Clinical application of neutrophil gelatinase-associated lipocalin in the revised chronic kidney disease classification

Background: A revised classification of chronic kidney disease (CKD) was proposed by the Kidney Disease: Improving Global Outcomes (KDIGO) in 2012. Neutrophil gelatinase-associated lipocalin (NGAL) was considered as one of the most promising biomarkers in clinical nephrology. The aim of this study was to examine the level of NGAL in patients with different impairment of GFR based on the new classification, and to evaluate whether NGAL in serum or urine was associated with different risk categories in CKD patients. Methods: A cross-sectional study was performed in 240 patients with CKD. NGAL, serum cystatin C, beta(2)-macroglobulin (beta(2)-MG), urine alpha(1)-macroglobulin (alpha(1)-MG) and albuminuria were tested in patients with various degrees of renal impairment. Results: Good correlation was found between the NGAL and the cystatin C, beta(2)-MG and the alpha(1)-MG (r > 0.7). The level of sNGAL in CKD stage 3b was more than that in CKD stage 3a (P = 0.025). The concentration of the NGAL increased progressively with the increasing of risk categories (proposed by the revised CKD classification). The cutoff value of NGAL was calculated from stage 2 to stage 5. ROC analysis showed good AUC (sNGAL > 0.8, uNGAL > 0.7) and high specificity (sNGAL > 87%, uNGAL > 90%) on the cutoff value of NGAL. Conclusion: The results confirm NGAL as a useful biomarker in clinical nephrology which is helpful to diagnosis and evaluate the categories for CKD proposed by the KDIGO.