Figure 2
Linear regression analysis between each urinary biomarker and the IDMS-traceable MDRD GFR (left column), CKD-EPI GFR (middle column), and TKV (right column). Biomarker concentrations and TKVs were log-transformed to fulfill the requirement of a normal distribution of the residuals. Urinary NAG levels showed a better association with the IDMS-traceable MDRD GFR (r 2 = 0.153), CKD-EPI GFR (r 2 = 0.194), and TKV (r 2 = 0.113) compared with other urinary biomarkers (P < 0.001). NAG (A); β2-microglobulin (B); NGAL (C); KIM-1 (D). sCr, serum creatinine; GFR, glomerular filtration rate; KIM-1, kidney injury molecule-1; NAG, N-acetyl-β-D-glucosaminidase; NGAL, neutrophil gelatinase-associated lipocalin; TKV, total kidney volume.