Elevation of HbA1C in Non-diabetic Hypothyroid Individuals: Is Anaemia the Connecting Link? -A Preliminary Study

Abstract

Studies have shown elevated HbA1C in non-diabetic hypothyroid patients. Hypothyroid patients often show anaemia as an associated feature which is an another condition showing falsely elevated A1C. Hence this study is aimed to investigate whether elevated A1C in hypothyroidism can be attributed to anaemia. HbA1C levels of 120 non-diabetic hypothyroid patients (30 microcytic hypochromic anaemia, 30 normocytic normochromic anaemia and 60 non anemic patients) with 120 age, sex, plasma glucose levels and anaemia status matched controls were assessed. Anaemia status was determined by ferritin, Haemoglobin, red cell indices and peripheral smear. Glycemic status was determined by fasting Plasma glucose. HbA1C levels in hypothyroid patients with hypochromic microcytic anaemia and normocytic normochromic anaemia were 6.82 ± 0.71% & 6.32 ± 0.75% against 6.43 ± 0.43% & 5.87 ± 0.46 % of euthyroid anaemia matched controls respectively. While hypothyroid non anemic patients showed A1C levels of 5.91 ± 0.31% against 5.46 ± 0.62% of euthyroid non anemic controls. Hypothyroid Patients with anaemia had a significant odds ratio 3.16 (95% CI 1.426-7.016) for HbA1C > 6.5. Non-diabetic hypothyroid individuals with anaemia shows elevate A1C levels in prediabetes range. Hence care should be excercised while using HbA1C as a diagnostic tool for diabetes in such patients.