Hereditary hemorrhagic telangiectasia (HHT) also known as Osler-Weber-Rendu (OWR) disease is an inherited disorder that leads to the development of mucocutaneous telangiectasia and visceral organ arteriovenous malformations (AVMs). HHT is the result of mutations in key regulators of angiogenesis, which…
Confined to the vascular system, blood comes into contact only with endothelial cells, which line all macrovascular, microvascular, and sinusoidal systems. Disruption of this closed system leads to bleeding—either gross bleeding (characteristic of macrovascular hemorrhage) or extravasation into tissue or…
Introduction Platelet dysfunction and thrombocytopenia result from a variety of inherited and acquired disorders. When a patient with mucocutaneous bleeding is first evaluated, the list of differential diagnoses is usually extensive. Elements of the medical history, the physical examination, and…
Immune thrombocytopenia (ITP), formerly called idiopathic thrombocytopenic purpura, is a common acquired bleeding disordered characterized by isolated thrombocytopenia in the absence of a clinically apparent cause. Currently there is no diagnostic test for ITP; thus establishing the diagnosis can be…
Introduction Of the circulating blood cells, the platelet was the last to be fully described and its attributes determined. Although early studies by Osler, Hayam, and Bizzozero had identified small particles in the blood, these were thought to be bacteria,…
von Willebrand disease (VWD), transmitted in an autosomal fashion, is the most common of the inherited bleeding disorders. It is caused by a decrease in the quantity of von Willebrand factor (VWF) or a qualitatively abnormal VWF in the circulation…
Introduction and Overview In 1941 Lawrence and Johnson described a “circulating anticoagulant” in a patient with hemophilia who became refractory to blood transfusions for the treatment of bleeding. Over the next several years, they and others determined that this substance…
In this chapter the less common congenital disorders of hemostasis are discussed. These include disorders of fibrinogen, prothrombin, and factors V, VII, X, and XI. (Disorders of factors VIII and IX are discussed in Chapter 3 .) In addition, the…
Epidemiology and Genetics The hemophilias are the best known of the hereditary bleeding disorders. Hemophilia A or B arises as the result of a congenital deficiency of coagulation factor protein VIII or IX, respectively. Both are X-linked recessive disorders, almost…
Introduction In the current medical climate of laboratory expertise and automation, an expanded menu of increasingly sophisticated testing can provide immediately meaningful diagnostic, therapeutic, and prognostic indicators. On the other hand, economic justification and insurance “gatekeeping” often constrain the physician's…