[Molecular heterogeneity of hCG in urine of the patients with trophoblastic diseases]

Abstract

In addition to whole hCG, hCG beta-related molecular species are also present in the serum and urine of patients with trophoblastic diseases. We simultaneously measured whole hCG, free hCG beta and beta-core fragment in the serum and urine of patients with hydatidiform mole and choriocarcinoma by the highly specific and sensitive sandwich enzyme-immunoassay (EIA) systems using two kinds of antibodies. During the clinical courses of patients, although the whole hCG levels in serum and urine were closely correlated, the concentrations in the serum were almost twice as high as those in the urine. The free hCG beta levels were also closely correlated in serum and urine, but the concentrations of free hCG beta were extremely low as compared with those of whole hCG. Furthermore, free hCG beta/whole hCG ratios were significantly higher in choriocarcinoma patients than in hydatidiform mole patients. While whole hCG and free hCG beta were contained in both serum and urine, the beta-core fragment could be detected only in the urine of the patients. The relative contribution of the beta-core fragment to the total urinary hCG beta-immunoactivity accounted for about 40% in hydatidiform mole and about 70% in choriocarcinoma. We conclude that whole hCG should be measured in the serum rather than in the urine as a tumor marker for trophoblastic diseases, and suggest that the ratios of whole hCG, free hCG beta and beta-core fragment to each other may be useful indices to employ in the differential diagnosis of trophoblastic diseases.