Changes in Lipid Profile and Body Mass Index in Patients with Subclinical Hypothyroidism: Evaluation of L-Thyroxine Treatment

Introduction: Subclinical hypothyroidism is defined as a mild elevation in serum thyroid stimulating hormone (TSH) level, while serum free T4 (FT4) and free T3 (FT3) levels are within the reference range. The main problem with these patients is whether they should receive therapy or not. In many studies, positive effects of levothyroxine treatment on hypothyroidism symptoms, serum lipid levels and cardiac functions are shown. In this prospective clinical study, we aimed to evaluate the metabolic changes in newly diagnosed subclinical hypothyroidism patients who were administered thyroxine. Methods: Sixty-three newly diagnosed patients with subclinical hypothyroidism were included in the study. Randomly chosen 36 patients receiving therapy constituted the study group, while the remaining 27 patients formed the control group and were followed without any treatment. The patients were questioned for symptoms and examined thoroughly at the beginning of the study and at the end of the third month. Thyroid function tests, lipid parameters and body mass index (BMI) were determined at both the beginning and the end of the study. Results: There were 32 (88.8%) female and 4 (11.2%) male patients in the study group; mean values of age and BMI were 44.66±13.34 years and 29.96±5.99 kg/m², respectively. The control group consisted of 23 (85.2%) female and 4 (14.8%) male patients; their mean values of age and BMI were 42.51±11.66 years and 30.68±5.61 kg/m², respectively. Mean TSH levels and mean fT3 levels were significantly decreased in the third month with respect to the beginning in patients receiving treatment when compared to the control group. In the beginning, the mean levels of serum LDL cholesterol were 127.55±44.69 mg/dl and 112.37±30.43 mg/dl in the study and control groups, respectively. Mean LDL cholesterol level showed a significant increase in the control group at three-month follow-up visit (p=0.041). Discussion: In this study, we found that the symptoms of clinical hypothyroidism mostly existed in patients with subclinical hypothyroidism, and clinical and metabolic parameters improved with levothyroxine therapy. (The Me di cal Bul le tin of Ha se ki 2011; 49: 131-6