[Studies on the heterogeneity of urinary HCG molecules by RRA and RIA (author's transl)].

A sensitive bioassay (Radio receptor assay: RRA) for urinary hCG which is independent of plasma half life and metabolism has been developed by utilizing the specific binding of 125I-hCG to 150 approximately 2000g fraction of homogenates of the rat testis. The receptor and immunological activity (RRA/RIA) ratio of urinary hCG in pregnant and trophoblastic diseased women was examined. In addition, the urine of women with normal pregnancies was studied for quantitative and qualitative differences among hCG molecules, by gel filtration on a Sephadex G-100, and each fraction was measured by RRA and radioimmunoassay (RIA). 1) The sensitivity of RRA was 4 ng/ml with a precision (lambda) of 0.03. The intraassay coefficient of variation and that for inter assay were 2 approximately 10% and 12.1% respectively. There was a complete lack of cross reaction with PRL, hCG alpha, hCG beta, and FSH; this indicated a high specificity of the RRA. 2) Receptor reactive hCG in urine throughout pregnancy showed a major peak in the 10th week and declined, but remained fairly constant until the 31st week of pregnancy. The RRA/RIA ratio in urinary hCG of normal pregnancies was highest in the first trimester and lower in the second and third trimester. The average value throughout gestation was 2.04 +/- 0.18 (SE), which was about 2 times greater than that (1.08 +/0 0.11(SE)) of trophoblastic diseases (p less than 0.01). 3) The RRA/RIA ratio in the patients with trophoblastic tumors was highest in the hydatidiform mole and lowest in the chorioepithelioma. 4) When the urine of normal pregnancies was gel filtrated on a Sephadex G-100, it was found that receptor active molecules of hCG were present in urine of the first and second trimester. These results indicated that the RRA/RIA ratio in urinary hCG was distinct in normal pregnancies from trophoblastic tumors and would contribute sufficiently to an early diagnosis and the treatment of successive trophoblastic disease in follow-ups of patients with hydatidiform mole.