Gel-barrier tubes and serum tubes with clot initiators should also be collected after the citrate tubes. Centrifuge for 10 minutes and (using a plastic transfer pipette) carefully remove two-thirds of the plasma without disturbing the cells. Deliver to a plastic transfer tube, cap, and recentrifuge for 10 minutes. Use a second plastic pipette to remove the plasma, staying clear of the platelets at the bottom of the tube. Transfer the plasma into a LabCorp PP transpak frozen purple tube with screw cap (LabCorp N° 49482). The specimen should be frozen immediately and maintained frozen until tested. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.
Please print and use the Volume Guide for Coagulation Testing to ensure proper draw volume.
Storage Instructions
Freeze plasma. Refrigerate serum. Maintain whole blood and buccal swab kit at room temperature or refrigerate.
Patient Preparation
Do not draw from an arm with a heparin lock or a heparinized catheter.
Thyroid Profile II, Comprehensive
Synonyms
- Thyroid Profile D (Comprehensive)
Test Includes
Free thyroxine index (FTI); T3 uptake (THBR); thyroid-stimulating hormone (TSH); thyroxine (T4); tri-iodothyronine (T3)
Special Instructions
This test may exhibit interference when sample is collected from a person who is consuming a supplement with a high dose of biotin (also termed as vitamin B7 or B8, vitamin H, or coenzyme R). It is recommended to ask all patients who may be indicated for this test about biotin supplementation. Patients should be cautioned to stop biotin consumption at least 72 hours prior to the collection of a sample.
Expected Turnaround Time
Within 1 day
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Documents
For more information, please view the literature below.
Thyroid Cascade Testing: Differential Laboratory Diagnosis of Thyroid Function
Specimen Requirements
Specimen
Serum
Volume
2.5 mL
Minimum Volume
1.5 mL (Note: This volume does not allow for repeat testing.)
Container
Red-top tube or gel-barrier tube
Collection
If a red-top tube is used, transfer separated serum to a plastic transport tube.
Storage Instructions
Refrigerate
Stability Requirements
| Temperature | Period |
|---|---|
| Room temperature | 14 days |
| Refrigerated | 14 days |
| Frozen | 14 days |
| Freeze/thaw cycles | Stable x3 |
Causes for Rejection
Plasma specimen
Test Details
Methodology
See individual tests.
Thyroid-stimulating Hormone (TSH)
Synonyms
- Third-generation TSH
- Thyrotropin
Special Instructions
This test may exhibit interference when sample is collected from a person who is consuming a supplement with a high dose of biotin (also termed as vitamin B7 or B8, vitamin H, or coenzyme R). It is recommended to ask all patients who may be indicated for this test about biotin supplementation. Patients should be cautioned to stop biotin consumption at least 72 hours prior to the collection of a sample.
Expected Turnaround Time
Within 1 day
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Documents
For more information, please view the literature below.
Thyroid Testing: Assessing Thyroid Disease in Your Patients
TSH Testing at LabCorp
Specimen Requirements
Specimen
Serum
Volume
0.8 mL
Minimum Volume
0.3 mL (Note: This volume does not allow for repeat testing.)
Container
Red-top tube or gel-barrier tube
Collection
If a red-top tube is used, transfer separated serum to a plastic transport tube.
Storage Instructions
Room temperature
Stability Requirements
| Temperature | Period |
|---|---|
| Room temperature | 14 days |
| Refrigerated | 14 days |
| Frozen | 14 days |
| Freeze/thaw cycles | Stable x3 |
Causes for Rejection
Citrate plasma specimen; improper labeling
Test Details
Use
Thyroid function test. Investigation of low thyroxine (T4) result; the differential diagnosis of primary hypothyroidism from normal, and the differential diagnosis of primary hypothyroidism from pituitary/hypothalamic hypothyroidism. TSH is high in primary hypothyroidism. Low TSH occurs in hyperthyroidism. Evaluation of therapy in hypothyroid patients receiving various thyroid hormone preparations: Low values are found in states of excessive thyroid replacement. Normal result on a sensitive TSH assay is acceptable evidence of adequate thyroid replacement.
Follow-up of patients who have had hyperthyroidism treated with radioiodine or surgery. Follow-up low T4 newborn results.
This third-generation TSH assay can be considered a test for thyroid disease. A result within the accepted reference interval provides strong evidence for euthyroidism.
Limitations
Spurious increase from antibovine TSH antibodies by double-antibody technique has been reported.2 TSH may be affected by glucocorticoids, dopamine, and by severe illness,3 and these remain limitations even for the new, sensitive TSH assays. TSH suppression in hypothyroidism with severe illness has been reported with TSH increase with recovery.4 Normal TSH levels in the presence of hypothyroidism have been reported with head injury.5 Iopanoic acid, ipodate, and an antiarrhythmic drug, amiodarone, cause changes in thyroid test results including increases in T4, free T4, and TSH and decreases of T3.6 TSH is not elevated in secondary hypothyroidism.
