Prolactin in seminal fluid.

Prolactin appears to modulate male reproduction by regulating hormone receptor levels in the testis and accessory sex organs and by facilitating spermatozoal biochemical processes associated with capacitation. A large portion of immunoreactive prolactin (iPRL) seems to be transported from blood to semen via the accessory sex organs and takes several days to make this transition. The iPRL in semen is heterogeneous in size and a unique portion may be associated with spermatozoa. Data from several clinical studies of seminal fluid prolactin are inconsistent. The variability of patient populations classified as fertile or infertile, the differences in prolactin assays used, and the lack of information about sample processing have been major causes of this difficulty.