Placental proteins in male serum

Placental proteins such as human chorionic gonadotrophin (hCG), Schwangerschaftsprotein 1 (SP1) and pregnancy-associated plasma protein A (PAPP-A) are found in the blood of pregnant women and in subjects suffering from cancer. They can also be found in the blood of healthy non-pregnant women and in the seminal fluid of males. Surprisingly, hCG and SP1 could not be found in male serum, although PAPP-A occasionally occurs there.