Hageman factor deficiency presentation and implications for management.

One of the more fascinating aspects of patient management arises when dealing with coagulation disorders. Factor XII deficiency, first described by Ratnoff in 1968, is one such coagulation disorder which provides some interesting challenges in management. Factor XII deficiency has been shown to be an inherited autosomal recessive disorder. The presence of Hageman factor abnormality trait can be clinically suspected in a patient with a prolonged activated partial thromboplastin time (APTT), normal prothrombin time (PT), normal bleeding time, and no clinical history of bleeding. Once suspected, the deficiency can be confirmed by normalization of partial thromboplastin time (PTT) with normal aged plasma and by factor assay. The importance of understanding the mechanism of factor XII deficiency has clinical significance when attempts are made to heparinize individuals who have this deficiency. Three methods can be used to monitor therapy: the chromogenic heparin assay, the citrated thrombin time, and the recalcified thrombin time. Two cases are presented.