Aim: We aimed to demonstrate the interference in Hemoglobin A1c (HbA1c) testing in a patient diagnosed with Evans syndrome, a rare condition characterized by autoimmune hemolytic anemia.

Case: A patient who presented to our laboratory for biochemical evaluation was found to have an HbA1c level below the detection limit (<3%) when measured by high-performance liquid chromatography (HPLC). Since the HbA1c result was inconsistent with the patient’s previous blood glucose levels, an alternative method was employed to rule out potential analytical interference. The HbA1c level measured by the immunoturbidimetric method was also below the detection limit (<4%). A detailed review of the patient’s clinical file revealed a diagnosis of Evans syndrome, characterized by autoimmune hemolytic anemia.

Result: It should be noted that in patients with autoimmune hemolytic anemia, falsely low HbA1c results may occur regardless of the analytical method used.