Prolactin deficiency in pseudohypoparathyroidism.

Because thyrotropin deficiency may occur in pseudohypoparathyroidism, we studied pituitary function in two families with this condition. Six of eight patients had impaired pituitary prolactin secretion after administration of thyrotropin-releasing hormone and chlorpromazine, with preservation of other anterior pituitary functions. Peak serum prolactin levels after thyrotropin-releasing hormone and chlorpromazine in the prolactin-deficient patients were significantly lower than normal. Administration of diethylstilbestrol for five days, which normally enhances prolactin responses to thyrotropin-releasing hormone, had no effect on prolactin secretion in these patients. Although antilactotroph antibodies were not demonstrable, hypothyroidism or decreased thyroid reserve in four and antithyroid and antiparietal-cell antibodies in several family members suggest that an associated autoimmune process may be responsible for the prolactin deficiency.