Test Code 1014
Test Details
Total T3 (Triiodothyronine or T3)
Total T3 (triiodothyronine) is a hormone generated by converting T4 to T3 in the body’s tissue. T3 is the active thyroid hormone and is necessary for normal body metabolism.
Methodology
Chemiluminescence immunoassay
Patient Preparation
None
Preferred Specimen
1.0 mL serum collected in a serum separator tube (SST / Tiger Top)
Alternate Specimen
None
Transport Temperature
Refrigerated (ship on frozen cold packs)
Stability
Refrigerated: 14 days
Lab Values
Total T3 (Triiodothyronine or T3)
- Low: <0.8 ng/mL
- Optimal: 0.8-2.0 ng/mL
- High: >2.0 ng/mL
Clinical Significance
Total T3 (Triiodothyronine or T3)
- Low Total T3 levels are consistent with hypothyroidism or inadequate thyroid hormone replacement.1-3
- High Total T3 levels are consistent with either hyperthyroidism or excess thyroid hormone replacement.1-3
- These assays no longer show biotin interference in serum concentrations up to 1200 ng/mL.
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
Total T3 (Triiodothyronine or T3)
Treatment is based on cause of Total T3 elevation/reduction.
