tailieunhanh - Chapter 101. Hemolytic Anemias and Anemia Due to Acute Blood Loss (Part 1)

Harrison's Internal Medicine Chapter 101. Hemolytic Anemias and Anemia Due to Acute Blood Loss Definitions A finite life span is a distinct characteristic of red cells. Hence, a logical, time-honored classification of anemias comprises three groups: decreased production of red cells, increased destruction of red cells, and acute blood loss. Red cell destruction and acute loss, both associated with increased reticulocyte production, are covered in this chapter. Red cell production defects are discussed in Chaps. 98, 99, and 100. Physical loss of red cells from the bloodstream—which in most cases also means physical loss from the body—is fundamentally different from. | Chapter 101. Hemolytic Anemias and Anemia Due to Acute Blood Loss Part 1 Harrison s Internal Medicine Chapter 101. Hemolytic Anemias and Anemia Due to Acute Blood Loss Definitions A finite life span is a distinct characteristic of red cells. Hence a logical time-honored classification of anemias comprises three groups decreased production of red cells increased destruction of red cells and acute blood loss. Red cell destruction and acute loss both associated with increased reticulocyte production are covered in this chapter. Red cell production defects are discussed in Chaps. 98 99 and 100. Physical loss of red cells from the bloodstream which in most cases also means physical loss from the body is fundamentally different from destruction of red cells within the body. Therefore the clinical aspects and the pathophysiology of anemia in these two groups of patients are quite different and they will be considered separately. Hemolytic Anemias Anemias due to increased destruction of red cells or hemolytic anemias HAs may be inherited or acquired. From the clinical point of view they may be more acute or more chronic and they may vary from mild to very severe. The site of hemolysis may be predominantly intravascular or extravascular. With respect to mechanisms HAs may be due to intracorpuscular or extracorpuscular causes Table 101-1 however before reviewing the individual types of HAs it is appropriate to consider what they have in common. Table 101-1 Classification of Hemolytic Anemias Intracorpuscular Defects Extracorpuscular Factors Hereditary Hemoglobinopathies Familial hemolytic uremic syndrome HUS Enzymopathies Membrane-cytoskeletal defects Acquired Paroxysmal nocturnal hemoglobinuria PNH Mechanical destruction microangiopathic Toxic agents Drugs Infectious Autoimmune There is a strong correlation between hereditary causes and intracorpuscular defects because such defects are due to inherited mutations the one exception is PNH because the defect is due to an .