Anemia, Hemolytic

KEY FEATURES

• Reticulocytosis is important clue to presence of hemolysis

• Generally classified according to whether the defect is intrinsic or extrinsic to the red blood cell (Table 15–8)

• Intrinsic

  • Membrane defects

  • Glycolytic defects

  • Oxidation vulnerability

  • Hemoglobinopathies

• Extrinsic

  • Immune

  • Microangiopathic

  • Drug-induced

  • Infection

  • Hypersplenism

  • Burns

DIAGNOSIS

• Serum haptoglobin level

  • Depressed in hemolytic disorders

  • Not always a reliable indicator of hemolysis, particularly in end-stage liver disease (its site of synthesis)

• Reticulocytosis present unless second disorder is superimposed on hemolysis

  • Infection

  • Inflammation

  • Nutritional deficiency

  • Disturbed marrow

• Transient hemoglobinemia with intravascular hemolysis

• Hemoglobinuria when capacity for reabsorption of hemoglobin by renal tubular cells is exceeded

• Urine hemosiderin test positive; indicates prior intravascular hemolysis

• If severe intravascular hemolysis

  • Hemoglobinemia

  • Methemalbuminemia

• Bilirubin

  • Indirect bilirubin elevated

  • Total bilirubin may rise to 4 mg/dL or more

  • Higher bilirubin elevations may indicate hepatic dysfunction

• Serum lactate dehydrogenase

  • Strikingly elevated in microangiopathic hemolysis

    • Thrombotic thrombocytopenic purpura

    • Hemolytic-uremic syndrome

  • May be elevated in other hemolytic anemias

TREATMENT

• See Treatment of Specific Anemias