title: Effect of variations in globulin concentrations on serum radioimmunoassay results, as exemplified by choriogonadotropin.
abstract: Variations in serum protein concentrations can affect results of radioimmunoassay of human choriogonadotropin involving either polyethylene glycol or double-antibody methods of separation. Relative to the maximal binding of choriogonadotropin in the presence of normal (30 g/L) globulin concentrations, globulin concentrations of 10 to 60 g/L were associated with maximal binding ranging from 84.9 to 115.6% in the polyethylene glycol system, and from 109.9 to 92.5% in the double-antibody system. This effect was quantitatively much the same throughout the standard curve in the polyethylene glycol system, but diminished with the higher standard concentrations in the double-antibody system. In assays involving polyethylene glycol separation, an increase in globulin was associated with a linear increase in nonspecific binding, but no detectable effect of globulin on nonspecific binding was observed in the double-antibody system. Determination and compensation for nonspecific binding of individual samples (rather than for mean assay nonspecific binding) eliminated the globulin effect in the polyethylene glycol system but not in the double-antibody system.
mesh_terms: D006063:Chorionic Gonadotropin / Q000097:blood*; D018997:Chorionic Gonadotropin, beta Subunit, Human; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D010446:Peptide Fragments / Q000097:blood*; D011092:Polyethylene Glycols; D011247:Pregnancy; D011863:Radioimmunoassay / Q000379:methods; D012709:Serum Albumin / Q000032:analysis; D012712:Serum Globulins / Q000032:analysis*; D014328:Trophoblastic Neoplasms / Q000097:blood*; D014594:Uterine Neoplasms / Q000097:blood*
chemical_list: D006063:Chorionic Gonadotropin; D018997:Chorionic Gonadotropin, beta Subunit, Human; D010446:Peptide Fragments; D012709:Serum Albumin; D012712:Serum Globulins; D011092:Polyethylene Glycols