Urine High and Low Molecular Weight Proteins One-Year Post-Kidney Transplant: Relationship to Histology and Graft Survival

Authors

  • H. Amer,

    Corresponding author
    1. The William J von Liebig Transplant Center, Mayo Clinic, Rochester, MN
    • Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN
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  • J. C. Lieske,

    1. Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN
    2. Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN
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  • A. D. Rule,

    1. Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN
    2. Division of Epidemiology, Mayo Clinic, Rochester, MN
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  • W. K. Kremers,

    1. The William J von Liebig Transplant Center, Mayo Clinic, Rochester, MN
    2. Department of Health Sciences Research, Mayo Clinic, Rochester, MN
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  • T. S. Larson,

    1. Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN
    2. Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN
    3. Division of Transplant Surgery, Mayo Clinic, Rochester, MN
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  • C. R. Franco Palacios,

    1. Clinical Fellow, Mayo School of Graduate Medical Education, Mayo Clinic, Rochester, MN
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  • M. D. Stegall,

    1. The William J von Liebig Transplant Center, Mayo Clinic, Rochester, MN
    2. Division of Transplant Surgery, Mayo Clinic, Rochester, MN
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  • F. G. Cosio

    1. Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN
    2. The William J von Liebig Transplant Center, Mayo Clinic, Rochester, MN
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Corresponding author: Hatem Amer

amer.hatem@mayo.edu

Abstract

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.

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