October 11, 1976

Prolactin Production by Pituitary Adenomas

Author Affiliations

University of Toronto

JAMA. 1976;236(15):1692-1693. doi:10.1001/jama.1976.03270160016014

To the Editor.—  In the article "Hyperprolactinemia associated with empty sella syndrome" (235:2002, 1976), Dr Hsu and associates reported a case of a 37-year-old woman with high serum prolactin levels (475μg/ml). However, subsequent surgical intervention failed to show a pituitary tumor, although this diagnosis was reasonably assured preoperatively.This case clearly shows the difficulties encountered when one intends to diagnose pituitary tumors in general and prolactin-producing adenomas in particular based on serum prolactin measurements. Hyperprolactinemia can be due not only to prolactin-secreting adenoma but also to other abnormalities that compress the hypophysial stalk or hypothalamus and interfere with the production, release, or adenohypophysial transport of hypothalamic regulatory substances, thus causing increased discharge of prolactin from the nontumorous pituitary. Recent evidence indicates that immunocytology and electron microscopy permit the separation of prolactin-producing pituitary adenomas from those not consisting of prolactin cells.1,2 The purpose of our letter is to stress the