title: Urinary β2-Microglobulin Is a Good Indicator of Proximal Tubule Injury: A Correlative Study with Renal Biopsies.
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.
authors: Department of Pathology and Laboratory Medicine, Temple University Hospital, 3401 North Broad Street, Room A2-F326, 2PAP, Philadelphia, PA 19140, USA.
authors: Xu
authors: X
authors: Zeng
authors: Bostwick Laboratories, Orlando, FL 32809, USA.
authors: Deloar
authors: 0000-0002-9437-8498
authors: D
authors: Hossain
authors: Bostwick Laboratories, Orlando, FL 32809, USA.
authors: David G
authors: DG
authors: Bostwick
authors: Department of Pathology, Louisiana State University Health Sciences Center, Shreveport, LA 71103, USA.
authors: Guillermo A
authors: GA
authors: Herrera
authors: Department of Pathology, William Beaumont Hospital, Royal Oak, MI 48073, USA.
authors: Ping L
authors: PL
authors: Zhang