The Effect of Thyroid Hormone Replacement on theMetabolic Control and Insulin Resistance in Patients withSubclinical Hypothyroidism

Studying the treatment effect of subclinical hypothyroidism in decreasing metabolic syndromerisk factors and cardiovascular diseases is necessary and can be helpful to control future disorders. In spite ofvarious studies, the relationship between subclinical hypothyroidism and cardiovascular diseases remain con-troversial. Studies which consider the effects of subclinical hypothyroidism treatment on metabolic control andinsulin resistance have not been done in the Islamic Republic of Iran yet.

In this inter-ventional study, 153 patients with subclinical hypothyroidism (thyroid stimulation hormone (TSH) >5, normalT3 and T4 at least 2 times) were selected from Labbafinejad endocrine clinic. Laboratory tests were performedat 8 a.m. after 12-14 hours fasting. Patients were then treated with levothyroxine (25-50μg daily). To adjustthe dose, thyroid function tests (TFT) were checked every 2 months for 6 months. Collected data was usedfor analysis by spss18 software.

After 6 months treatment of subclinical hypothyroidism mean valuesimproved in factors such as insulin resistance profile (fasting blood sugar (FBS), 2 hours post prandial (2hPP),fasting insulin and homeostasis model assessment estimated insulin resistance (HOMA-IR index), lipid profile(total cholesterol, low density lipoprotein (LDL) and high density lipoprotein (HDL), decreased c-reactive pro-tein (CRP) and weight (all had P value<0.05). Treatment did not have significant effect on triglycerides (TG),waist circumference, body mass index (BMI), uric acid ad systolic/diastolic blood pressure (p values>0.05). Butthe number of cases with high systolic/diastolic blood pressure decreased significantly after 6 months treat-ment (P values=0.007 and 0.01).

Subclinical hypothyroidism treatment is suggested according tomentioned effects, especially in cases with insulin resistance, lipid profile disturbance, obesity, and high bloodpressure.