A Study on Lipid Abnormalities in Hyperthyroidism and their Response to Antithyroid Drugs

Abstract

Introduction: Alterations in various lipid parameters have been reported in patients with thyroid dysfunction but the evidence is controversial. The magnitude of changes in plasma Low Density Lipoprotein (LDL) and High Density Lipoprotein (HDL) levels after restoration of the euthyroid state varies from patient to patient and depends on multiple factors including the severity and duration of the thyroid dysfunction and the presence of any pre-treatment primary lipid disorder apart from diet and body weight. In addition, Asians have dyslipidemia at a lower Body Mass Index (BMI) than Western population and the effect of thyroid disorders and response to treatment may also be different. Aim: To explore the relationships between hyperthyroidism and the lipid profile of patients and the response to antithyroid drugs. Materials and Methods: A case-control study was conducted over one year, in 57 newly diagnosed patients with hyperthyroidism and 57 control subjects. All patients and controls had thyroid hormone and Thyroid Stimulating Hormone (TSH) levels and fasting lipid profile; the patients had a repeat fasting lipid profile after restoration of euthyroid state with antithyroid drug. The data was analysed using IBM-Statistical Package for the Social Sciences (SPSS) version 21.0. Results: The mean age of patients (34.7±10.93 years) and controls (32.3±10.75 years) were comparable (p=0.239). Hyperthyroid patients presented with significantly lower serum levels of Total Cholesterol (TC), (125±29.7 mg/dL), LDL, (74.7±19.43 mg/dL), HDL, (37.8±7.87 mg/dL), Triglycerides (TG), (123.2±64.5 mg/ dL) and Very Low Density Lipoprotein Cholesterol (VLDL-C), (24.6±12.91 mg/dL) than the control subjects- 174.6±34.68 mg/ dL, 109.3±23.4 mg/dL, 41.35±7.56 mg/dL, 157.2±86.21 mg/dL and 31.4±17.28 mg/dL respectively (p<0.05). All the patients were treated with carbimazole; with a mean starting dose of 33.2±6.59 mg/day. Post-treatment, after achieving euthyroidism, the mean levels of TC, LDL, HDL, TG, VLDL of the patients were significantly higher than pre-treatment value (p<0.05). Significant negative correlation was seen between serum thyroxine and LDL (p<0.04) and TSH and HDL (p<0.001), once patients achieved control of thyrotoxicosis. Conclusion: There was significant decrease in lipid parameters in hyperthyroid state which showed improvement after achieving control of thyrotoxicosis with carbimazole.

Keywords

• carbimazole
• graves’ disease
• lipid profile