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

• Intrinsic

  • Membrane defects

    • Hereditary spherocytosis

    • Hereditary elliptocytosis

    • Paroxysmal nocturnal hemoglobinuria

  • Glycolytic defects

    • Pyruvate kinase deficiency

    • Severe hypophosphatemia

  • Oxidation vulnerability

    • Glucose-6-phosphate dehydrogenase deficiency

    • Methemoglobinemia

  • Hemoglobinopathies

    • Sickle cell syndromes

    • Thalassemia

    • Unstable hemoglobins

    • Methemoglobinemia

• Extrinsic

  • Immune

    • Autoimmune

    • Lymphoproliferative disease

    • Drug-induced

  • Microangiopathic

    • Thrombotic thrombocytopenic purpura

    • Hemolytic-uremic syndrome

    • Disseminated intravascular coagulation

    • Valve hemolysis

    • Metastatic adenocarcinoma

    • Vasculitis

    • Copper overload

  • Drug-induced

  • Infection

    • Plasmodium

    • Clostridium

    • Borrelia

  • Hypersplenism

  • Burns

CLINICAL FINDINGS

• Symptoms of anemia

• Jaundice, pigment gallstones, cholecystitis in chronic cases

• Palpable spleen

DIAGNOSIS

• Serum haptoglobin is low but test is neither specific nor sensitive

• Reticulocytosis present unless second disorder (infection, folate deficiency) is superimposed on hemolysis

• 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

• Hemoglobinemia and methemalbuminemia if severe intravascular hemolysis

• Indirect bilirubin elevated, total bilirubin may rise to 4 mg/dL or more; higher bilirubin elevations may indicate hepatic dysfunction

• Serum lactate dehydrogenase elevated in microangiopathic hemolysis; may be elevated in other hemolytic anemias

TREATMENT

• See Treatment of Specific Anemias

• Folic acid, 1 mg orally once daily

• Transfusions possible