Hyperprolactinaemia in amenorrhoea - incidence and clinical significance.
Prolactin concentrations in serum were determined in 287 women with amenorrhoea. The incidence of hyperprolactinaemia was 14.6 per cent. All but 4 of the 31 women with persistent hyperprolactinaemia had galactorrhoea. Radiological signs suggestive of a pituitary tumour were seen in 48 per cent of the hyperprolactinaemic women, while only 4.5 per cent of the 245 normoprolactinaemic women had abnormal sellar X-rays. All the patients with prolactin concentrations above 100 microgram/1 had radiologically abnormal sellae, but lower prolactin levels did not rule out the existence of even large pituitary tumours. The hyperprolactinaemic women with normal and abnormal sellae and a control group of healthy women in the early follicular phase all had similar mean basal FSH and LH levels with one exception, the group with abnormal sellae had lower basal LH levels than the control group. There was no difference in the mean FSH and LH responses to LH-RH between the hyperprolactinaemic women with pathological sellae and the control group while the hyperprolactinaemic women with normal sellae had higher responses than the other two groups. Prolactin determinations were found to be superior to other pituitary hormone estimations for identifying patients who are at risk of having pituitary tumours.