The role of glucose-6-phosphate dehydrogenase activity testing is primarily to diagnose hemolysis due to defects in this enzyme or to differentiate it from other diseases that cause hemolysis. Glucose-6-phosphate dehydrogenase (G6PD) is an important rate-limiting enzyme in erythrocyte hexose phosphate bypass metabolism and plays a key role in protecting cells from oxidative stress. When erythrocytes are deficient in G6PD, erythrocyte peroxidative damage can lead to erythrocyte destruction and hemolysis. The main manifestations of hemolysis due to G6PD deficiency are neonatal hyperbilirubinemia, serosanguineous disease, congenital nonspherocytic erythrocytic hemolytic anemia, and drug- or infection-induced acute hemolytic anemia. The vast majority of G6PD deficiencies are not clinically manifest and acute hemolysis occurs after exposure to infection or drugs, and diabetic ketoacidosis can also induce G6PD-deficient red blood cell destruction. The diagnosis of G6PD deficiency can be confirmed by testing for G6PD activity, or by differentiating it from other diseases that cause hemolysis. Consult your doctor for more information.