Prevalence and presentation of hyperprolactinaemia in patients with "functionless" pituitary tumours.

Serum-prolactin concentrations were measured in 111 patients who had radiological abnormalities of the pituitary but no evidence of acromegaly, Cushing's syndrome, or Nelson's syndrome. Raised prolactin levels were found in 45 of 64 (70%) patients studied before treatment and in 15 of 47 patients studied after pituitary surgery. The majority of hyperprolactinaemic patients presented with amenorrhoea or impotence; galactorrhoea was uncommon. By contrast, reproductive disorders were rare in patients with normal prolactin levels. It is concluded that pituitary tumours previously described as "functionless" are frequently associated with hypersecretion of prolactin and that such tumours usually present as reproductive disorders. In the investigation of patients with amenorrhoea or impotence serum-prolactin should be measured and skull radiology performed if the prolactin level is raised. Prolactin should be measured in all patients with abnormal pituitary X-rays both before and after pituitary surgery.