Clinical Significance of Urinary Biomarkers in Patients With Primary Focal Segmental Glomerulosclerosis.

BACKGROUND: Focal segmental glomerulosclerosis (FSGS) is often accompanied with tubulointerstitial lesion. This study aimed to assess the role of urinary biomarkers in predicting tubulointerstitial lesion and treatment response in FSGS patients.

METHODS: Urinary neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), N-acetyl-β-d-glucosaminidase (NAG) and retinol-binding protein (RBP) were measured in 32 FSGS patients and 22 patients with minimal change nephrotic syndrome. Patients with FSGS were followed up to investigate the value of these markers in predicting treatment response.

RESULTS: FSGS patients had higher urinary NGAL, NAG and RBP than patients with minimal change nephrotic syndrome with comparable proteinuria. A cutoff value of 15.87ng/mL NGAL demonstrated 87.1% sensitivity and 59.1% specificity for the diagnosis of FSGS, with an area under the receiver operator characteristic curve of 0.801. In FSGS, these markers correlated significantly with the degree of acute tubulointerstitial damage but not with chronic tubulointerstitial lesion. Response to immunosuppressive therapy was significantly different in patients with KIM-1, NAG and RBP levels below and above the cutoff values.

CONCLUSIONS: Urinary NGAL, KIM-1, NAG and RBP are reliable biomarkers of tubulointerstitial lesion in FSGS patients. The measurements of these markers may be useful in diagnosing FSGS, detecting acute tubulointerstitial lesion and predicting treatment response.