|Products||Total T3 RIA Test|
|Company||Diagnostic Systems Laboratories, Inc.|
|Item||Total T3 RIA Test|
|Description|| Triiodothyronine (T3) is produced primarily by 5-monodeioination of thyroxine (T4) in extrathyroidal tissues. Within the thyroid gland, T3 production occurs at a rate which is ~3-fold lower than that for T4. Release of T3 from the thyroid gland into the blood is ~5-8 micrograms/day as compared to 80-100 micrograms/day for T4. In addition, approximately 22 mg/day of T3 is produced by nonthyroidal 5-monodeionination of T4 . In the circulation, T3 is bound to thyroxine-binding globulin (although with less affinity than T4), and also to albumin [1,2]. Although the circulating levels of total and free T3 are several fold lower than for total and free T4, thyroid hormone receptor affinity is much higher for T3. Therefore, T3 has a much faster turnover (T ~1 day, compared to ~6 days for T4) and has greater biological potency than T4. Measurement of total serum T3 concentrations is a standard and well-validated test of thyroid gland function .
|Info|| Diagnostic Systems Laboratories, Inc.|
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