AQP1 and chronic kidney disease: Examination of uEV‐AQP1 or ‐AQP2 in the 19 patients with CKD G4 and G5, and those in the 15 normal healthy volunteers yielded a ROC AUC of 0.951 for AQP1 (95% confidence interval (CI), 0.888 to 1) and 0.884 for AQP2 (95% CI: 0.757–1) (Figure 3).