A Guide to G6PD Deficiency

Glucose-6-phosphate dehydrogenase (G6PD) is an enzyme involved in the pentose phosphate pathway and maintaining levels of co-enzyme nicotinamide adenine dinucleotide phosphate (NADPH). NADPH in turn maintains appropriate levels of glutathione, responsible for protecting red blood cells from oxidative damage¹.

Those who suffer from the X-linked deficiency are predisposed to hemolytic anemia, because of the breakdown of red blood cells when cells are exposed to oxidative stress. The severity of the condition depends on the enzyme variant²

· Severe (I): chronic non-spherocytic hemolytic anemia³

· Severe (II): less than 10% of normal enzyme activity

· Moderate (III): 10% to 60% of normal enzyme activity

· Mild to none (IV): 60% to 150% of normal enzyme activity

· None (V): greater than 150% of normal enzyme activity

Hemolysis can occur after to exposure to certain bacterial or viral infection, drugs, or foods. Individuals of Mediterranean descent have very low levels of G6PD activity, while African-Americans possess 5% to 15% of normal G6PD activity.

Drugs and foods associated with oxidative hemolysis include ascorbic acid; aspirin; dapsone; dimercaprol; fava beans; methylthioninium chloride-methylene blue; nitrofurantoin; prilocaine; primaquine; quinolones; and sulfonamides, including bactrim.

Exams may be done to diagnose and manage G6PD deficiency, including a complete blood count and G6PD enzyme activity. Avoiding drugs or foods associated with hemolysis is essential for those with G6PD deficiency. Individuals are advised to carry a G6PD deficiency alert bracelet. Treatment for severe episodes upon exposure may include blood transfusions.

References

1. Luzzatto L, Nannelli C, Notaro R. Glucose-6-phosphate dehydrogenase deficiency. Hematol Oncol Clin North Am. 2016;30(2):373-93. doi: 10.1016/j.hoc.2015.11.006.

2. Frank JE; Diagnosis and management of G6PD deficiency. Am Fam Physician. 2005;72(7):1277-82

3. Gallegher PG. Hemolytic anemias: red cell membrane and metabolic defects: In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Elsevier Saunders; 2016:164.