Pregnancy-associated plasma protein A (PAPP-A) in non-pregnant subjects.

A newly developed enzyme immunoassay technique was applied to the measurement of pregnancy-associated plasma protein A (PAPP-A) in the serum of women in the proliferative and luteal phases of the cycle, in hysterectomized and postmenopausal women and in the serum and seminal plasma of males. PAPP-A was detected in some individuals in all the categories of women and in seminal plasma but not in male serum. It is surmised that there must be a source of PAPP-A other than the placenta and that PAPP-A may be a maternal protein whose biosynthesis is stimulated by pregnancy rather than a product peculiar to the trophoblast.