Clinical history and outcome of 59 patients with idiopathic hyperprolactinemia.

Objective: To investigate the clinical course of hyperprolactinemia without demonstrable cause.

Design: Prospective study of all patients with idiopathic hyperprolactinemia first seen between 1974 and 1985.

Setting: Outpatient Department of University Hospital.

Patients: Fifty-nine patients followed for 6 to 190 months (median 78 months). Medical treatment given only in case of anovulatory infertility or hypogonadism.

Outcome Measures: Development of pituitary (micro)prolactinoma, prolactin (PRL) levels, and clinical signs of menstrual dysfunction.

Results: With exception of one woman in whom it probably had been missed by hypocycloidal tomography, no demonstrable prolactinoma developed. Prolactin levels rose in two patients, one using oral contraceptives and the other with prolactinoma. At the end of follow-up, 15 of 16 patients using a dopaminergic drug had a normal cycle; 13 had normal final PRL levels. From the 43 patients off medication, 28 (66%) had normal PRL levels and 23 (54%) had a normal cycle. There were no significant differences between women who had and had not been pregnant. Dopaminergic medication had no appreciable influence on the course of the disease.

Conclusion: In idiopathic hyperprolactinemia, progression to pituitary prolactinoma seldom, if ever, occurs. There is a high tendency to spontaneous cure, and pregnancy or medication have no apparent effect. Frequent pituitary imaging was found to be not necessary in our patient population. It may best be reserved for situations in which the PRL level in symptomatic hyperprolactinemia is inconsistent with pituitary imaging results.