Thrombocytopenia is defined as a platelet count below the lower limit of the normal range (≈150 × 10 9 /L). Sometimes, an expanded definition of thrombocytopenia is appropriate. For example, an abrupt drop in the platelet count can signify the…
Platelets are anucleate cells that are required for primary hemostasis. A normal platelet count is 150,000 to 400,000 platelets per microliter of blood, with a normal lifespan of 7 to 10 days for circulating platelets. The body clears 10 11…
Acquired disorders of platelet function are among the most common hematologic abnormalities, which reflects the sensitivity of platelets to external and internal perturbations. The clinical challenge in evaluating acquired disorders of platelet function is to determine whether observed derangements in…
This chapter provides a practical approach to the laboratory evaluation of hemostatic and thrombotic disorders. Any assessment of hemostatic or thrombotic disorders must start with a thorough history and physical examination. These can provide clues to guide subsequent laboratory testing,…
Bruising and bleeding are common reasons for a hematology referral. Some consults are for management of an acute bleed in someone who may have a hemorrhagic disorder. Such bleeds may be spontaneous or occur after surgery or trauma, and the…
Blood is the principal vehicle delivering oxygen and nutrients to the various tissues and organs of the body. Blood flow and the integrity of the vasculature are essential to life itself. The hemostatic process has evolved to provide damage recognition…
A primary physiological role of platelets is to support hemostasis at sites of vascular injury by forming a plug that arrests blood loss ( Fig. 124.1 ). Normally, disc-shaped platelets circulate in the bloodstream without adhering to the endothelium of…
Platelets are small anucleate fragments that are formed from the cytoplasm of megakaryocytes and have a characteristic discoid shape. To assemble and release platelets, megakaryocytes become polyploid by endomitosis and follow a maturation program that results in the conversion of…
Hemostatic, Hematopoietic, and Vascular Systems as a Functional Continuum Diseases affecting the bone marrow (BM) and peripheral blood are closely intertwined with the state of the vascular system, which acts as a niche, conduit, and regulator of blood cells. This…
Introduction Hemostasis preserves vascular integrity by balancing the physiologic processes that maintain blood in a fluid state under normal circumstances and prevent excessive bleeding after vascular injury. Preservation of blood fluidity depends on an intact vascular endothelium, and a complex…