HYPERPROLACTINEMIA: GALACTORRHEA-AMENORRHEA SYNDROME - Etiology



Prolactin is under chronic inhibitory control by a hypothalamic factor (presumably dopamine). Any pharmacologic agent or lesion of the hypo­thalamus or pituitary stalk that interferes with do­pamine secretion or its action can result in hy-perprolactinemia. In view of the wide clinical use of pharmacologic agents that interfere with do­paminergic transmission, such as the phenothia-zines, it is not surprising that the majority of patients with hyperprolactinemia do not har­bor a pituitary adenoma. Once the use of such an agent can be excluded, however, and mechani­cal or neurogenic factors eliminated, the frequency with which a pituitary microadenoma is found is quite high. The most common pituitary tumor, chromophobe adenoma, once thought to be nonfunctioning and endocrinologically silent, is frequently a prolactin-secreting adenoma (pro­lactinoma).