Effect of different hormonal therapies on thyroid function in surgical menopause: short-term results.

To determine the effects of different hormone replacement therapy (HRT) regimens on thyroid function in surgical menopause.In a randomized, controlled study, 59 euthyroid women with surgical menopause were randomized to an estrogen-only (n=20), tibolone (n=20) or calcium-only (n=19) group. On the 5th postoperative day and 4th and 12th weeks, serum E2, TSH, free T3 and free T4 levels were determined.Although the initial and week 4 serum E2, TSH, free T3 and free T4 levels were comparable, the week 12 serum E2 and TSH levels were different between the subjects on estrogen therapy and those receiving tibolone or calcium only (p=0.008 and 0.000, respectively). Serum E2 levels were higher and TSH levels lower in subjects receiving estrogen. Moreover, serum TSH levels correlated negatively with serum E2 levels in the 12th week of estrogen use (r=-0.354, p=0.006). TSH increased in the tibolone group as compared to the estrogen group but was still lower than in the calcium-only group; however, the differences were not statistically significant.Irrespective of different regimens, HRT does not have an important short-term effect on thyroid function in women with surgical menopause.