title: Albuminuria, proteinuria, and novel urine biomarkers as predictors of long-term allograft outcomes in kidney transplant recipients.
abstract: BACKGROUND
  Proteinuria is an established marker of decreased kidney function after kidney transplant. It recently has been suggested that albuminuria might be a more reliable marker. Although albuminuria often is regarded as a marker of glomerular damage, because chronic renal allograft damage is believed to be predominantly an interstitial process, albuminuria in this case might reflect tubular damage. Accordingly, we investigated the value of albuminuria, proteinuria, and tubular damage markers (KIM-1 [kidney injury molecule 1], NAG [N-acetyl-β-d-glucosaminidase], NGAL [neutrophil gelatinase-associated lipocalin], and H-FABP [heart fatty acid binding protein]) in predicting graft outcome in kidney transplant recipients.
  
  
  METHODS
  Prospective observational cohort study.
  
  
  METHODS
  606 patients visiting our outpatient kidney transplant clinic in 2001-2003 were included and used in the analysis for death-censored graft failure. Median follow-up was 4.7 (25th-75th percentile, 3.8-5.2) years. 577 patients had follow-up longer than 1 year and were included in the analysis for estimated glomerular filtration rate (eGFR) decrease. Median follow-up was 3.2 (25th-75th percentile, 2.7-3.7) years.
  
  
  METHODS
  Urine protein, albumin, and tubular damage markers in 24-hour urine samples.
  
  
  RESULTS
  Death-censored graft failure and decrease in eGFR.
  
  
  RESULTS
  There were 42 patients with graft failure; mean eGFR change was -0.46 ± 3.7 (standard deviation) mL/min/1.73 m(2)/y. The area under the receiver operating characteristic curve for death-censored graft failure showed that albuminuria (0.78; 95% CI, 0.59-0.76) was significantly higher than proteinuria (0.67; 95% CI, 0.59-0.76; P = 0.001), NGAL (0.63; 95% CI, 0.52-0.74; P = 0.02), and H-FABP (0.62; 95% CI, 0.53-0.73; P = 0.005) and not significantly different from KIM-1 (0.74; 95% CI, 0.66-0.82) and NAG (0.75; 95% CI, 0.67-0.83). Results were similar for the eGFR decrease outcome.
  
  
  CONCLUSIONS
  Single-center observational study.
  
  
  CONCLUSIONS
  Measuring albuminuria may provide superior predictions for long-term renal outcomes after kidney transplant than total proteinuria. Additional assessment of urinary excretion of tubular damage markers may have limited value.
authors: Department of Internal Medicine, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.
authors: Ferdau L
authors: FL
authors: Nauta
authors: Stephan J L
authors: SJ
authors: Bakker
authors: Wim
authors: W
authors: van Oeveren
authors: Gerjan
authors: G
authors: Navis
authors: Jaap J Homan
authors: JJ
authors: van der Heide
authors: Harry
authors: H
authors: van Goor
authors: Paul E
authors: PE
authors: de Jong
authors: Ron T
authors: RT
authors: Gansevoort
mesh_terms: D000328:Adult; D000419:Albuminuria / Q000175:diagnosis / Q000276:immunology / Q000652:urine*; D015415:Biomarkers / Q000652:urine; D015331:Cohort Studies; D005260:Female; D006084:Graft Rejection / Q000175:diagnosis / Q000276:immunology / Q000652:urine*; D006801:Humans; D016030:Kidney Transplantation / Q000276:immunology / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011507:Proteinuria / Q000175:diagnosis / Q000276:immunology / Q000652:urine*; D013997:Time Factors; D014184:Transplantation, Homologous; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers