Serum prolactin in patients with hypothalamus and pituitary disorders
✓ Serum prolactin concentrations were studied in 115 patients with anatomically defined disorders in the hypothalamo-pituitary region. Fifty of the patients had expansively growing pituitary adenomas; in 17 of them (13 females and four males) the prolactin values were slightly raised (15 to 100 µg/liter), and in 13 (11 females and two males) they were over 100 µg/liter. The frequency of elevated prolactin values was higher for females than for males. Fifteen patients with invasively growing pituitary adenomas had very high serum prolactin levels (range 1230 to 31,500 µg/liter, geometric mean 3150 µg/liter). In a single case of malignant pituitary adenoma, the serum prolactin was at the lower level of detection. Of 49 further patients with suprasellar meningiomas, craniopharyngiomas, or other expansive or destructive lesions of the hypothalamus and sellar region, 15 had slightly raised prolactin values (maximum 114 µg/liter). Eight of these 49 patients had sellar destruction, with a roentgenological picture similar to that in patients with invasive pituitary adenomas. Among these eight patients, the maximum prolactin value was 67 µg/liter. It is concluded that moderately raised serum prolactin values (up to 100 µg/liter) in a patient with a sellar tumor does not prove that the tumor is a prolactinoma. A serum prolactin value of 100 to 1000 µg/liter strongly indicates a prolactin-producing tumor. In a patient with sellar destruction, a serum prolactin value of over 1000 µg/liter is proof that the destruction is caused by an invasive pituitary adenoma.