| Abstract: | Studies of prolactin secretion in humans have confirmed the concept, derived originally from animal investigations, that prolactin is predominantly controlled by tonic inhibition from the hypothalamus. The locus of action of dopamine and dopaminergic agents such as the ergot alkaloids inhibiting prolactin secretion appears to be primarily at the pituitary level, though a hypothalamic action to increase secretion of prolactin inhibitory factor may also contribute. Prolactin hypersecretion, through any of several possible mechanisms, is frequently but not always found in patients with galactorrhea. Recent studies have shown that hyperprolactinemia is considerably more common than was previously appreciated among patients without galactorrhea. It is present in at least two-thirds of all patients with pituitary tumors and in a significant minority of patients with secondary amenorrhea. Its clinical measurement in these conditions is therefore of considerable diagnostic importance. Whatever the pathophysiology of its production, hyperprolactinemia of all forms is responsive to treatment with the newer ergot alkaloids. The potential use of these agents for therapeutic purposes, particularly in the treatment of infertility, appears to be wider than was originally anticipated. |
