title: Evaluation of five immunoturbidimetric assays for urinary albumin quantification and their impact on albuminuria categorization.
abstract: OBJECTIVE
  The study was designed to evaluate the performance of five automated immunoturbidimetric assays to quantify urinary albumin, each corresponding to a combination of a reagent and an analyzer (Olympus on AU640, Roche on Cobas Integra, Abbott on Architect, Ortho-Clinical Diagnostics Vitros on Fusion and Siemens on Dimension).
  
  
  METHODS
  To assess imprecision, albumin was measured in three urinary pools with a mean value of 25, 66 and 131 mg/L. One hundred and eight patient urine samples were then used to compare each turbidimetric method using the Passing-Bablok regression and Bland-Altman analyses. Concordance of the albumin/creatinine ratio (ACR), according to the albuminuria classifications proposed by the KDIGO, was calculated to test the agreement between the different assays.
  
  
  RESULTS
  All immunoturbidimetric methods evaluated in this study exhibited acceptable imprecision (CV<6%). Mean values for 108 urine samples varied from 0.5 to 762.2 mg/L. Significant differences were found (p<0.05) between all methods except between Olympus and Ortho (p=1.0) and between Abbott and Roche (p=0.12). Regarding the albuminuria categories based on the ACR proposed by the KDIGO, only the classification obtained with the Roche method was significantly different from the four other methods (p<0.001).
  
  
  CONCLUSIONS
  We demonstrated that all assays were not strictly equivalent which could affect ACR categories in clinical practice, suggesting the need for harmonization of commercial methods.
authors: Laboratoire de Biochimie, CHRU Montpellier, Univ Montpellier 1, Montpellier F-34000, France.
authors: Anne-Sophie
authors: AS
authors: Bargnoux
authors: Laboratoire de Biochimie, CHRU Montpellier, Univ Montpellier 1, Montpellier F-34000, France.
authors: Amandine
authors: A
authors: Barrot
authors: Service de Médecine Interne, CHRU Montpellier, Univ Montpellier 1, Montpellier F-34000, France.
authors: Pierre
authors: P
authors: Fesler
authors: Laboratoire de Biochimie, CHRU Montpellier, Univ Montpellier 1, Montpellier F-34000, France.
authors: Nils
authors: N
authors: Kuster
authors: Laboratoire de Biochimie, CHRU Montpellier, Univ Montpellier 1, Montpellier F-34000, France.
authors: Stéphanie
authors: S
authors: Badiou
authors: Laboratoire de Biochimie, CHRU Montpellier, Univ Montpellier 1, Montpellier F-34000, France.
authors: Anne-Marie
authors: AM
authors: Dupuy
authors: Service de Médecine Interne, CHRU Montpellier, Univ Montpellier 1, Montpellier F-34000, France.
authors: Jean
authors: J
authors: Ribstein
authors: Laboratoire de Biochimie, CHRU Montpellier, Univ Montpellier 1, Montpellier F-34000, France. Electronic address: jp-cristol@chu-montpellier.fr.
authors: Jean-Paul
authors: JP
authors: Cristol
mesh_terms: D000418:Albumins / Q000032:analysis*; D000419:Albuminuria / Q000175:diagnosis* / Q000652:urine; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D009391:Nephelometry and Turbidimetry / Q000379:methods*; D012680:Sensitivity and Specificity
chemical_list: D000418:Albumins
keywords: Albumin/creatinine ratio (ACR); Evaluation; Immunoassay; Urinary albumin