Urine high and low molecular weight proteins one-year post-kidney transplant: relationship to histology and graft survival

Am J Transplant. 2013 Mar;13(3):676-84. doi: 10.1111/ajt.12044. Epub 2013 Feb 15.


Increased urinary protein excretion is common after renal transplantation and portends worse outcome. In this study we assessed the prognostic contribution of several urinary proteins. Urinary total protein, albumin, retinol binding protein (RBP), α-1-microglobulin, IgG and IgM were measured in banked urine samples from 221 individuals 1 year after renal transplantation (age 52 ± 13 years, 55% male, 93% Caucasian and 82% living donor). Levels of all proteins measured were higher than in normal nontransplant populations. Patients with glomerular lesions had higher urinary albumin than those with normal histology, while those with interstitial fibrosis and tubular atrophy plus inflammation (ci>0, cg = 0, i>0) had higher levels of IgG, IgM, α-1-microglobulin and RBP. Concomitant normal levels of urinary albumin, IgM and RBP identified normal histology (specificity 91%, sensitivity 15%,). Urinary levels of the specific proteins were highly correlated, could not differentiate among the histologic groups, and appeared to result from tubulointerstitial damage. Increased urinary excretion of the low molecular weight protein RBP was a sensitive marker of allografts at risk, predicting long-term graft loss independent of histology and urinary albumin. This study highlights the prognostic importance of tubulointerstitial disease for long-term graft loss.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Albuminuria
  • Alpha-Globulins / urine
  • Biomarkers / urine*
  • Creatinine / urine
  • Female
  • Graft Rejection / diagnosis*
  • Graft Rejection / urine
  • Graft Survival / physiology*
  • Humans
  • Immunoglobulin G / urine
  • Immunoglobulin M / urine
  • Kidney Diseases / pathology
  • Kidney Diseases / therapy
  • Kidney Diseases / urine*
  • Kidney Transplantation*
  • Male
  • Middle Aged
  • Molecular Weight
  • Prognosis
  • Proteinuria
  • Retinol-Binding Proteins, Cellular / urine
  • beta 2-Microglobulin / urine


  • Alpha-Globulins
  • Biomarkers
  • Immunoglobulin G
  • Immunoglobulin M
  • Retinol-Binding Proteins, Cellular
  • alpha-1-microglobulin
  • beta 2-Microglobulin
  • Creatinine