Prolactin-secreting pituitary adenomas in multiple endocrine adenomatosis, type I.

In three unrelated families, four patients with multiple endocrine adenomatosis, type I, had confirmed or highly probable prolactin-secreting pituitary adenomas. In one patient, selective transsphenoidal tumor resection resulted in normal prolactin levels and resumption of menses. Heretofore, the majority of pituitary tumors in such patients had been thought to be nonsecreting chromophobe adenomas, but recent studies have shown that, in sporadic cases, as many as three fourths of "nonsecreting" pituitary tumors in fact secrete prolactin. Thus, based on our experience and reports of others, we believe that prolactin-secreting tumors may be common in patients with pituitary tumors as part of the syndrome of multiple endocrine adenomatosis, type I, and we recommend that serum prolactin be measured when evaluating these patients and their families.