A study of fibrinogen turnover in classical hemophilia and congenital afibrinogenemia.

I T HAS BEEN postulated that in the normal individual a continuous clotting process occurs which utilizes fibrinogen to maintain normal vascular integrity.’4 This thesis has been used to account for the shorter half-life of fibrinogen as compared to other plasma proteins.54 According to this theory, individuals with severe impairment of clotting not attributable to abnorinalities involving fibrinogen should not utilize available fibrinogen as readily as the normal person. The turnover of circulating fibrinogen in such a patient \VOul(l he slower than in the normal person. If, however, fibrinogen turnover is not (lue primarily to its utilization in clotting, then such individuals should have normal fibrincgen turnover rates. In order to evaluate the role of clotting in the turnover of fibrinogen, the metabolism of Il:ml laheled fibrinogen was determined in six patients with classical hemophilia of varying severity. A concurrent turnover study was performed in a boy with congenital afibrinogenemia. The data indicate that at least the major part of the turnover of fibrillogen is probably not attributable to in vivo clotting.