Probably no single test, even the sensitive immunoassays, can be expected to adequately reflect thyroid status under all circumstances. Among possible problems are the recovery phase of nonthyroidal illness, states of resistance to thyroid hormone, thyrotropin-producing tumors, thyroid status in acute psychiatric illness, early in thyrotoxicosis and in subacute thyroiditis.7
Methodology
Electrochemiluminescence immunoassay (ECLIA)
Reference Interval
See table.1
| Age | Range (μIU/mL) |
|---|---|
| 0 to 6 d | 0.700−15.200 |
| 7 d to 3 m | 0.720−11.000 |
| 3 m 1 d to 12 m | 0.730−8.350 |
| 1 to 5 y | 0.700−5.970 |
| 6 to 10 y | 0.600−4.840 |
| >10 y | 0.450−4.500 |
Additional Information
The consequences of subclinical thyroid disease (serum TSH 0.1−0.45 μIU/mL or 4.5−10.0 μIU/mL) are minimal and current guidelines recommend against routine treatment of patients with TSH levels in these ranges, but thyroid function tests should be repeated at 6- to 12-month intervals to monitor TSH levels;8 however, treatment of subclinical hypothyroidism is indicated in patients with TSH levels >10.0 μIU/mL or in patients with TSH levels <10.0 μIU/mL in conjunction with goiter or positive for antithyroid peroxidase antibodies (or both).9 In patients who are receiving replacement therapy, the dose should be adjusted so serum TSH values range from 0.3−3.0 μIU/mL. An exception is thyroid hormone replacement treatment after thyroidectomy for differentiated thyroid cancer, in which case, a mildly to moderately suppressed TSH level is generally desirable.10 It is reasonable to consider serum TSH measurement for pregnant women or women planning to become pregnant with a family history of thyroid disease, prior thyroid dysfunction, symptoms or physical findings suggestive of hypo- or hyperthyroidism, an abnormal thyroid gland on examination, type 1 diabetes mellitus, or a personal history of autoimmune disorder.11 Suggested upper limit for the TSH reference range for pregnant women and preconception is: first trimester − <2.5 μIU/mL, and 3.0 μIU/mL in the second and third trimesters.10
Unsuspected increase in the level of serum TSH is not uncommon in elderly subjects. A study by Sawin et al found that 22 of 344 (5.9%) healthy persons older than age 60 had a TSH level >10 μIU/mL; 10 of the 22 had low T4 and FT4 index. Elderly hypothyroid individuals may have minimal recognizable clinical symptoms of thyroid deficiency.11 TSH is the single most sensitive test for primary hypothyroidism. If there is clear evidence for hypothyroidism and the TSH is not elevated, hypopituitarism should be considered (secondary hypothyroidism).
TSH levels have been elevated or inappropriately detectable for high thyroid hormone levels in some patients with thyrotropin-secreting pituitary adenomas. Delay in diagnosis of these tumors may lead to visual compromise. The effects of such neoplasms can be misdiagnosed as those of primary hyperthyroidism.
Until the late 1980s, TSH assays were not sufficiently sensitive to distinguish hyperthyroidism from euthyroid (normal) subjects. The new generation of ultrasensitive TSH immunoassays have provided a far more effective diagnostic separation of thyrotoxicosis from euthyroidism.
This assay has a sensitivity of 0.004 μIU/mL and meets all criteria as a third-generation TSH assay.
Thyroxine (T4)
Synonyms
- T4, Total
- Tetraiodothyronine
Special Instructions
This test may exhibit interference when sample is collected from a person who is consuming a supplement with a high dose of biotin (also termed as vitamin B7 or B8, vitamin H, or coenzyme R). It is recommended to ask all patients who may be indicated for this test about biotin supplementation. Patients should be cautioned to stop biotin consumption at least 72 hours prior to the collection of a sample.
Expected Turnaround Time
Within 1 day
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Documents
For more information, please view the literature below.
Thyroid Testing: Assessing Thyroid Disease in Your Patients
Specimen Requirements
Specimen
Serum
Volume
1 mL (adult), 0.8 mL (pediatric)
Minimum Volume
0.5 mL (adult), 0.3 mL (pediatric) (Note: This volume does not allow for repeat testing.)
Container
Red-top tube or gel-barrier tube
Collection
If a red-top tube is used, transfer separated serum to a plastic transport tube.
Storage Instructions
Room temperature
Stability Requirements
| Temperature | Period |
|---|---|
| Room temperature | 14 days |
| Refrigerated | 14 days |
| Frozen | 14 days |
| Freeze/thaw cycles | Stable x3 |
Test Details
Use
Thyroid function test. Decreased in hypothyroidism and in the third stage of (painful) subacute thyroiditis; increased with hyperthyroidism, with subacute thyroiditis in its first stage and with thyrotoxicosis due to Hashimoto disease.3 Used to diagnose T4 toxicosis.
Limitations
T4 may be increased with excess intake of iodine or with surreptitious use of thyroxine.3 T4 levels may be abnormal in the presence of systemic nonthyroidal disease. Alterations in binding capacity or quantity of TBG may increase or decrease total thyroxine without causing symptoms. A common cause of elevated T4 in nonthyroidal disease is said to be liver disease. Serum thyroxine and free thyroxine index (FTI) are increased in familial dysalbuminemic hyperthyroxinemia, a euthyroid syndrome in which an abnormal binding site has affinity for thyroxine.4 The T3 is usually normal in this entity, as is T3 uptake (THBR). Thus, T3 uptake is commonly ordered with T4.
Methodology
Electrochemiluminescence Immunoassay (ECLIA)
Reference Interval
4.5−12.0 μg/dL1,2
Additional Information
The combination of the serum T4 and T3 uptake (THBR) as an indirect assessment of TBG, helps to determine whether an abnormal T4 value is due to alterations in serum thyroxine-binding globulin or to changes of thyroid hormone levels. Deviations of both tests in the same direction usually indicate that an abnormal T4 is due to abnormalities in thyroid hormone. Deviations of the two tests in opposite directions provide evidence that an abnormal T4 may relate to alterations in TBG.
Causes of increased TBG binding include neonatal state, molar and conventional pregnancy, estrogens, oral contraceptives, heroin, methadone, 5-fluorouracil, clofibrate, infectious hepatitis, chronic active hepatitis, and primary biliary cirrhosis, acute intermittent porphyria, lymphoma, and hereditary TBG increase.
Amphetamines, iopanoic acid, ipodate, and amiodarone increase thyroxine.5,6 High dose propranolol may elevate T4 and FTI levels.7
Causes of decreased TBG binding include abnormal protein states especially nephrotic syndrome, androgens, anabolic steroids, prednisone, acromegaly, liver or other systemic illness, severe stress or hereditary TBG deficiency. Salicylates and diphenylhydantoin may lower T4 significantly. Amiodarone may cause increased thyroxine levels and can cause hypothyroidism or hyperthyroidism.
Lithium carbonate may cause goiter with or without hypothyroidism.
Carbamazepine (Tegretol®) is reported to cause decreased values in thyroid function tests.
Thyroxine (T4), Free, Direct
Synonyms
- Free T4, Direct, Serum
- Free Thyroxine
- T4, Free, Direct, Serum
Special Instructions
This test may exhibit interference when sample is collected from a person who is consuming a supplement with a high dose of biotin (also termed as vitamin B7 or B8, vitamin H, or coenzyme R). It is recommended to ask all patients who may be indicated for this test about biotin supplementation. Patients should be cautioned to stop biotin consumption at least 72 hours prior to the collection of a sample.
