[Prolactin, bromocriptine and gonadic function in women: recent discoveries. I. The physiology of prolactin and the physiopathology and diagnosis of hyperprolactinaemias].

Estrogens are involved in the regulation of the secretion and release of prolactin, and so are a large number of neurotransmitters and neuropeptides. This explains why the circulating level of prolactin is very labile. Most of these elements work by bringing about small changes in the tone of the dopaminergic inhibitor system, which is the principal controlling factor for this hormone. Most hyperprolactinaemias of a pathological nature seem to be the result of a failure of this dopaminergic inhibiting system. Prolactin has a rudimentary luteotrophic function, but it does act as an inhibitor of female gonadic function as soon as the circulating level reaches about 30 ng/ml, and it exerts its effects at two levels--the ovarian and the hypothalamic. Estimating levels of prolactin should be carried out according to a strict protocol so that many causes of non-pathological rise can be excluded. Hyperprolactinaemia should be sought whenever anovulation is found whether it is accompanied by galactorrhoea or not. Certain cases of hyperprolactinaemia are secondary to different types of aetiology which have to be searched for. When confronted with a case of primary hyperprolactinaemia the search should be towards diagnosis of a pituitary adenoma, which is often present although very small. Two examinations that are of most value to diagnose this condition are standard X-rays of the pituitary fossa and scanning tomography.