Mild hyperthyroidism with inappropriate secretion of TSH in postmenopausal women.

In a previous study on the function of the hypothalamus - pituitary - thyroid axis, about 10% of postmenopausal women with the climacteric syndrome were found to have borderline high values of T3 and T4 and signs of pituitary decreased sensitivity to the suppressive effect of increased thyroid hormones. The present report concerns 5 women in the first phase of their menopause who showed a mild hyperthyroidism under basal conditions and after suppression test with liothyronine. Each patient had borderline increased levels of serum total and free T4 and T3 and a marked TSH responsiveness to exogenous TRH. After liothyronine, the serum levels of T4, FT4, TSH and the responsiveness to TRH-test clearly decreased. These data suggest an inappropriate TSH secretion with a decreased pituitary sensitivity to thyroid hormones. These cases could represent a modification of the hypothalamus-pituitary-thyroid axis associated with that of the gonadal axis, secondary to the absence of rapid adaptation of neurotransmitters.