Prognostic value of NGAL staining in patients with IgA nephropathy

Renal tubulointerstitial injury plays an important role in disease progression of IgAN. Neutrophil gelatinase-associated lipocalin (NGAL) is a stress protein released by tubular cells. NGAL is a promising biomarker of acute kidney injury. There is a growing literature suggesting that NGAL is also a marker of chronic kidney disease and severity. Our aim was to evaluate the prognostic value of NGAL staining in patients with IgAN.

This retrospective study included all consecutive patients who underwent a renal biopsy at our center between January 2005 and December 2009. Forty-five patients with IgA nephritis were enrolled, and renal biopsy specimens of 29 patients were evaluated. We evaluated baseline age, sex, hypertension, serum creatinine, glomerular filtration rate (GFR), urine protein, NGAL staining, glomerulosclerosis, interstitial fibrosis, and extracapillary proliferation. The primary endpoint of this study was doubling of baseline serum creatinine and/or the onset of ESRD in the course of the study. At the end of the follow-up, patients whose estimated GFR (eGFR) was ≤15 mL/min/1.73 m(2) and/or baseline serum creatinine doubled, were defined as the progressor group.

Nineteen patients (65.5%) were NGAL positive and 10 patients (34.5%) were NGAL negative. Female gender and hypertension were associated with NGAL-positive staining. Urinary protein excretion and serum creatinine levels were more elevated in the NGAL-positive group, but the difference was not significant. We found NGAL-positive staining in major proportion in the progressor group (88.9%) than the non-progressor group (55%) (p = 0.076).

NGAL staining can be a new histological marker in IgAN progression.