Role of Insulin, Homeostatic Model Assessment - Insulin Resistance with Lipid Profile Test to Evaluate Cardiovascular Disease Risk in Thyroid Disorder Patients

Aims: To find out role of insulin, homeostasis model assessment for insulin resistance (HOMA-IR) with lipid profile test in evaluation of cardiovascular disease risk in thyroid disorder patients.

Study Design: An analytical case control study.

Place and Duration of Study: Department of Biochemistry, School of Health and Allied Sciences, Pokhara University, between November 2013 and February 2014.

Methodology: The study encompassed of 90 subjects; 30 randomly selected healthy volunteers and 30 Hypothyroid and 30 Hyperthyroid subjects selected from different Hospital of Pokhara. The participants were identified as hypothyroid and hyperthyroid relying in serum FT3, FT4 and TSH levels, clinical history and medication. The participants were asked to fill the questionnaire, 5 ml of the venous blood was collected the measurement of thyroid hormones (FT3, FT4 and TSH), serum lipid profile (TC, TG, HDL, LDL, VLDL) and serum Insulin.

Results: The mean value of FT3, FT4, TSH of control subjects were 2.5±0.63 (pg/ml), 1.39±0.28 (ng/dl), 2.82±1.75 (umol/ml), hyperthyroid subjects were 2.18±0.88 (pg/ml), 0.96±0.32 (ng/dl), 24.28±19.8 (umol/ml) and hypothyroid subjects were 4.52±1.72 (pg/ml), 3.36±3.61 (ng/dl), 0.156±0.14 (umol/ml) respectively. The mean value of serum total cholesterol (TC), triglyceride (TG), high density lipoprotein (HDL), low density lipoprotein LDL cholesterol and vary low density lipoprotein (VLDL) were greatly increased in hypothyroid subjects 240 (mg/dl), 194.7(mg/dl), 49.63, 151.51 and 38.78 (mg/dl) respectively as compared to control 166.59 (mg/dl), 151.07 (mg/dl), 50.23, 86.05 and 30.21 (mg/dl) respectively and hyperthyroid subjects 62.13 (mg/dl), 131.61(mg/dl), 45.o7, 90.75 and 26.32 (mg/dl) respectively. An increase in serum insulin level is in both hypothyroid 32.78 (uIU/mL) and hyperthyroid 30.08 (uIU/mL). HOMA-IR was significantly associated with TC, TG and LDL. Spearman’s correlation analysis of insulin with TC, LDL Cholesterol, TG and VLDL that of HOMA-IR with TC and LDL while insulin with TC /HDL ratio, LDL Cholesterol and TC also HOMA-IR with TC /HDL and LDL Cholesterol shows significant correlation.

Conclusion: Thyroid dysfunction has a great impact on lipid profile as well as a number of other cardiovascular disease (CVD) risk factors. There is a close relation between IR and thyroid hormones. The insulin resistance in present in hypo and hyperthyroid patients and thyroid dysfunctions induce significant changes in lipid profile. Therefore estimation of traditional lipid profile along with some additional parameters like serum insulin, IR helps to assess the thyroid status. Lipid profile test along with insulin and HOMA-IR can also help in the early evaluation of possible risk of CVD in thyroid disorder patients.