The hemolytic anemias are classified according to many different schemes. In this chapter, we have classified the hemolytic anemias according to the site of hemoly-sis by classifying hemolytic events as either extravascu-lar or intravascular. Yet many textbooks discuss the
Table 4.3 O Hemolytic Anemias Classified by Intrinsic or Extrinsic Defects (Modified List)
Intrinsic Red Cell Defects Leading to Hemolysis
Extrinsic Defects Leading to Hemolysis
Hemoglobinopathies: structural and synthetic
Red cell membrane defects
Red cell enzyme defects
Stem cell defects
Autoimmune hemolytic anemia
Environmental agents, including venoms and chemical agents hemolytic anemias in terms of those that result from intrinsic defects of the red cell as opposed to those that result from extrinsic events that are not necessarily related to the structure of the red cell but affect its life span. Intrinsic defects of the red cell relate to inherited deficiencies of the red cell membrane, hemoglobin structure or synthesis, or biochemical components. Extrinsic defects relate to those events that are secondary to red cell structure and function but may still result in a hemolytic event. Regardless of the classification, it is paramount that the hemolytic anemias be recognized, evaluated, and managed so that life-threatening sequelae do not arise.9 See Table 4.3 for a modified list of those anemias classified by intrinsic or extrinsic defects.
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