Hemophilia A, Hemophilia B, congenital von willebrand disease, and acquired von willebrand syndrome

Hemophilia A, hemophilia B, and von Willebrand disease can present as bleeding diathesis with an isolated prolonged activated partial thromboplastin time. These conditions are sometimes difficult to differentiate and can occur concurrently, further complicating diagnosis and management. This chapter will discuss hemophilia A and hemophilia B in terms of diagnostic criteria and factor VIII and factor IX physiology. In addition, this chapter will also review both quantitative and qualitative von Willebrand disease. Quantitative von Willebrand disease includes Type 1 and 3 disorders. On the other hand, qualitative disease implies functional defects either in coagulation function (Type 2A, 2B, and 2M disease) or in factor VIII carrier function (Type 2N disease). Pseudo-von Willebrand disease, as its name suggests, is not a true von Willebrand disease, but a platelet glycoprotein Ib receptor gain-of-function disorder which results in laboratory findings that mimic Type 2B disease. Acquired von Willebrand syndrome represents a collection of von Willebrand factor abnormalities that have been associated with a number of known diseases such as aortic valve stenosis and hypothyroidism. The laboratory findings of acquired von Willebrand syndrome often resemble congenital von Willebrand disease subtypes.