CONTRIBUTION TO THE PROBLEM OF HYPERPROLACTINEMIA - EXPERIENCE WITH 4,199 PROLACTIN ASSAYS AND 117 PROLACTINOMAS

Objective-To help define the normal and pathological serum prolactin c oncentration ranges in adult females. Patients and Methods-Serum prola ctin was assayed in a mixed population of 4,199 women divided into fiv e groups: (A) 753 with normal menses consulting for infertility (contr ol group); (B) 2,523 with menstrual disorders; (C) 519 with hirsutism and normal cycles; (D) 201 with galactorrhoea and normal cycles; (E) 2 03 with galactorrhoea and menstrual disorders. Results-In each group, a separate subset (2%, 3%, 1%, 15%, and 42.3%, respectively) was disti nguished, with scattered prolactin values above 30 ng/mL, in which 117 prolactinomas were found, with an incidence ranging from 11 to 57% in cases with prolactin of 31-49 ng/mL and from 65 to 87.5% in those wit h prolactin greater than or equal to 50 ng/mL. The frequency distribut ion of values from 1 to 30 ng/mL was strikingly similar in the 753 sub jects of group A and the 2,523 patients of group B: 91% and 92.6%, res pectively, between 1 and 15 ng/mL, and 5.5% and 4.7% from 16 to 20 ng/ mL. Values >20 ng/mL were found in 4.4% of the subjects in group A, 5. 5% in group B, 5.1% in group C, 21.8% in group D, and 18.7% in group E . Conclusions-(a) Normal prolactin values can be considered to include 1-15 ng/mL and 16-20 ng/mL, the former corresponding to the vast majo rity of normal subjects or patients, and the latter being the extreme limit of normal, for which from a clinical point of view repetition of the assay and a follow-up is advocated. (b) Values between 21 and 30 are rare and could be considered as hyperprolactinemia necessitating f urther investigation. (c) values between 31 and 49 are suspect, and va lues greater than or equal to 50 ng/mL are suggestive of the presence of a prolactinoma, warranting thorough investigation.