Evaluation and clinical application of the quantitative radioreceptor assay for serum hCG

An evaluation of a radioreceptor assay (RRA) for the quantitation of human chorionic gonadotropin (hCG) in serum resulted in intra- and interassay variations of 2.6 and 5.5% (average), respectively. Recovery of hCG in a preparation of second IRP-hCG gave an accuracy of 93.2%. Standard curve data demonstrated that variation in reagent addition and incubation time allowed for flexibility in the use of the assay depending on the level of sensitivity desired. The most sensitive assay, which used an incubation of 2 hours, gave a usable range of 40--250 mIU/ml hCG on the standard curve. The applicability of the quantitative RRA in clinical cases is shown with 9 patients (total of 31 serum samples) in a comparison study with a radioimmunoassay (RIA) for the beta-subunit of hCG.