title: A sensitive quantitative test strip based point-of-care albuminuria screening assay.
abstract: BACKGROUND
  Chronic kidney disease is a major health problem and the global guidelines require screening of albuminuria. Therefore, affordable and sensitive albuminuria screening tests are needed. We explored the potential of urine strips, generally reported in the ordinal scale, measured on an automatic strip reader for reporting quantitative and sensitive albumin results.
  
  
  METHODS
  We compared reflectance data of Combur-Test® strips obtained from the Cobas U411 reader (Roche) with albuminuria data from a nephelometer BNII (Siemens) and with protein concentrations from the pyrogallol red method (Modular P, Roche) for 389/328 non-pathologic and pathologic urine samples, respectively.
  
  
  RESULTS
  Imprecision of the reflectance signal of the Cobas U411 was measured with commercial control material (Bio-Rad). Inter-run coefficients of variations (CVs) for reflectance for levels 1 and 2 were 1.7%/4.9%, respectively, and intra-run CVs were 1.8%/4.2%, respectively. Good agreement was obtained between the albumin concentration of the BNII and the protein strip reflectance data (n=389): Y (10,000/protein reflectance, 1/%)=160+0.132·X (albuminuria BNII, mg/L)-0.0000111·X2 (albuminuria BNII, mg/L); r2=0.921. Lower agreement was found between the protein assay (n=328) and the reflectance (r2=0.831). A calibration curve was made between 11.5 mg/L and 121.5 mg/L. The limit of blank (LOB) was 44.7 mg/L.
  
  
  CONCLUSIONS
  The present study demonstrates that reflectance data generated by a test strip reader allows for quantitative analysis of albumin. Although the lower limit of the microalbumin range (30 mg/L) cannot be achieved with the dye-binding method, the results are satisfactory for screening purposes.
authors.affiliation: Department of Clinical Chemistry, Ghent University Hospital, Ghent, Belgium.
authors.forename: An-Sofie C
authors.initials: AS
authors.lastname: Decavele
authors.forename: Tom
authors.initials: T
authors.lastname: Fiers
authors.forename: Joris
authors.initials: J
authors.lastname: Penders
authors.forename: Joris R
authors.initials: JR
authors.lastname: Delanghe
mesh_terms: D000328:Adult; D000419:Albuminuria / Q000175:diagnosis* / Q000652:urine; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008875:Middle Aged; D009391:Nephelometry and Turbidimetry; D019095:Point-of-Care Systems / Q000592:standards; D011507:Proteinuria / Q000175:diagnosis / Q000652:urine; D011934:Reagent Strips / Q000737:chemistry*; D012016:Reference Values; D055815:Young Adult
chemical_list: D011934:Reagent Strips