Expected Turnaround Time
Within 1 day
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Documents
For more information, please view the literature below.
Thyroid Testing: Assessing Thyroid Disease in Your Patients
Specimen Requirements
Specimen
Serum
Volume
0.8 mL
Minimum Volume
0.3 mL (Note: This volume does not allow for repeat testing.)
Container
Red-top tube or gel-barrier tube
Collection
If a red-top tube is used, transfer separated serum to a plastic transport tube.
Storage Instructions
Room temperature
Stability Requirements
| Temperature | Period |
|---|---|
| Room temperature | 14 days |
| Refrigerated | 14 days |
| Frozen | 14 days |
| Freeze/thaw cycles | Stable x3 |
Patient Preparation
Heparin has been reported to have in vivo and in vitro effects on free T4 assay. Hence samples should not be collected during or soon after the administration of this anticoagulant.
Causes for Rejection
Citrate plasma specimen; improper labeling
Test Details
Use
Free T4 may be indicated when binding globulin (TBG) problems are perceived, or when conventional test results seem inconsistent with clinical observations. It is normal in subjects with high thyroxine-binding globulin hormone binding who are euthyroid (ie, free thyroxine should be normal in nonthyroidal diseases). It should be normal in familial dysalbuminemic hyperthyroxinemia.
Limitations
FT4 may be increased with radiologic contrast agents, propranolol, amiodarone, and heparin. It may be decreased with carbamazepine (Tegretol®). Free T4 is a small part of total T4. Increased free T4 levels may occur in subjects with nonthyroid diseases. Such elevations are described as transient.2 Low values were reported in patients with nonthyroidal illness.3 Discrepancies in free T4 levels between methods are recognized.4 Reliability problems continue to be discussed with the direct (analog) methods.5 Results of kits intended to serve in place of equilibrium dialysis technique may differ from the reference method.
Methodology
Electrochemiluminescence immunoassay (ECLIA)
Reference Interval
See table.1
| Age | Range (ng/dL) |
|---|---|
| 0 to 3 d | 0.66−2.71 |
| 4 to 30 d | 0.83−3.09 |
| 31 d to 12 m | 0.48−2.34 |
| 13 m to 5 y | 0.85−1.75 |
| 6 to 10 y | 0.90−1.67 |
| 11 to 19 y | 0.93−1.60 |
| >19 y | 0.82−1.77 |
Tin, Whole Blood
Expected Turnaround Time
3 - 7 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Specimen Requirements
Specimen
Whole blood
Volume
2 mL
Minimum Volume
0.5 mL
Container
Royal blue-top (EDTA) metal-free tube
Storage Instructions
Submission/transport (<3 days): Room temperature. For storage beyond three days, specimen should be refrigerated or frozen.
Causes for Rejection
Use of non−metal-free collection tubes
Test Details
Use
Evaluate exposure to tin
Methodology
Inductively coupled plasma/mass spectrometry (ICP/MS)
Reference Interval
<5.0 ng/mL
Tissue Thromboplastin Inhibition Test (TTIT)
Expected Turnaround Time
3 - 5 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Information
Related Documents
Specimen Requirements
Specimen
Plasma, frozen
Volume
2 mL
Minimum Volume
1 mL
Container
Blue-top (sodium citrate) tube
Collection
Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate.1 Evacuated collection tubes must be filled to completion to ensure a proper blood to anticoagulant ratio.2,3 The sample should be mixed immediately by gentle inversion at least six times to ensure adequate mixing of the anticoagulant with the blood. A discard tube is not required prior to collection of coagulation samples except when using a winged blood collection device (ie, "butterfly"), in which case a discard tube should be used.4,5 When noncitrate tubes are collected for other tests, collect sterile and nonadditive (red-top) tubes prior to citrate (blue-top) tubes. Any tube containing an alternate anticoagulant should be collected after the blue-top tube. Gel-barrier tubes and serum tubes with clot initiators should also be collected after the citrate tubes. Centrifuge and carefully remove the plasma using a plastic transfer pipette, being careful not to disturb the cells. Transfer the plasma into a LabCorp PP transpak frozen purple tube with screw cap (LabCorp N° 49482). Freeze immediately and maintain frozen until tested. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.
Please print and use the Volume Guide for Coagulation Testing to ensure proper draw volume.
Storage Instructions
Freeze. Stable at room temperature for 24 hours.
Patient Preparation
The patient should not be anticoagulated. Do not draw from an arm with a heparin lock or heparinized catheter.
Test Details
Use
Qualitative detection of lupus anticoagulants (LA) in plasma
Limitations
This test was developed, and its performance characteristics determined, by LabCorp. It has not been cleared or approved by the US Food and Drug Administration (FDA).
Methodology
Phospholipid-dependent clotting assay
Reference Interval
0.5−1.2 ratio
TMAO (Trimethylamine N-oxide)
Special Instructions
This assay is not approved for patients of New York State physicians.
Related Documents
For more information, please view the literature below.
TMAO (Trimethylamine N-oxide) Test Technical Review
Specimen Requirements
Specimen
Spun NMR LipoTube (preferred), shipped refrigerated
Volume
1 mL
Minimum Volume
0.5 mL
Container
NMR LipoTube (black-and-yellow-top tube)
Collection
Keep NMR LipoTube (black-and-yellow-top tube) upright at room temperature for 30 minutes and allow to clot. Centrifuge at 1800 to 2200g for 10 to 15 minutes immediately after clotting. If the sample cannot be centrifuged immediately, it must be refrigerated at (2°C to 8°C) and centrifuged within 24 hours of collection. The NMR tube should then be stored at (2°C to 8°C) until shipped. Do not open NMR LipoTube. Serum drawn in gel-barrier collection tubes other than the NMR LipoTube should not be used.
