title: Evaluation of a new fluorescent dye method to measure urinary albumin in lieu of urinary total protein.
abstract: Urinary total protein (UTP) determinations are notoriously inaccurate, poorly reproducible, and difficult to interpret in early renal disease, causing many investigators to measure urinary albumin instead. In this study, we compare a new nonimmunologic fluorescent dye (AB-dye) for measuring albumin with the more expensive and cumbersome radioimmunoassay. We tested 207 urine specimens from patients with variable protein concentrations and divided the results into five arbitrary ranges (0 to 20, 21 to 50, 51 to 100, 101 to 200, and 201 to 400) for chi-square analysis. There was a high degree of correlation between the two methods (chi-square = 260. 8 with 16 degrees of freedom; P < 0.001). The correlation was also high when analyzed by linear regression (R = 0.86; F < 0.01). Based on our comparison of total protein and albumin concentration in the same urine samples, we hypothesized that patients with mild proteinuria may not necessarily have microalbuminuria. Urine samples with UTP between 150 and 400 microg/mL were tested for albumin by the AB-dye. Of 41 samples in this range, 18 (44%) had normal albumin levels. We conclude that measuring urinary albumin with the AB-dye is comparable in performance to radioimmunoassay and could replace UTP determinations, especially for patients with borderline elevations of UTP, many of whom do not have microalbuminuria.
authors.affiliation: Divisions of Nephrology at Cook County Hospital, the University of Illinois College of Medicine, the Chicago VA Health Care System, and the Hektoen Institute for Medical Research, Chicago, IL 60612, USA.
authors.forename: A A
authors.initials: AA
authors.lastname: Pegoraro
authors.forename: W
authors.initials: W
authors.lastname: Peracha
authors.forename: M
authors.initials: M
authors.lastname: Hasnain
authors.forename: N
authors.initials: N
authors.lastname: Ranginwala
authors.forename: M
authors.initials: M
authors.lastname: Shaykh
authors.forename: A K
authors.initials: AK
authors.lastname: Singh
authors.forename: J A
authors.initials: JA
authors.lastname: Arruda
authors.forename: G
authors.initials: G
authors.lastname: Dunea
mesh_terms: D000419:Albuminuria / Q000652:urine*; D005456:Fluorescent Dyes; D006801:Humans; D009570:Nitriles; D011507:Proteinuria / Q000652:urine*; D011863:Radioimmunoassay; D012044:Regression Analysis
chemical_list: C106561:Albumin Blue 580; D005456:Fluorescent Dyes; D009570:Nitriles