Glucose 6-phosphate dehydrogenase (G6PD) deficiency

Glucose 6-phosphate dehydrogenase (G6PD) deficiency is a deficiency of the rate-limiting enzyme of the pentose phosphate pathway, which is essential for preventing oxidative damage to RBCs. Deficient RBCs are susceptible to haemolysis when exposed to oxidants. It’s an X-linked condition.

Like the haemoglobinopathies it’s most common in Africa, Asia and the Mediterranean. The enzyme G6PD is important to regenerate glutathione, an important antioxidant.

Most patients are asymptomatic until they’re exposed to factor which precipitates oxidative injury and resulting haemolysis. This can occur due to infection, fava beans, and certain drugs like sulphonamides. During these haemolytic crises, Hb drops rapidly, possible falling below 50 g/L over 1 – 2 days. Symptoms of crisis include jaundice, pallor, dark urine, and abdominal or back pain.

G6PD deficiency causes normocytic haemolytic anaemia. On blood smear, bite cells and Heinz bodies may be present. Measurement of the G6PD enzyme activity in RBCs confirms the diagnosis. Management involves avoiding triggers of haemolytic crises.