T3

DESCRIPTION:
T3 is metabolically more active than thyroxine. Its half-life is 1 day, and in plasma, it is bound to specific proteins that bind thyroid hormones. T3 concentrations become abnormal earlier than T4 concentrations and normalize later than T4. This test measures the concentration of triiodothyronine in the blood. T3 is one of the two main hormones produced by the thyroid gland (the other hormone is thyroxine T4). T3 accounts for less than 10% of thyroid hormones, while T4 makes up the rest; however, T3’s action is approximately 4 times stronger than T4’s. Many cells in your body can convert T4 to T3; T4 is the main “reservoir” used to create T3. Approximately 99.7% of T3 is protein-bound, and the remainder is free (about 0.3%). The concentration of bound and unbound T3 or free T3 (fT3) can be determined in the blood.

DETERMINATION:
Method of determination: ECLIA. The sample for analysis is serum or plasma (EDTA or heparin). The sample is stable for 7 days at 2-8°C, and 30 days at -20°C.

RESULT:
The reference interval depends on gender, age, and the determination method. The reference interval is displayed on each validated report.