Prolactin in clinical practice

ISOLATION of human prolactin and the development of highly sensitive and specific radioimmunoassays have allowed precise quantitation of serum prolactin concentrations in humans. Although changes in prolactin secretion have been described in a variety of physiologic and pathologic conditions, our understanding of the physiologic effects of prolactin is scant. Only the obligatory role of prolactin in lactation has been established. Since random serum prolactin concentrations are only slightly lower in normal men than in normal women, prolactin may have physiologic effects unrelated to lactation. The kidney¹and the adrenal²have been suggested as target organs for prolactin action. Further investigative efforts are required to explore the implications of these and other possible physiologic effects of prolactin in man.

Regulation of Prolactin Secretion

Prolactin-Inhibitory Factor (PIF).—

Prolactin secretion is primarily under tonic hypothalamic inhibitory control (Figure). Although a specific PIF has yet to be isolated, the importance of this