Thyroid hormones in benign breast disease. Normalization of exaggerated prolactin responsiveness to thyrotropin-releasing hormone.

To investigate the exaggerated prolactin (PRL) responsiveness to thyrotropin-releasing hormone (TRH) in patients with benign breast disease (BBD), 18 patients and 13 healthy controls underwent an 8-week-long thyroid hormone treatment. The clinical effect of thyroid hormones on cyclical mastodynia and concomitant galactorrhea was evaluated. TRH-stimulated PRL and thyroid-stimulating hormone (TSH) responses and thyroxine, triiodothyronine, thyroxine-binding globulin, as well as serum estradiol and progesterone levels, were measured before and during hormone treatment. Thirteen of the patients and one of the controls had euthyroid diffuse goiter. Patients and controls had normal thyroid function parameters. During thyroid hormone treatment, significantly elevated TRH-induced PRL responses of the patients decreased by 50% and reached levels of the controls, whereas responses of the controls decreased insignificantly. Patients exhibited significantly lower serum progesterone levels than the controls; the estradiol levels were not different. Thyroid hormone treatment had no significant influence on luteal function of patients or controls. In 16 of 18 patients thyroid hormones were of benefit to mastodynia, whereas galactorrhea remained unaffected.