A case of hereditary xerocytosis diagnosed as a result of suspected hypoglycemia and observed low glycohemoglobin.

Hereditary xerocytosis is a primary erythrocyte disorder in which a defect in the erythrocyte membrane leads to potassium efflux from the cell. An osmotic shift of water from the intracellular compartment follows, resulting in decreased deformability of the cell, increased membrane rigidity, hemolysis, decreased average duration of erythrocyte survival, and reticulocytosis. The condition is inherited as an autosomal dominant trait. In this publication, we report the case of a patient who presented with a vague history compatible with hypoglycemia and was found to have a low glycohemoglobin level. Further workup led to a diagnosis of hereditary xerocytosis in this patient and in other members of the family. This case illustrates the importance of understanding the underlying variables that affect the results of all commonly used glycohemoglobin assays, including determination of hemoglobin A(1C) and how primary red-cell disorders may alter its value.