Two Patients with Low HbA1c Levels Due to Subclinical Hemolysis

Abstract

We experienced two patients with low HbA1c levels due to subclinical hemolysis. One patient did not present with diabetes mellitus, whereas the other patient exhibited diabetes mellitus; in both cases, the glycated albumin to HbA1c ratio was extremely high. Since the HbA1c levels measured using the HPLC method and an immunoassay were identical in both patients, the possibility of variant hemoglobin was excluded. Although neither subject was anemic, the levels of haptoglobin and reticulocytes were low and high, respectively. A morphological examination of the erythrocytes revealed elliptocytes in one patient and spherocytes in the other patient according to smears of the peripheral blood and scanning electron microscopy. These findings indicated that the cause of the low HbA1c levels was subclinical hemolysis resulting from elliptocytosis and spherocytosis, respectively. Subclinical hemolysis should thus be considered in patients with apparently low HbA1c levels.