Circulating prolactin levels. I. Normal females.

A specific, homologous radioimmunoassay was used to quantitate circulating levels of prolactin in females in various stages of life. They were grouped in periods of newborns to peripubertal females, reproductive, gravid and puerperal, and postmenopausal females. The results reveal dynamic changes of prolactin throughout various stages of life and support the mounting evidence that prolactin's role in humans might mimic that of animals. The role of prolactin in the ovarian cycle is unclear and will have to be ascertained at the molecular level.