Secretion of Prolactin by Patients with Pituitary and Hypothalamic Tumors

Serum prolactin activity was determined by the 32P-casein in vitro bioassay in patients with various tumors of the pituitary and and hypothalamus. Markedly elevated values were observed in 9 patients with the Forbes-Albright syndrome, and the prolactin levels observed in these patients following removal of a chromophobe adenoma represented the relative effectiveness of the surgical resection. The rate of disappearance of prolactin from the serum after pituitary surgery indicated a biological half-life of approximately IS minutes for this hormone. Serum prolactin levels were also elevated in 4 patients who developed the Chiari-Frommel syndrome as a progressive manifestation of a chromophobe adenoma which appeared following bilateral adrenalectomy (Nelson's syndrome.) Serum prolactin activity was elevated in only one of 9 patients with acromegaly. Abnormal secretion of prolactin was a characteristic of 11 patients with various types of hypothalamic tumors. Increased secretion of prolactin was the only evidence of altered pituitary function in two of such patients, and prolactin secretion was the predominant pituitary function in two other patients who were found to have panhypopituitarism by other criteria. These studies indicate that the characterization of prolactin secretion may be of considerable value in the detection and management of patients with a wide variety of pituitary disorders.