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Comparison of Human Chorionic Gonadotropin Measurements by Radioimmunoassay and In Vitro Bioassay
Author(s) -
MADANES AMOS E.,
FENCL MONTSERRAT DE M.,
TULCHINSKY DAN
Publication year - 1985
Publication title -
american journal of reproductive immunology and microbiology
Language(s) - English
Resource type - Journals
eISSN - 1600-0897
pISSN - 8755-8920
DOI - 10.1111/j.1600-0897.1985.tb00275.x
Subject(s) - radioimmunoassay , bioassay , human chorionic gonadotropin , endocrinology , coefficient of variation , medicine , gonadotropin , chemistry , collagenase , testosterone (patch) , andrology , biology , chromatography , hormone , enzyme , biochemistry , genetics
A sensitive, accurate, and reproducible in vitro bioassay was developed for measuring human chorionic gonadotropin (hCG), based on testosterone production by collagenase‐dispersed interstitial cells of rat testes in response to hCG. The results were compared to those obtained by established beta hCG radioimmunoassay. The assay sensitivity was 25 pg hCG‐CR119/ml (65 μIU second IRP/ml). The intra‐assay coefficient of variation (CV) was 8.8%, and the interassay CV was 13% and 33% in the high and low ranges of the standard curve, respectively. hCG recoveries were 89.6 ± 3.12% (SE, n = 12). The pattern of serum bio‐hCG followed established patterns of immuno‐hCG, with the highest level measured during the first trimester (mean, 52,600 ± 7,250 SE (mIU/ml, n = 11), decreasing thereafter to a mean value of 7,400 ± 1,500 mIU/ml at term. The mean ratio of the bio/immunoactivity was consistently greater than one and did not significantly change at the various stages of pregnancy, or between normal and molar pregnancies (first trimester, 1.75 ± 0.12 SE; mid‐trimester, 1.46 ± 0.12; term, 1.50 ± 0.09; molar, 1.55 + 0.2). When serum bioactive and immunoactive hCG were measured in a woman at five weeks of pregnancy, an episodic secretion of hCG was obtained by both assays.