G6PD Deficiency

GENERAL PRINCIPLES

G6PD deficiency represents the most common disorder of RBC metabolism worldwide. Deficiency of G6PD renders RBCs more susceptible to oxidative damage through decreased glutathione reduction, leading to chronic or acute episodic hemolysis in the presence of oxidative stress.

Classification

More than 400 variants of G6PD are recognized. The severity of hemolysis depends on the degree of deficiency present.

Epidemiology

• X-linked inheritance; the degree of involvement in females is dependent on lyonization.

• G6PD is felt to be protective against malaria, accounting for its prevalence in malaria-endemic areas.

• Hemolysis is triggered by exposure to mediators of oxidative stress, infections, and fava beans. Patients being considered for medications that trigger G6PD-dependent hemolysis should be tested for a deficiency before starting the drug.

DIAGNOSIS

• Diagnosis is determined by measuring G6PD activity in RBCs from a peripheral blood sample. Peripheral smear may show bite cells and blister cells. Direct coombs test will be negative.

• False-negative results may occur in patients with a recent episode of hemolysis or in patients recently

transfused because these cells have higher levels of G6PD.

TREATMENT

• In the most common form of G6PD deficiency, hemolytic episodes tend to be self-limiting; the mainstay of treatment is supportive. If acute hemolytic anemia is severe, blood transfusion may be needed.

• The underlying cause of oxidative stress should be addressed (i.e., treatment of infection, removal of drug).