We divided the CKD study population into five groups according to stages of eGFR as defined in Kidney Disease: Improving Global Outcomes for CKD.[26] The NGAL levels of each respective stage were: 157.6 ± 64.04 ng/mL, 228.3 ± 127.3 ng/mL, 346.9 ± 159.4 ng/mL, 552.9 ± 323.5 ng/mL, and 729.5 ± 282.7 ng/mL (P < 0.001; Table 1). Here, LCN2 is linked to chronic kidney disease.