Serum neutrophil gelatinase-associated lipocalin as a marker of renal function in children with chronic kidney disease

Very few biomarkers exist for monitoring chronic kidney disease (CKD). We have recently shown that serum neutrophil gelatinase-associated lipocalin (NGAL) represents a novel biomarker for early identification of acute kidney injury. In this study, we hypothesized that serum NGAL may also represent a biomarker for the quantitation of CKD. Forty-five children with CKD stages 2-4 were prospectively recruited for measurement of serum NGAL, serum cystatin C, glomerular filtration rate (GFR) by Ioversol clearance, and estimated GFR (eGFR) by Schwartz formula. Serum NGAL significantly correlated with cystatin C (r=0.74, P < 0.000). Both NGAL and cystatin C significantly correlated with measured GFR (r=0.62, P < 0.000; and r=0.71, P < 0.000, respectively) as well as with eGFR (r=0.66, P < 0.000 and r=0.59, P < 0.000, respectively). At GFR levels of >= 30 ml/min per 1.73 m(2), serum NGAL, cystatin C, and eGFR were all significantly correlated with measured GFR. However, in subjects with lower GFRs (< 30 ml/min per 1.73 m(2)), serum NGAL levels correlated best with measured GFR (r=0.62), followed by cystatin C (r=0.41). We conclude that (a) both serum NGAL and cystatin C may prove useful in the quantitation of CKD, and (b) by correlation analysis, NGAL outperforms cystatin C and eGFR at lower levels of measured GFR.