Table of Contents
Journal of Biomarkers
Volume 2014, Article ID 492838, 7 pages
http://dx.doi.org/10.1155/2014/492838
Research Article

Urinary β2-Microglobulin Is a Good Indicator of Proximal Tubule Injury: A Correlative Study with Renal Biopsies

1Department of Pathology and Laboratory Medicine, Temple University Hospital, 3401 North Broad Street, Room A2-F326, 2PAP, Philadelphia, PA 19140, USA
2Bostwick Laboratories, Orlando, FL 32809, USA
3Department of Pathology, Louisiana State University Health Sciences Center, Shreveport, LA 71103, USA
4Department of Pathology, William Beaumont Hospital, Royal Oak, MI 48073, USA

Received 26 August 2014; Revised 22 October 2014; Accepted 5 November 2014; Published 20 November 2014

Academic Editor: Rafael Noal Moresco

Copyright © 2014 Xu Zeng et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Objective. After filtration through glomeruli, β2-microglobulin is reabsorbed in proximal tubules. Increased urinary β2-microglobulin indicates proximal tubule injury and measurement of β2-microglobulin in urine is useful to determine the source of renal injury. Kidney injury molecule-1 (KIM-1) has been characterized as a selective proximal tubule injury marker. This study was designed to evaluate the correlation of urinary β2-microglobulin concentration and KIM-1 expression as evidence of proximal tubule injury. Methods. Between 2009 and 2012, 46 patients with urine β2-microglobulin (RenalVysion) had follow-up kidney biopsy. Diagnoses included glomerular and tubule-interstitial disease. Immunohistochemical staining for KIM-1 was performed and the intensity was graded from 0 to 3+. Linear regression analysis was applied to correlate the values of urinary β2-microglobulin and KIM-1 staining scores. P < 0.05 was considered statistically significant. Results. Thirty patients had elevated urinary β2-microglobulin. KIM-1 staining was positive in 35 kidney biopsies. There was a significant correlation between urinary β2-microglobulin and KIM-1 staining (P < 0.05). Sensitivity was 86.6%, specificity was 43.7%, positive predictive value was 74.2%, and negative predictive value was 63.6%. Conclusion. Increased urinary β2-microglobulin is significantly correlated with KIM-1 staining in injured proximal tubules. Measurement of urine β2-microglobulin is a sensitive assay for proximal tubule injury.