What is the pathophysiology of glucose-6-phosphate dehydrogenase (G6PD) deficiency?

Updated: Feb 19, 2019
  • Author: Srikanth Nagalla, MBBS, MS, FACP; Chief Editor: Emmanuel C Besa, MD  more...
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Answer

The G6PD enzyme is part of the pentose monophosphate shunt. It catalyzes the oxidation of glucose-6-phosphate and the reduction of nicotinamide adenine dinucleotide phosphate (NADP+) to nicotinamide adenine dinucleotide phosphate (NADPH). NADPH maintains glutathione in its reduced form, which acts as a scavenger for dangerous oxidative metabolites.

The pentose monophosphate shunt is the only source for NADPH in red blood cells. Therefore, red blood cells depend on G6PD activity to generate NADPH for protection. Thus, red blood cells are more susceptible to oxidative stresses than other cells. In persons with G6PD deficiency, oxidative stresses can denature hemoglobin and cause intravascular hemolysis. Denatured hemoglobin can be visualized as Heinz bodies in peripheral blood smears processed with supravital staining. Heinz bodies are shown in the figure below.

Heinz bodies in a peripheral smear stained with a Heinz bodies in a peripheral smear stained with a supravital stain. Heinz bodies are denatured hemoglobin. Denatured hemoglobin occurs in G6PD deficiencies and in unstable hemoglobin disorders.

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