Hemolytic Anemia: Definition, Diagnosis, and Complications

Hemolytic Anemia

• Hemolytic anemia is a type of anemia that results from the shortened survival of RBCs.
• Normally, the life span of RBCs is 100-120 days, with about 1% of RBCs being removed from the circulation each day and replaced by an equal number of new cells from the bone marrow.

General Features of Hemolytic Anemia

• Anemia: the degree of anemia depends on the rate of hemolysis and the efficiency of bone marrow.
• Jaundice: unconjugated hyperbilirubinemia due to bilirubin overload, usually mild as the liver can increase its capacity to conjugate bilirubin several folds.
• Hepatosplenomegaly: occurs due to hemosiderosis and extramedullary hematopoiesis, with the liver and spleen being enlarged.
• Characteristic skeletal manifestations:
  • Expansion of the medullary spaces of the skull and hands.
  • Abnormal mongoloid facies.
  • Prominence of malar eminences.
  • Frontal bossing.
  • Depression of the nose and exposure of the upper central teeth.

Investigations of Chronic Hemolytic Anemia

• Indirect evidences of hemolysis:
  • Sustained reticulocytosis with low hemoglobin level.
  • Lowering or reversal of the myeloid/erythroid ratio in the bone marrow.
  • Blood chemistry:
    • Unconjugated hyperbilirubinemia.
    • Increased serum iron.
    • Diminished iron binding capacity.
    • Decreased plasma concentration of haptoglobin and hemopexin.
  • Stool: increased stercobilinogen.
  • Urine: increased urobilinogen.
  • Characteristic X-ray findings:
    • Hair-on-end appearance on skull radiograph due to widening of the diploic spaces.
    • Loss of the waist of the metacarpal bones (balloning) with rarefaction.
• Direct evidences of hemolysis:
  • Determination of RBCs life span by injection of radioactive chromium (51Cr) tagged RBCs into the circulation.
  • Identification of free hemoglobin in the plasma and urine (indicates intravascular hemolysis after saturation of the binding proteins).

Complications of Hemolytic Anemia

• Hemosiderosis and increased body iron:
  • Short life span of RBCs.
  • Frequent blood transfusion.
  • Increased intestinal iron absorption.
• Manifestations of hemosiderosis:
  • Myocardium: uncontrolled heart failure.
  • Liver: liver cirrhosis.
  • Endocrinal dysfunction:
    • Pancreatic dysfunction: diabetes mellitus.
    • Pituitary affection: growth retardation.
    • Gonadal dysfunction: delayed puberty.
    • Adrenal gland: adrenal failure.
    • Thyroid and parathyroid dysfunction.
• Gallstones:
  • Pigmented gallstones formed of calcium bilirubinate.
  • Develops usually after the age of 4 years.
• Anemic heart failure.
• Complications of blood transfusion: hepatitis, AIDS.
• Aplastic crisis:
  • Episodes of bone marrow failure manifest by severe anemia and reticulocytopenia.
  • Usually precipitated by viral infection.
• Hypersplenism:
  • An enlarged spleen with increasing demand for blood transfusion.
  • Depression of one or more of cellular elements of blood.
  • Active formation of that element in the bone marrow.

Hereditary Spherocytosis

• Etiology:
  • Autosomal dominant trait.
  • Genetic abnormality of proteins (spectrin or ankyrin) responsible for RBCs shape.
• Clinical features:
  • Positive family history.
  • Presents in newborn (50% of cases) with anemia and jaundice that may need exchange transfusion and phototherapy.
  • Other manifestations of chronic hemolytic anemia.
  • Pigment stones may lead to obstructive jaundice.
  • Splenomegaly.
• Investigations:
  • Laboratory data of chronic hemolytic anemia.
  • Anemia: mild to moderate.
  • MCV: usually normal.
  • MCH: raised.
  • Reticulocytosis.
  • Peripheral blood smear: shows spherocytes.
  • Osmotic fragility test: shows increased fragility of spherocytes in hypotonic saline.

Treatment of Hereditary Spherocytosis

• Splenectomy: recommended after age 5-6 years to avoid the risk of postsplenectomy sepsis in younger children.
• Folic acid supplement: 1mg/day.
• With severe anemia, aplastic crisis, and poor growth: repeated transfusions are necessary.

Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency

• Etiology:
  • Sex-linked recessive mode of inheritance.
  • G6PD enzyme is necessary to prevent oxidant damage of the RBCs.
  • Hemolysis does not occur spontaneously but after exposure to certain drugs, ingestion of fava beans, inhalation of pollens of fava plant (favism), and infections.
• Agents precipitating hemolysis:
  • Antibacterials.
  • Vitamin K analogs.
  • Acetylsalicylic acid.
  • Chemicals: Naphthalene and benzene.
  • Illness: DM, hepatitis.
• Clinical manifestations:
  • Acute onset of pallor, jaundice, red urine, and fever within 48 hours of exposure to precipitating factors.
  • Anemic heart failure or acute renal failure may also occur.
• Diagnosis:
  • Indirect evidences of hemolysis.
  • Marked anemia.
  • Supravital preparation of the red cells: reveals Heinz bodies.
  • Reticulocytosis during recovery.
  • Unconjugated hyperbilirubinemia.
  • Hemoglobinuria.
  • Direct measurement of the enzyme activity.

Treatment of G6PD Deficiency

• Prevention of hemolysis by avoiding the offending agents.
• Acute attack:
  • Blood transfusion.
  • Fluid and alkali therapy to avoid renal failure.

This quiz covers the definition, general features, diagnosis, and complications of hemolytic anemia, as well as specific information on hereditary spherocytosis. Learn about the etiology, clinical features, investigations, and treatment of this condition.