Storage Instructions
Refrigerate
Stability Requirements
| Temperature | Period |
|---|---|
| Room temperature | 14 days |
| Refrigerated | 14 days |
| Frozen | 14 days |
| Freeze/thaw cycles | Stable x3 |
Patient Preparation
TMAO levels are lower in humans who follow a vegetarian or vegan diet than in omnivores.3 Because TMA and TMAO are naturally abundant in some fish,7,8 patients should fast overnight and refrain from consuming fish and other marine food items the day before the blood draw. Fasting for 10 to 12 hours is recommended.
Causes for Rejection
Unspun LipoTube; serum specimen drawn in gel-barrier collection tube other than the NMR LipoTube; sample older than 14 days; plasma samples
Test Details
Use
High levels of TMAO have been associated with an increased risk of heart disease.1
The TMAO test may be used as (1) an aid in the assessment of risk for cardiovascular disease (CVD), independent of established risk factors, (2) an aid in the determination of altered gut microbiome (gut dysbiosis) in individuals who may benefit from intensive dietary intervention, and (3) a monitor therapy aimed at reducing TMAO concentrations.
Limitations
This test was developed and its performance characteristics determined by LabCorp. It has not been cleared or approved by the Food and Drug Administration.
Methodology
Nuclear magnetic resonance (NMR)
Additional Information
TMAO is a dietary metabolite produced by a pathway involving gut microbiota. TMAO concentrations increase in the blood after ingestion of dietary choline and L-carnitine, which are abundant in meat, eggs, liver, and wheat germ and energy drinks. Choline and L-carnitine are metabolized in the gut by microbiota to form trimethylamine (TMA), which is subsequently oxidized in the liver into TMAO by flavin monooxygenases (FMOs). TMAO concentrations have been shown to be reduced in animals and humans treated with broad-spectrum oral antibiotics confirming the requirement for gut bacteria in the formation of TMA and TMAO.2-6 TMAO has been hypothesized to promote atherosclerosis by upregulating macro-phage scavenger receptor activity and downregulating bile acid synthesis which together reduce reverse cholesterol transport.2-6
Tobramycin, Serum, Peak
Synonyms
- AK-Tob™
- Nebcin®
- TOBI®
- Tobrex®
Special Instructions
Expected Turnaround Time
Within 1 day
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Specimen Requirements
Specimen
Serum or plasma
Volume
1 mL
Minimum Volume
0.3 mL
Container
Red-top tube or green-top (heparin) tube. Do not use a gel-barrier tube. The use of gel-barrier tubes is not recommended due to slow absorption of the drug by the gel. Depending on the specimen volume and storage time, the decrease in drug level due to absorption may be clinically significant.
Collection
Transfer separated serum or plasma to a plastic transport tube. Both peak and trough concentrations should be monitored. The trough sample is drawn immediately prior to the next dose. Peak samples should be drawn 60 minutes after an I.M. injection, 30 minutes after the end of a 30-minute I.V. infusion or immediately after a 60-minute I.V. infusion.
Storage Instructions
Room temperature
Stability Requirements
| Temperature | Period |
|---|---|
| Room temperature | 14 days |
| Refrigerated | 14 days |
| Frozen | 14 days |
| Freeze/thaw cycles | Stable x3 |
Causes for Rejection
Gel-barrier tube; severe hemolysis; lipemia; icteric specimen
Test Details
Use
Tobramycin is administered to treat serious infections caused by aerobic gram-negative bacilli (eg, a number of the Enterobacteriaceae, P aeruginosa). These include lower respiratory tract, intra-abdominal, soft tissue, bone or joint, wound, and complicated urinary tract infections; bacteremias; and meningitis.
Tobramycin frequently is the aminoglycoside of choice for infections caused by P aeruginosa because of its greater in vitro activity against this organism; however, superior clinical efficacy is unproven. It usually is given in combination with an antipseudomonal penicillin for severe, systemic P aeruginosa infections.
Some infectious disease experts have preferred the more costly tobramycin to gentamicin for general use in hospitals where resistance is not a problem because it appears to be less nephrotoxic; however, this does not appear to be warranted when all of the available data are evaluated. Amikacin is the aminoglycoside of choice in hospitals where gentamicin and tobramycin resistance is a problem.
Methodology
Immunoassay
Reference Interval
Therapeutic: peak: 6.0−10.0 μg/mL, trough: 0.5−1.5 μg/mL
Critical Value
Potentially toxic: peak: >12.0 μg/mL, trough: >2.0 μg/mL
Additional Information
Tobramycin is cleared by the kidney, and accumulates in renal tubular cells. Nephrotoxicity is most closely related to the length of time that trough levels are >2 μg/mL. Creatinine levels should be monitored every two to three days as this serves as a useful indicator of impending renal toxicity. The initial toxic result is nonoliguric renal failure that is usually reversible if the drug is discontinued. Continued administration of tobramycin may produce oliguric renal failure. Nephrotoxicity may occur in as many as 10% to 25% of patients receiving aminoglycosides; most of this toxicity can be eliminated by monitoring levels and adjusting dosing schedules accordingly. Aminoglycosides may also cause irreversible ototoxicity that manifests itself clinically as hearing loss. Aminoglycoside ototoxicity is relatively uncommon and clinical trials where levels were carefully monitored and dosing adjusted failed to show a correlation between auditory toxicity and plasma aminoglycoside levels. In situations where dosing is not adjusted, however, sustained high levels may be associated with ototoxicity. This association is far from clear cut, and new once-daily dosing regimens (and associated high peak serum concentrations) that fail to enhance toxicity further complicate this issue.
Transferrin
Synonyms
- Siderophilin
Expected Turnaround Time
1 - 2 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Documents
Specimen Requirements
Specimen
Serum (preferred) or plasma
Volume
1 mL
Container
Gel-barrier tube, red-top tube, or green-top (heparin) tube; do not use EDTA plasma.
Storage Instructions
Room temperature
Stability Requirements
| Temperature | Period |
|---|---|
| Room temperature | 14 days |
| Refrigerated | 14 days |
| Frozen | 14 days |
| Freeze/thaw cycles | Stable x3 |
Patient Preparation
Fasting specimen is preferred.
Causes for Rejection
Hemolysis
Test Details
Use
Increased in iron deficiency anemia. It is decreased in chronic inflammatory states, hereditary atransferrinemia, some instances of acquired liver disease, neoplasia, and renal disease. Transferrin is an index of nutritional status.
