title: Specificity of human beta-choriogonadotropin assays for the hormone and for an immunoreactive fragment present in urine during normal pregnancy.
abstract: We evaluated four high-purity commercial preparations of human choriogonadotropin (hCG; Boehringer-Mannheim, Calbiochem, Cambridge, and Radioassay Systems) by two radioimmunoassays and one radioreceptor procedure. Their specific activities were less than half that of the first International Reference Preparation of hCG for immunoassay. In addition, a fragment that was immunoreactive in radioimmunoassays for hCG with antisera to the beta-subunit conformational determinant was isolated from crude hCG (Roussel Corp.). The fragment adsorbed to concanavalin A and exhibited a relative molecular mass of 12 000 by gel filtration. In a study with 94 urines from women three to 24 weeks pregnant, the fragment contributed more than 70% of the immunoreactivity detected by the above radioimmunoassays for hCG in 70% of the samples. The fragment was present in urine throughout pregnancy, but was not detected in the serum of any of seven pregnant women tested.
mesh_terms: D006063:Chorionic Gonadotropin / Q000032:analysis* / Q000276:immunology / Q000652:urine; D002850:Chromatography, Gel; D003429:Cross Reactions; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D011247:Pregnancy; D011863:Radioimmunoassay; D011869:Radioligand Assay
chemical_list: D006063:Chorionic Gonadotropin