RBC enzyme defects

• RBCs can’t handle oxidative damages as well

• Can come about from abnormalities in the hexose shunt or in glutathione metabolism

• The most frequent cause is G6PD decrease

  • G6PD-A^- is found in 10% of American blacks and causes mild hemolysis with exposure to oxidants like quinacrine, sulfonamides, etc

  • G6PD-Mediterranean produces more severe hemolysis

  • Both are X-linked; gene persistence through anti-malarial effect

  • Pitting of Heinz bodies (little clusters of altered Hb) from affected RBCs by the RES leads to the formation of schizocytes (“bite cells”), spherocytes, and eventual hemolysis

  • A diagnosis may be suggested by a (+) Heinz body stain (crystal violet, which stains denatured Hb) and confirmed by measuring G6PD levels

• Other enzymopathies include deficiencies of pyruvate kinase, hexokinase, and glutathione synthetase

Category: Medical Subject Notes , Pathology Notes