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

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. 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. 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). Normal TSH level in patients with subclinical hyperthyroidism cannot commit the following euthyroidism in these patient.