The results of six months follow up in patients with subclinical thyrotoxicosis

Introduction: There is no definite treatment for subclinical hyperthyroidism which is defined as suppressed TSH and normal T3 and T4 levels. In this study, patients with subclinical hyperthyroidism were followed for 6 months without any medical treatment. Methods: A total number of 285 patients of individuals who participated in Tehran glucose and lipid study and had TSH≤0.3 mu/l and normal T3, T4 levels were included. Second TSH measurement followed by a classic TRH measurement was done in these subjects. Finally 20 subjects were included in the study according to inclusion criteria (TSH≤0.3 mu/L and TSH rising lower than 1 mu/L after TRH test). These subjects were followed for 6 months and hormone measurements were performed at first, second and sixth months. Results: The mean±SD of patients age was 48±13 years and 12 patients were female. The mean of TSH level was 0.2±0.1 mu/l at presentation and T3 and T4 concentration were in normal range. A significant increase in mean of TSH level was seen at first and second months (0.7±0.1 and 0.6±0.2 mu/l respectively p<0.01) as compared with the basic levels. The mean of TSH level was suppressed again in sixth month (0.3±0.5 mu/L). Conclusion: Normal TSH level in patients with subclinical hyperthyroidism cannot commit the following euthyroidism in these patient.