Although there was a linear association between serum ROH and RBP4 (p < 0.001, R2 = 0.76), molar ratios for ROH:RBP4 showed a significantly different binding pattern at different CKD stages (Table 2), with the lowest ratios in CKD 4–5 and dialysis groups (0.72 and 0.59, respectively) compared with CKD 2–3 patients (0.81; p = 0.03);,suggesting relatively higher amounts of free RBP4 (apo-RBP) with advanced CKD. This evidence concerns the gene RBP4 and chronic kidney disease.