Limitations
Increased in patients on oral contraceptives and in late pregnancy. May not be elevated in iron-deficient states in which there is severe protein malnutrition (eg, kwashiorkor).
Methodology
Immunologic
Reference Interval
200−370 mg/dL
Additional Information
Transferrin is responsible for 50% to 70% of the iron binding capacity of serum. Since other proteins may bind iron, transferrin is not the same as TIBC. Transferrin is an iron transport protein receiving and binding iron for delivery to receptors at recipient cells. The human transferrin gene, responsible for production of this single chain, 77 kilodalton polypeptide resides on chromosome 3, band q21-25. Transferrin has two iron-binding sites and is largely but not exclusively synthesized by the liver. There are over 20 genetic variants, largely single amino acid substitutions. Transferrin levels rise with iron deficiency and fall in cases of iron overload. Transferrin is normally only about one-third saturated and is responsible for circadian variation in serum iron (peak in AM) due to variable activity of the reticuloendothelial system. Recent studies have indicated that the serum transferrin receptor levels can be used as an index of iron deficiency anemia.
Trazodone
Synonyms
- Desyrel®
- Oleptro™
Expected Turnaround Time
2 - 4 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Documents
Specimen Requirements
Specimen
Serum or plasma
Volume
2 mL
Minimum Volume
0.6 mL
Container
Red-top tube, lavender-top (EDTA) tube, or green-top (heparin) tube. Do not use a gel-barrier tube. The use of gel-barrier tubes is not recommended due to slow absorption of the drug by the gel. Depending on the specimen volume and storage time, the decrease in drug level due to absorption may be clinically significant.
Collection
Transfer separated serum or plasma to a plastic transport tube.
Storage Instructions
Room temperature
Stability Requirements
| Temperature | Period |
|---|---|
| Room temperature | 14 days |
| Refrigerated | 14 days |
| Frozen | 14 days |
| Freeze/thaw cycles | Stable x3 |
Causes for Rejection
Gel-barrier tube
Test Details
Use
Trazodone is a phenylpiperazine propyl derivative of triazolopyridine and is chemically unrelated to tricyclic or tetracyclic antidepressants. It has no monoamine oxidase inhibiting or amphetamine-like properties and little, if any, anticholinergic activity. Its α-adrenergic blocking activity may account for the adverse reactions of dryness of the mouth and hypotension. In therapeutic doses, trazodone inhibits the neuronal uptake of serotonin in man. Trazodone and its metabolite, m-chlorophenylpiperazine, are serotonin agonists as well. Experimentally, prolonged administration decreases the number of serotonin receptors; the uptake of norepinephrine and dopamine is essentially unaffected. After long-term administration, the number of presynaptic α2-adrenergic receptors may be decreased. Controlled studies have demonstrated that trazodone is as effective as amitriptyline and imipramine in patients with major depressive disorders and other subsets of depressive disorders. Because of its sedative effect, trazodone is generally more useful in depressive disorders associated with insomnia and anxiety. This drug does not aggravate psychotic symptoms in patients with schizophrenia or schizoaffective disorders.
Limitations
This test was developed and its performance characteristics determined by LabCorp. It has not been cleared or approved by the Food and Drug Administration.
Methodology
Liquid chromatography/tandem mass spectrometry (LC/MS-MS)
Reference Interval
Therapeutic: 0.8−1.6 μg/mL
Critical Value
Potentially toxic: >5.0 μg/mL
Additional Information
The half-life of trazodone is 4 to 7 hours, peak plasma concentrations with average daily dosing is reached in 2 to 4 hours. When given orally, trazodone is absorbed rapidly, bioavailability is essentially complete, and the mean time to peak absorption is about 1.5 (range 0.5 to 2) hours in fasting and 2.5 hours in nonfasting patients; however, the manufacturer recommends that the drug be taken after a light meal or snack to improve total absorption and diminish the incidence of dizziness and lightheadedness. The volume of distribution is approximately 1 L/kg; protein binding is 96% (at 1 ng/mL).
Trazodone is extensively metabolized by hepatic microsomal enzymes, but enzyme induction has not been observed. Major metabolites include m-chlorophenylpiperazine (active) and triazolopyridine derivative. Two-thirds of the drug and its metabolites are excreted in the urine and one-third appears in the feces. The mean plasma elimination half-life of parent drug is 6 hours. Based on the limited data available at this time, it is not clear whether there is a direct relationship between trazodone plasma levels and its therapeutic effects.
Treponema pallidum (Syphilis) Screening Cascade
Synonyms
- MHA-TP
- Syphilis
- TP-PA
- Trep-Sure™
Test Includes
Reflex to qualitative rapid plasma reagin (RPR) on positives
Expected Turnaround Time
1 - 4 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Documents
For more information, please view the literature below.
Improved Syphilis Reverse Screening Cascade: Earlier Detection With Fewer Ambiguous Results
Specimen Requirements
Specimen
Serum
Volume
1 mL
Minimum Volume
0.5 mL (Note: This volume does not allow for repeat testing.)
Container
Red-top tube or gel-barrier tube
Storage Instructions
Room temperature. Stable at room temperature for seven days, refrigerated for 14 days, or frozen for 14 months.
Causes for Rejection
Hemolysis; lipemia; gross bacterial contamination; plasma specimen
Test Details
Use
Serological test for screening for syphilis infection. This panel includes a Treponema-specific test which may be positive in all stages of syphilis. It may be positive with treponemal infections other than syphilis (bejel, pinta, yaws). Like FTA-ABS and TP-PA, once positive, it remains so; it cannot be used to judge the effectiveness of treatment.
Limitations
The test is not applicable to CSF.
