Glucose-6-phosphate dehydrogenase deficiency (G6PD deficiency)
- NADPH is necessary to keep glutathione reduced, which in turn detoxifies free radicals and peroxides. ↓ NADPH in RBCs leads to hemolytic anemia due to poor RBC defense against oxidizing agents (eg, fava beans, sulfonamides, nitrofurantoin, nalidixic acid, chloramphenicol, primaquine/chloroquine, antituberculosis drugs, vitamin K analogs, ASA, benzene, naphthalene). Infection (most common cause) can also precipitate hemolysis; inflammatory response produces free radicals that diffuse into RBCs, causing oxidative damage.
- X-linked recessive disorder; most common human enzyme deficiency; more prevalent among African Americans. ↑ malarial resistance.
- Heinz bodies—denatured globin chains precipitate within RBCs due to oxidative stress.
- Bite cells—result from the phagocytic removal of Heinz bodies by splenic macrophages. Think, “Bite into some Heinz ketchup.”
- Infants may have prolonged neonatal jaundice (beyond 2 weeks) due to increased erythrocyte breakdown and immaturity of the newborn liver.