Three cases of macroprolactinaemia.

A woman with hirsutism but otherwise symptom-free was found to have a raised serum prolactin and a pituitary microadenoma. The hyperprolactinaemia persisted despite bromocriptine therapy and subsequent pituitary surgery, which yielded a non-functioning adenoma. After a further 15 years with persistent hyperprolactinaemia but no symptoms, macroprolactinaemia was diagnosed. Such cases might account for part of the failure rate of pituitary microsurgery for prolactinoma. Testing for macroprolactinaemia is advisable in a woman with hyperprolactinaemia, especially if her ovulatory cycle is normal. Two other cases are reported in which macroprolactinaemia was associated with menstrual disturbances and other hormonal effects: in these, treatment with dopamine agonists suppressed the hyperprolactinaemia and restored normal menstrual cycles.