Low Hemoglobin A1c (HbA1c) Revealing Hemolytic Anemia in a Growth Hormone-Treated Child: A Case Report

Hemoglobin A1c (HbA1c) is widely utilized for monitoring glycemic control in diabetes mellitus. Growth hormone (GH) therapy necessitates regular glucose monitoring due to an increased risk of diabetes. However, hemolytic anemia may result in spuriously low HbA1c levels due to a shortened erythrocyte lifespan, potentially leading to misinterpretation of glycemic status. We report an 11-year-old girl with GH deficiency undergoing GH therapy who presented with an abnormally low HbA1c level of 3.9% despite normal glucose tolerance. Laboratory tests revealed mild anemia (hemoglobin: 11.8 g/dL), elevated total bilirubin (1.27 mg/dL), and undetectable haptoglobin (<10 mg/dL), suggesting ongoing hemolysis. Osmotic fragility testing revealed erythrocyte sensitivity to hemolysis, which was more pronounced in incubated blood than in fresh blood. Although a definitive diagnosis remained elusive owing to the lack of Coombs testing and genetic analysis, hereditary spherocytosis (HS) was considered the most likely etiology, particularly given the epidemiological prevalence of congenital hemolytic disorders in Japan. Due to unreliable HbA1c values, glycoalbumin was used as an alternative marker for glucose monitoring, demonstrating normal levels (13.7%). This case highlights the need to consider hemolytic anemia in pediatric patients undergoing GH therapy who present with unexpectedly low HbA1c values. In such cases, glycoalbumin may serve as a reliable alternative marker for assessing glucose metabolism.