Clinicopathological role of kidney injury molecule-1 in immunoglobulin A nephropathy

BACKGROUND Urinary kidney injury molecule-1 (KIM-1) is an early and sensitive biomarker of acute kidney injury, but it is unclear if it is a biomarker of chronic glomerulonephritis. We evaluated whether urinary KIM-1 levels in patients with immunoglobulin A (IgA) nephropathy can be a marker to reflect clinicopathological severity and predict the prognosis. METHODS We measured urinary KIM-1 levels in 40 patients (15 males; mean age 36.6±12.9 years) with IgA nephropathy and 10 healthy people (5 males; mean age 37.3±9.6 years) as controls. The correlation of urinary KIM-1 levels with patients' clinical parameters, histological grades, and follow-up data were analyzed using the modified H. S. Lee grading system and tubulointerstitial change scores. RESULTS Urinary KIM-1 levels were higher in patients with IgA nephropathy than healthy controls (P=0.001). Univariate and multivariate regression analyses showed that urinary KIM-1 levels had a direct correlation with H. S. Lee grade and tubulointerstitial inflammation (P=0.004 and P=0.011, respectively). CONCLUSION In patients with IgA nephropathy, urinary KIM-1 has a significant correlation with histopathologic severity.