Test Code 1005
Test Details
Thyroid Stimulating Hormone (TSH)
TSH is a peptide hormone synthesized and secreted by the anterior pituitary gland. TSH regulates thyroid gland function.
Methodology
Immunoassay
Patient Preparation
None
Preferred Specimen
1.0 mL serum (0.5 mL minimum) collected in serum separator tube (SST/Tiger Top)
Alternate Specimen
Dried Blood collected on an AdvanceDx 100 card
Transport Temperature
Refrigerated (ship on frozen cold packs)
Stability
Refrigerated: 14 days
Lab Values
Thyroid Stimulating Hormone (TSH)
- Low: <0.27 µlU/mL
- Optimal: 0.27-4.20 µlU/mL
- High: >4.20 µlU/mL
Clinical Significance
Thyroid Stimulating Hormone (TSH)
- TSH is used in the differential diagnosis of primary, secondary, & tertiary hypothyroidism.1-3
- Is also useful in screening for hyperthyroidism.1-3
- Allows adjustment of thyroid replacement in hypothyroid patients.1-3
- High doses of biotin (> 5 mg/day) may interfere with assay results. Patient assumed to be refraining from biotin supplementation for at least 3 days prior to blood draw.
References:
- Goodman N, Cobin RH. Reproductive disorders. In: Camacho PM, Gharib H, Sizemore GW, eds. Evidence-Based Endocrinology. 3rd ed. Philadelphia, PA: Lippincott Williams & Wilkins. 2012:190-228.
- Castro MR, Gharib H. Thyroid disorders. In: Camacho PM, Gharib H, Sizemore GW, eds. Evidence-Based Endocrinology. 3rd ed. Philadelphia, PA: Lippincott Williams & Wilkins. 2012:43-80.
- Garber JR, Cobin RH, Gharib H, et al. Clinical practice guidelines for hypothyroidism in adults: cosponsored by the American Association of Clinical Endocrinologists and the American Thyroid Association. Endocr Pract. 2012;18(6):988-1028.
Treatment Options
Thyroid Stimulating Hormone (TSH)
- Low value is consistent with either an overactive thyroid gland or excess thyroid hormone replacement. Additional diagnostic testing such as Free T4 and/or Total T3 as required.
- High value is consistent with an underactive thyroid gland or inadequate thyroid hormone replacement. Additional diagnostic testing such as Free T4 and/or Total T3 as required.
