Free thyroxine FT4 Test Kits Reagent Kits Diagnostic Lab Reagents for POCT/CLIA Analyzer

Four iodine thyronine (Tetraiodothyronine, T4) is thyroid hormone  by the synthesis and secretion of thyroid follicular cells; with a  molecular weight of 777, half-life of 6-7 days. It is synthesized by  the tyrosine residues of thyroglobulin iodination, and then come  into the blood circulation by enzymatic hydrolysis which plays an  important role in the body's metabolism and growth. 

Formation and release of T4 is regulated by the thyroid stimulating  hormone (TSH). Most of the T4 (99%) in vivo is binding with the  transport protein, which includes thyroid-binding protein (TBG),  prealbumin (TBPA) and albumin. Only a very small amount of T4  (about 0.04%) is free in serum. TBG concentration regulates the  concentration of T4, but the concentration of FT4 is not affected.  Binding T4 and free T4 was reversible equilibrium. And only FT4 can enter the target cells and binds with the receptor to exert its  physiological functions. T4 affects metabolism of proteins, lipids  and carbohydrates in vivo and in peripheral tissues it can be  further 5 'deiodinated into a more active thyroid hormone (T3).