Diagnosis of erythrocyte glucose-6-phosphate dehydrogenase deficiency in the negro male despite hemolytic crisis.

E RYTHROCYTE GLUCOSE-6-PHOSPHATE DEHYDROGENASE ( G-6PD ) DEFICIENCY is a frequent clinically-significant genetically-determined abnormality of man. On the basis of gene frequency of the enzyme deficiency, about 3,000,000 Negroes in the United States carry genes for this disorder.1 When exposed to certain drugs and chemical agents, clinically normal persons with G-6-PD deficiency experience hemolysis.2 The diagnosis of G-6-PD deficiency in the Negro is often made difficult by falsely-normal estimates of red cell enzyme activity during acute hemolytic crisis. The distribution of enzyme activity in the red cell population is age dependent, with increased activity in the younger red cells and decreased activity in the older red cells.2 Since susceptibility of red cells to chemical agents in this disorder is inversely proportional to enzyme activity, the older cells with the least G-6-PD activity are preferentially eliminated in hemolytic crisis, leaving a disproportionate number of young red cells with high enzyme levels.3 Measurement of red cell G-6-PD activity in whole blood samples during hemolytic crisis may result in values in the normal range. Proper recognition of G-6-PD deficiency is therefore usually postponed until the hemolytic episode and its reticulocytic response have subsided.35 To make possible the recognition of G-6-PD deficiency despite hemolytic crisis, we have employed a simple technique based on density changes associated with red cell aging,6’7 for detecting the persisting, aged, enzymedeficient erythrocytes in Negro patients with chemically induced hemolytic anemia who have not received blood transfusions within the past five months.