Methodology
Enzyme immunoassay (EIA) with reflex to charcoal flocculation if reactive
Additional Information
The traditional syphilis screening approach when the first-line test is a nontreponemal assay (like RPR) and if positive, the second-line confirmatory test is a treponemal test (such as TP-PA) was developed many years ago when treponemal tests lacked necessary sensitivity but delivered acceptable specificity. In the early 1990s, the CDC published guidelines that recommended the traditional algorithm for screening. Since that time, a number of new, more sensitive treponemal immunoassays have been introduced. In 2008, the CDC issued a report that describes the new syphilis screening approach in which the treponemal test was used as the first-line test, and if positive, reflexes to the nontreponemal test. This report shows that a number of infected individuals would be missed using the traditional approach. In addition, a number of tested individuals would receive false-positive results.1
The implementation of the new approach−if the highly sensitive and specific treponemal assay is used−allows for an improvement in the early detection of syphilis infection that should lead to more effective treatment while preventing the spread of disease. When the treponemal test is positive, it will reflex to qualitative RPR and, if positive, reflex to RPR titer. If the RPR is negative, it will reflex to another (second) treponemal test for confirmation.
Treponema pallidum Antibodies
Synonyms
- MHA-TP
- Syphilis
Expected Turnaround Time
1 - 3 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Documents
For more information, please view the literature below.
Improved Syphilis Reverse Screening Cascade: Earlier Detection With Fewer Ambiguous Results
Specimen Requirements
Specimen
Serum
Volume
1 mL
Minimum Volume
0.5 mL (Note: This volume does not allow for repeat testing.)
Container
Red-top tube or gel-barrier tube
Storage Instructions
Ship specimen at room temperature. Stable at room temperature for seven days, refrigerated for 14 days, or frozen for 14 months.
Causes for Rejection
Hemolysis; lipemia; gross bacterial contamination; plasma specimen
Test Details
Use
Serological test for syphilis. This is a Treponema-specific test and may be positive in all stages of syphilis. It may be positive with treponemal infections other than syphilis (bejel, pinta, yaws). Like FTA-ABS and TP-PA, once positive, it remains so; it cannot be used to judge the effectiveness of treatment. The test is not applicable to CSF.
Methodology
Multiplex flow immunoassay
Trichloroacetic Acid, Urine
Synonyms
- Trichloroethane Metabolite
- Trichloroethylene Metabolite
Expected Turnaround Time
10 - 14 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Specimen Requirements
Specimen
Urine (random)
Volume
10 mL
Minimum Volume
0.5 mL
Container
Plastic urine bottle-no preservative
Collection
End of shift or end of exposure; end of workweek
Storage Instructions
Refrigerate; specimen may also be frozen
Causes for Rejection
Urine from preservative tube
Test Details
Use
Evaluate exposure to trichloroethane, trichloroethylene, or tetrachloroethylene
Methodology
Headspace gas chromatography/electron capture detection (GC/EC); spectrophotometry (SPEC)
Triglycerides
Expected Turnaround Time
Within 1 day
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Information
Related Documents
Specimen Requirements
Specimen
Serum (preferred) or plasma
Volume
1 mL
Minimum Volume
0.5 mL
Container
Red-top tube, gel-barrier tube, green-top (heparin) tube, or lavender-top (EDTA) tube. Do not use glycerinated Vacutainer® tubes.
Collection
Separate serum or plasma from cells within 45 minutes of collection.
Storage Instructions
Maintain specimen at room temperature.
Stability Requirements
| Temperature | Period |
|---|---|
| Room temperature | 7 days |
| Refrigerated | 14 days |
| Frozen | 14 days |
| Freeze/thaw cycles | Stable x3 |
Patient Preparation
Patient should be fasting 12 to 14 hours. The patient should be on a stable diet two weeks prior to collection of blood.
Causes for Rejection
Specimen collected in a glycerinated tube; improper labeling
Test Details
Use
Evaluate turbid samples of blood, plasma, and serum; work up of chylomicronemia; evaluate hyperlipidemia; occasional cases of diabetes mellitus and/or pancreatitis are detected by hypertriglyceridemia. High levels may occur with hypothyroidism, nephrotic syndromes, carbohydrate-sensitive hypertriglyceridemia, glycogen storage disease, and in hyperlipoproteinemias type I, IIb, III, IV, and V. Some alcoholics have hypertriglyceridemia which disappears with abstinence. Extremely high triglyceride levels may occur with alcohol abuse. Triglyceride is needed for calculation of LDL-C (low-density lipoprotein cholesterol) concentration. Disturbances in triglyceride metabolism relate to diabetes and are a risk factor for atherosclerotic disease, but not an independent one.1
Although the role of hypertriglyceridemia as a risk factor for coronary arterial disease has been controversial, a more consistent association for women exists and analysis of preliminary data supports triglyceride levels as a predictor in men with lower LDL cholesterol levels2 and with cholesterol values <220 mg/dL.3
In familial combined hyperlipidemia, hypertriglyceridemia may be found before hypercholesterolemia. Nevertheless, a strong case is not available for primary triglyceride evaluation of healthy persons without positive family history of coronary disease or other risk factors. Some knowledgeable authorities favor testing with lipid panels, including triglycerides, for reasons discussed elsewhere in this listing.
In exogenous hypertriglyceridemia, chylomicrons float as a layer in the tube of refrigerated, stored serum.
Limitations
If triglyceride is >400 mg/dL, LDL cannot be calculated accurately by the Friedewald formula.4 Some women on estrogens and high estrogen oral contraceptives have an increase of triglyceride. Increases occur with pregnancy, similar to those with oral contraceptives. The most common cause of triglyceride increase is inadequate patient fasting. Hypertriglyceridemia is associated with use of thiazide diuretics and β-adrenergic blocking agents.
Methodology
Enzymatic
Reference Interval
• Normal: <150 mg/dL
• Borderline-high: 150−199 mg/dL
• High: 200−499 mg/dL
• Very high: >500 mg/dL
Additional Information
Triglycerides commonly increase with obesity and may increase with chronic renal or liver disease. A positive association exists between diabetes mellitus and hypertriglyceridemia. Extremely high triglyceride levels suggest the possibility of pancreatitis. Chylomicronemia, although associated with pancreatitis, is not accompanied by increased atherogenesis. Chylomicrons are not seen in normal fasting serum, but are found in the sera of normal subjects following a fatty meal as exogenous triglycerides. Left refrigerated, chylomicrons float to the surface of a sample overnight; VLDL remain in suspension. Triglyceride physiologically is carried mostly as very low-density lipoproteins (VLDL). The triglyceride in VLDL is endogenous from hepatic synthesis.
