Impact of Levothyroxine on Lipid Profile in Patients with Hypothyroidism

Hypothyroidism is a common endocrine disorder and requires lifelong treatment. Hypothyroidism is often associated with dyslipidemia in some populations. The present study was designed to evaluate the impact of levothyroxine (LT₄) on lipid profile in hypothyroid patients. This cross-sectional analytical study was conducted in the Department of Pharmacology & Therapeutics, Rajshahi Medical College in collaboration with the Institute of Nuclear Medicine and Allied Sciences (INMAS), Rajshahi from July 2018 to June 2019 to compare serum total cholesterol (TC), serum triglyceride (TG), serum LDL-C and serum HDL-C levels among euthyroids, newly diagnosed hypothyroid patients and levothyroxine (LT₄) treated hypothyroid patients. A total of 30 patients with newly diagnosed hypothyroidism and an equal number of age-matched healthy controls (n=30, control group) of both sexes were recruited in the present study. Thirty (30) hypothyroid patients were reevaluated after 6 month of LT₄ therapy. The fasting blood samples were collected from the subjects for the estimation of lipid profile. Significantly higher values were observed in total cholesterol (TC) 198.5±19.2mg/dl, triglycerides (TG) 147.0±14.5mg/dl, low density lipoprotein cholesterol (LDL-C) 133.9±19.7mg/dl (p<0.001) and a significant decreased value was seen in high density lipoprotein-cholesterol (HDL-C) levels (35.1±3.67mg/dl) in newly diagnosed hypothyroid patients as compared to after LT₄ therapy and normal healthy individuals (p=0.009). These observations suggest that people with hypothyroidism have high risk of development of atherosclerosis which may lead to coronary heart diseases (CHD) due to persistent dyslipidemia. Hypothyroidism induces dyslipidemia or expedites the process of existing dyslipidemia, LT₄ therapy corrects it to a significant level thus reduce the risk for atherosclerosis.