Challenges in Glycemic Monitoring: Undetectable HbA1c Level in an Asymptomatic Patient With Hemoglobin E and Beta-Thalassemia Minor: A Case Report.

Glycated hemoglobin (HbA1c) is a laboratory examination recommended by the American Diabetes Association to monitor blood glucose levels in patients with diabetes mellitus. This gold standard method for testing HbA1c uses highperformance liquid chromatography (HPLC). One advantage of HbA1c testing with HPLC is the ability to detect Hb variants or hemoglobinopathies, although HbA1c results may become irrelevant in such conditions. A 49-year-old female patient came to the Ophthalmology Outpatient Clinic of Dr. Soetomo Hospital due to visual impairment in both eyes and plans for cryotherapy surgery. In preparation for the surgery, laboratory tests were performed with results of haemoglobin 12.1 g/dL, mean corpuscular volume 58.9 fL, mean corpuscular haemoglobin 19.3 pg, leukocytes 13,370/uL, platelets 399,000/uL and random blood glucose 127 mg/dL; however, HbA1c was not detected. In the HbA1c test, a 93.7% window variant was obtained. Based on blood smear evaluation, there was hypochromic microcytic anisopoikilocytosis with target cells. The electrophoresis results revealed HbA 0.7%, HbF 0.6%, HbE 94.9% and HbA2 4.7%, indicating the presence of beta thalassemia with hemoglobinopathy E. The diagnosis of hemoglobinopathy E is based on a complete blood count, peripheral blood smear and haemoglobin electrophoresis. HbA1c examination by HPLC can yield undetectable HbA1c levels in hemoglobinopathies. Monitoring blood glucose levels in such cases is also irrelevant when using HbA1c, because red blood cells have a shorter lifespan in the presence of Hb variants. Glucose monitoring in this condition can be done by periodic glucose examination, fructosamine, or glycated albumin. The HbA1c test cannot be used as a marker of glucose control in patients with hemoglobinopathy E.