When turbidity of blood, serum, or plasma is seen, triglyceride is often >350 mg/dL. Fasting chylomicronemia occurs with but is not limited to deficiency of apo-CII (apolipoprotein work-up). It occurs also with deficiency of lipoprotein lipase, an enzyme.
A positive association exists between gout and hypertriglyceridemia.
Drug effects have been summarized.5
Triiodothyronine (T3)
Synonyms
- T3, Total
Special Instructions
This test may exhibit interference when sample is collected from a person who is consuming a supplement with a high dose of biotin (also termed as vitamin B7 or B8, vitamin H, or coenzyme R). It is recommended to ask all patients who may be indicated for this test about biotin supplementation. Patients should be cautioned to stop biotin consumption at least 72 hours prior to the collection of a sample.
Expected Turnaround Time
Within 1 day
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Information
Related Documents
For more information, please view the literature below.
Thyroid Testing: Assessing Thyroid Disease in Your Patients
Specimen Requirements
Specimen
Serum
Volume
0.8 mL
Minimum Volume
0.3 mL (Note: This volume does not allow for repeat testing.)
Container
Red-top tube or gel-barrier tube
Collection
If a red-top tube is used, transfer separated serum to a plastic transport tube.
Storage Instructions
Room temperature
Stability Requirements
| Temperature | Period |
|---|---|
| Room temperature | 14 days |
| Refrigerated | 14 days |
| Frozen | 14 days |
| Freeze/thaw cycles | Stable x3 |
Causes for Rejection
Citrate plasma specimen; improper labeling
Test Details
Use
Thyroid function which is particularly useful in the diagnosis of T3 thyrotoxicosis, in which T3 is increased and T4 is within normal limits. T3 toxicosis is occasionally found in Graves' disease. It occurs with a single toxic nodule, multinodular thyrotoxicosis, and following treatment with T3 (Cytomel®).2 It is increased in and occasionally helpful for confirmation of diagnosis of conventional hyperthyroidism, in which commonly both T3 and T4 levels are increased. T3 is needed in patients with clinical evidence for hyperthyroidism, in whom the usual thyroid profile is normal or borderline.
Reported to be normal to slightly increased with familial dysalbuminemic hyperthyroxinemia.
Recommended for patients with supraventricular tachycardia, for patients with fatigue and weight loss not otherwise explained, or for those with proximal myopathy and in whom T4 levels are not elevated.3
Limitations
T3 is decreased with nonthyroidal chronic diseases and influenced by the state of nutrition. It is not helpful for evaluation of hypothyroidism. It may be normal with thyrotoxicosis (thyroxine thyrotoxicosis).4
Variations in TBG and other binding proteins can affect T3. Such increases may be found with use of oral contraceptives, pregnancy, and other binding protein abnormalities. Fasting causes T3 and TSH to decrease.5
Methodology
Electrochemiluminescence immunoassay (ECLIA)
Reference Interval
See table.1
| Age | Range (ng/dL) |
|---|---|
| 0 to 3 d | 96−292 |
| 4 to 30 d | 62−243 |
| 31 d to 12 m | 81−281 |
| 13 m to 5 y | 83−252 |
| 6 to 10 y | 92−219 |
| >10 y | 71−180 |
Additional Information
Increased T3 often occurs in hyperthyroidism, but in approximately 5% of cases only T3 is elevated, “T3 toxicosis.” Do not confuse T3 with T3 uptake; these are two different tests. The latter is done very commonly as part of the usual thyroid profile. Less than 1% of T3 is unbound.
Triiodothyronine (T3), Free
Synonyms
- Free T3
- T3, Free
Special Instructions
This test may exhibit interference when sample is collected from a person who is consuming a supplement with a high dose of biotin (also termed as vitamin B7 or B8, vitamin H, or coenzyme R). It is recommended to ask all patients who may be indicated for this test about biotin supplementation. Patients should be cautioned to stop biotin consumption at least 72 hours prior to the collection of a sample.
Expected Turnaround Time
1 - 2 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Information
Related Documents
For more information, please view the literature below.
Thyroid Testing: Assessing Thyroid Disease in Your Patients
Specimen Requirements
Specimen
Serum
Volume
0.8 mL
Minimum Volume
0.3 mL (Note: This volume does not allow for repeat testing.)
Container
Red-top tube or gel-barrier tube
Collection
If a red-top tube is used, transfer separated serum to a plastic transport tube.
Storage Instructions
Room temperature
Stability Requirements
| Temperature | Period |
|---|---|
| Room temperature | 14 days |
| Refrigerated | 14 days |
| Frozen | 14 days |
| Freeze/thaw cycles | Stable x3 |
Causes for Rejection
Citrate plasma specimen; improper labeling
Test Details
Use
Evaluate thyroid function and assess abnormal binding protein disorders
Limitations
Circulating antibodies to thyroid hormones have also been reported to interfere with free hormone immunoassays.
Methodology
Electrochemiluminescence immunoassay (ECLIA)
Reference Interval
See table.1
| Age | Range (pg/mL) |
|---|---|
| 0 to 3 d | 2.0−7.9 |
| 4 to 30 d | 2.0−5.2 |
| 31 d to 12 m | 1.6−6.4 |
| 13 m to 5 y | 2.0−6.0 |
| 6 to 10 y | 2.7−5.2 |
| 11 to 19 y | 2.3−5.0 |
| >19 y | 2.0−4.4 |
Additional Information
Triiodothyronine (T3) normally represents only approximately 5% of the thyroid hormone and like thyroxine is almost entirely bound to the carrier proteins, with only 0.25% of the total being in the free state. Measurement of free triiodothyronine is of value in confirming the diagnosis of hyperthyroidism, when an elevated free or total thyroxine level is found. Abnormal total and free triiodothyronine concentrations may appear in T3 toxicosis, in the presence of normal thyroxine levels. Free T3 levels are unaffected by carrier protein variation.
