*6.2.2. TFPI*

TFPI is a single chain polypeptide with specialized domains called Kuntz domains. It is primarily synthesized in endothelial cells, liver and macrophages [7]. TFPI is mainly bound to the endothelial cell surface through glycosaminoglycans. TFPI circulates in the plasma at a concentration of 1.0–2.5 nM with a half-life of 60–120 min. Major portion of plasma TFPI is bound to LDL and levels of TFPI are regulated by thyroid hormones. TFPI is cleared from the system by liver and kidney. TFPI directly binds to FVIIa, FXa complex and inhibits their function. Inhibitory function of TFPI is enhanced in presence of Protein S [7]. Low levels of TFPI increases the risk of thrombosis by 2 fold [119].
