Primary hypothyroidism and galactorrhea.

Ten of 16 women with primary hypothyroidism and high thyrotropin (TSH) concentrations had high serum prolactin (PRL) concentrations. A positive correlation was observed between the basal TSH and PRL levels in the hypothyroid patients. Five of these patients complained of persistent galactorrhea after delivery. After treatment with triiodothyronine (T3), the elevated TSH and PRL levels fell to within normal ranges, and the galactorrhea disappeared. It is suggested that the elevated serum PRL levels of patients with primary hypothyroidism are mediated by feedback-induced thyrotropin-releasing hormone (TRH) secretion or an enhanced response to endogenous TRH, and that the combination of delivery and the PRL excess may induce persistent galactorrhea in patients with primary hypothyroidism.