The epidemiology of hyperprolactinaemia over 20 years in the Tayside region of Scotland: the Prolactin Epidemiology, Audit and Research Study (PROLEARS).

Objective: To estimate the prevalence and incidence of hyperprolactinaemia. Hyperprolactinaemia is a common problem in endocrine practice, but its epidemiology has not been accurately established.

Study Design: A population-based retrospective follow-up study in Tayside, Scotland (population 400,000), from 1993 to 2013.

Patients: Record linkage technology (biochemistry, prescribing, hospital admissions, radiology, mortality and maternity data) was used to identify all patients with a serum prolactin measurement. From these, cases were defined as those with a prolactin greater than 1000 mU/L (47·2 ng/ml) or at least three prescriptions for a dopamine agonist.

Measurements: Number of prevalent and incident cases of hyperprolactinaemia per calendar year by age, sex and cause of hyperprolactinaemia.

Results: A total of 32289 patients had a serum prolactin assay undertaken, of which 1301 had hyperprolactinaemia not related to pregnancy: 25·6% patients had pituitary disorder, 45·9% were drug-induced, 7·5% had macroprolactin and 6·1% had hypothyroidism, leaving 15·0% idiopathic. Over the 20 years, there was a fourfold increase in the number of prolactin assays performed, and prevalence of hyperprolactinaemia was initially 0·02%, but rose to 0·23% by 2013. Overall incidence was 13·8 cases per 100000 person-years (20·6 in 2008-13) and was 3·5 times higher in women than in men. The highest rates were found in women aged 25-44 years. Drug-induced causes tripled during the 20 years.

Conclusions: Rising prevalence of hyperprolactinaemia is probably due to an increased ascertainment and increased incidence of psychoactive drug-related causes. Rates are higher in women than in men but only before the age of 65 years.