Another study [15] on subjects with CKD stages 2-4 also demonstrated that pNGAL concentr-ations were inversely associated with GFR and as kidney function declined to less than 30 ml/min, NGAL was a better biomarker of kidney failure compared to cystatin C. In contrast to our result, in Szewczyk et al. [25] study no significant correlation was found between eGFR and NGAL. This evidence concerns the gene CST3 and chronic kidney disease.