Observations on immunochemical assays of human chorionic gonadotropin.

Commercial immunochemical tests, "UCG" and "Prepuerin", detected standardized human chorionic gonadotropin (HCG) in concentrations comparable to the rat ovarian hyperemia test. These in vitro systems also cross-reacted with pituitary luteinizing hormone (LH) but not with follicle-stimulating hormone (FSH) of animal origin. The latex agglutination slide tests required a higher concentration of HCG for a positive test than did the bioassay. In cases of abnormal pregnancies the immunochemical assays remained positive longer than the bioassay, which is apparently due to their detection of biologically inactive HCG. Several non-pregnant patients with ovarian cysts and cystic teratomas excreted in their urine some substances which reacted with the UCG test. After surgical removal of the tumour these substances disappeared from the urine.