Hyperprolactinaemia: its physiology and investigation.

Since the establishment of a sensitive and specific radioimmunoassay for serum prolactin levels, very rapid progress has been made in the understanding of the physiology of prolactin and its role in human disease. Hyperprolactinaemia is now known to be a common finding in many conditions. Up to 20% of women with unexplained functional secondary amenorrhoea have an elevated serum prolactin level. Reduction of serum prolactin levels to normal, by removal of a prolactin-secreting tumour or by treatment with bromoergocryptine, results in a restoration of normal menstrual cycles and fertility. This paper outlines the control of prolactin secretion and discusses the mechanisms which result in secondary amenorrhoea. A new method of investigation of hyperprolactinaemia is proposed which localizes the site of abnormality which results in an elevation of serum prolactin levels.