Immunoassays for low concentrations of albumin in urine.
We have developed and validated simple, rapid immunoassays to measure concentrations of albumin in urine ranging from 5 to 200 mg/L. We use antiserum to human albumin, raised in sheep, and we separate the antibody-bound and free fractions of albumin by using a second antiserum, produced in donkeys, against the Fc fragment of sheep IgG. These two antisera can be mixed and added to assay tubes as a single reagent without inhibiting antigen binding. Samples or standards are incubated for at least 30 min with fluorescein-labeled albumin and the premixed antiserum reagent. After brief centrifugation, the supernate is discarded and the precipitate containing the bound fraction is dissolved and its fluorescence measured. Alternatively, 125I-labeled albumin can be used as tracer with all other reagents unchanged; in this case one simply counts the radioactivity of the bound fraction. A reference interval of less than 0.2-2.8 mg/mmol of creatinine was obtained for untimed, daytime, midstream urine specimens from 80 healthy subjects.
D000293:Adolescent; D000328:Adult; D000368:Aged; D000418:Albumins / Q000032:analysis* / Q000276:immunology; D003928:Diabetic Nephropathies / Q000652:urine*; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007106:Immune Sera; D007202:Indicators and Reagents; D008297:Male; D008875:Middle Aged; D011863:Radioimmunoassay / Q000379:methods; D012016:Reference Values; D013048:Specimen Handling
D000418:Albumins; D007106:Immune Sera; D007202:Indicators and Reagents