Trimellitic Anhydride
Expected Turnaround Time
3 - 4 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Information
Related Documents
Specimen Requirements
Specimen
Serum
Volume
0.2 mL
Container
Red-top tube or gel-barrier tube
Storage Instructions
Room temperature
Stability Requirements
| Temperature | Period |
|---|---|
| Room temperature | 14 days |
| Refrigerated | 14 days |
| Frozen | 3 months |
| Freeze/thaw cycles | Stable x3 |
Test Details
Methodology
Thermo Fisher ImmunoCAP®
Trypsin
Synonyms
- Trypsinogen (Cathodic)
Expected Turnaround Time
4 - 9 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Documents
Specimen Requirements
Specimen
Serum, frozen
Volume
1 mL
Minimum Volume
0.5 mL (Note: This volume does not allow for repeat testing.)
Container
Red-top tube or gel-barrier tube
Collection
Transfer serum into a LabCorp PP transpak frozen purple tube with screw cap (LabCorp N° 49482). Freeze immediately and maintain frozen until tested. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.
Storage Instructions
Freeze.
Patient Preparation
No radioisotopes administered 24 hours prior to venipuncture
Causes for Rejection
Recently administered radioisotopes; specimen not received frozen; plasma specimen received
Test Details
Use
Trypsin is considered to be a specific indicator of pancreatic damage. This assay is useful in the evaluation of acute pancreatitis. Trypsin levels reach a maximum volume of five- to tenfold the upper normal limit and remain elevated for four to five days after the onset of abdominal pain. Trypsin determination may also be of value in evaluating patients with cystic fibrosis and pancreatic carcinoma.
Limitations
There is no internationally accepted calibrator for trypsin at present. The trypsin RIA values cannot be readily compared with the results of other trypsin assays.
Methodology
Radioimmunoassay (RIA)
Reference Interval
169−773 ng/mL
Tryptase
Synonyms
- Mast Cell Tryptase
Expected Turnaround Time
2 - 4 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Information
Related Documents
Specimen Requirements
Specimen
Serum or plasma
Volume
0.7 mL
Minimum Volume
0.5 mL (Note: This volume does not allow for repeat testing.)
Container
Gel-barrier tube, lavender-top (EDTA) tube, or green-top (heparin) tube
Collection
Separate serum or plasma from cells and transfer to a plastic transport tube.
Storage Instructions
Refrigerate
Stability Requirements
| Temperature | Period |
|---|---|
| Room temperature | 7 days |
| Refrigerated | 14 days |
| Frozen | 14 days |
| Freeze/thaw cycles | Stable x3 |
Causes for Rejection
Gross hemolysis; lipemic samples
Test Details
Use
This test measures total tryptase (alpha and beta tryptase). Tryptase is the most abundant protein component of human mast cell secretory granules.1,2 Serum levels generally reflect the extent of mast cell activation either by IgE- or non-IgE-mediated mechanisms. Basophils also produce small amounts of tryptase.
Methodology
ImmunoCAP®
Reference Interval
2.2−13.2 μg/L
Additional Information
Tryptase is often ordered as part of the diagnostic assessment of a patient suspected of having mastocytosis (either cutaneous or systemic).3-5 Serum levels are thought to correlate with mast cell "burden" in these patients.5 Mastocytosis is considered in the differential diagnosis of patients that experience severe allergic reactions without any identifiable specific trigger. Systemic mastocytosis can produce symptoms suggestive of organ involvement, such as peptic ulcers, chronic diarrhea, and joint pain. These patients may display evidence of enlargement of the liver, spleen, or lymph nodes. There may be skin involvement with rashes or characteristic red blistering lesions.
Tryptase may be ordered to help confirm anaphylaxis as the cause of an individual's acute symptoms, especially when the diagnosis is not clear and/or the symptoms are recurrent.6,7 With anaphylaxis, tryptase levels typically peak about one to two hours after symptoms begin and then decline slowly within the next three to six hours. The biological half-life for tryptase is about two hours.
Systemic mastocytosis is a risk factor for anaphylactic reactions, particularly in response to drugs8,9 and insect stings.10-15 Patients with elevated baseline tryptase levels may be at increased risk for severe anaphylactic reactions. The risk associated with baseline elevated tryptase levels is greater in individuals with a known history of severe systemic reactions. Transiently increased tryptase levels measured during severe reaction to an allergen, such as insect venom or an anesthetic drug, suggest that mast cell activation may have had a role in causing the reaction.
Pathological increased levels of tryptase reflect the mast cell burden in certain hematological abnormalities and neoplasms, irrespective if systemic mastocytosis is established or not.16 Hematological disorders that involve uncontrolled growth of immature myeloid cells in the bone marrow and/or the circulation can produce increased serum tryptase levels. Several therapeutic drugs have been developed for cytoreductive therapy of systemic mastocytosis and hematological neoplasms.17 During treatment tryptase measurements is a useful monitoring and prognostic tool.
Common Lab Tests
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This test, also known as a CBC, is the most common blood test performed. It measures the types and numbers of cells in the blood, including red and white blood cells and platelets. This test is used to determine general health status, screen for disorders and evaluate nutritional status. It can help evaluate symptoms such as weakness, fatigue and bruising, and can help diagnose conditions such as anemia, leukemia, malaria and infection.
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Also known as PT and Pro Time, this test measures how long it takes blood to clot. This coagulation test measures the presence and activity of five different blood clotting factors. This test can screen for bleeding abnormalities, and may also be used to monitor medication treatments that prevent the formation of blood clots.
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This test measures glucose, sodium, potassium, calcium, chloride, carbon dioxide, blood urea nitrogen and creatinine which can help determine blood sugar level, electrolyte and fluid balance as well as kidney function. The Basic Metabolic Panel can help your doctor monitor the effects of medications you are taking, such as high blood pressure medicines, can help diagnose certain conditions, or can be part of a routine health screening. You may need to fast for up to 12 hours before this test.
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The lipid panel is a group of tests used to evaluate cardiac risk. It includes cholesterol and triglyceride levels.
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The liver panel is a combination of tests used to assess liver function and establish the possible presence of liver tumors.
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This test is used to diagnose and monitor diabetes.
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Often the first lab test performed, this is a general screening test used to check for early signs of disease. It may also be used to monitor diabetes or kidney disease.
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Cultures are used to test for diagnosis and treatment of infections. Illnesses such as urinary tract infections, pneumonia, strep throat, MRSA and meningitis can be detected and tested for appropriate antibiotic treatment.
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