Prekallikrein deficiency in a 15-year-old boy with Ménière's disease: a case report.

Congenital prekallikrein deficiency is a rare disorder in which there is an in vitro clotting defect despite absence of bleeding or thrombotic tendency. In this report, a 15-year-old boy with an unexpected markedly prolonged activated partial thrombin time, a normal prothrombin time, and without personal nor familial history of bleeding or thrombosis is presented. Laboratory investigation revealed a severe prekallikrein deficiency. This case highlights the importance of following a diagnostic algorithm to establish the correct diagnosis. Moreover, by selecting appropriate laboratory tests, unnecessary and repeatedly testing can be avoided.