Adult-onset Vitamin K-dependent Coagulation Factor Deficiency of Unidentified Etiology.

Symptoms of bleeding caused by vitamin K-dependent coagulation factor deficiency (VKCFD) are rare in adults. We present two Japanese cases of adult-onset VKCFD, in which the cause of vitamin K deficiency remains unknown despite comprehensive evaluation. Both patients showed markedly decreased levels of coagulation factors (F) VII, FIX, FX, FII, protein C, and protein S, along with elevated levels of protein induced by vitamin K absence/antagonist II. The clinical course in both cases ruled out congenital VKCFD. Based on these findings and a similar case in the relevant literature, we propose a new disease entity, idiopathic acquired VKCFD.