Background: Hypothyroidism is a risk factor in atherosclerotic cardiovascular diseases, but there is controversy in effect of subclinical hypothyroidism on cardiovascular diseases. Measuring intimal medial thickness by ultrasound is accepted method of detection of early atherosclerotic changes, which has been proven to be directly related to coronary artery disease.
Aims and Objectives: We aim to estimate the relation between subclinical hypothyroidism and endothelial dysfunction and the effects of levothyroxine therapy on it.
Materials and Methods: Fifty newly diagnosed subclinical hypothyroidism cases aged 18-65 years were taken from out and in patients Departments of medicine of Hamidia Hospital, Bhopal from December 2015 to December 2016. The clinical examination consisted of relevant medical history, physical examination measurement like height, weight, body mass index (BMI), and waist hip ratio, systolic and diastolic blood pressure. Blood sampling for measurement of hemoglobin, total leukocyte count (TLC), T3, T4, thyroid stimulating hormone (TSH) and lipid profile consisting of total cholesterol, low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), triglycerides (TG) was obtained. Carotid intima media thickness (CIMT) was measured before and after 6 months of levothyroxine therapy.
Results: Female preponderance was observed (80.39%) and most common age was 30-40 years (58.82%). CIMT in both of the right (Z=-3.923, p<0.001) and left carotid artery (Z=-3.31, p=0.001) have reduced significantly with levothyroxine replacement therapy. Weight (r=0.288,p=0.041), BMI (r=0.283, p=0.044), WHR (r=0.332, p=0.017) TSH (r=0.393, p=0.017) and LDL-C (r=0.409, p=0.003) had a positive correlation with CIMT-Right and WHR (r=0.285, p=0.043), TSH (r=0.357, p=0.039) and LDL-C (r=0.287, r=0.041) had the a positive correlation with CIMT-Left. In a multivariate regression model, only Waist Hip Ratio (p=0.012) and TSH (p=0.049) were found as significant predictor of change in CIMT in right carotid artery whereas only Waist Hip Ratio (p=0.011) were found as significant predictor of change in CIMT in left carotid artery.
Conclusion: Levothyroxine treatment does reduce the CIMT in patients with subclinical hypothyroidism and therefore improves markers associated with cardiovascular disease and decreases cardiovascular morbidity.