Fig. 1From: Association of serum sodium minus chloride level at initiation of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers and hyperkalemia in patients with CKD: a case control studyRelationship between [HCO3−] and [Na+] − [Cl−] at the initiation of ACE-I or ARB. A. Scatter plot of [HCO3−] and [Na+] − [Cl−]. From the linear regression analysis, [Na+] − [Cl−] was significantly related with [HCO3−] (r = 0.67 and p < 0.001). B. Receiver operating curve analysis for [Na+] − [Cl−] for predicting metabolic acidosis ([HCO3−] < 24 mEq/L). From this analysis, 33.5 mEq/L had the highest Yoden indices (sensitivity + specificity − 1). Using this cutoff value, the sensitivity and specificity of [Na+] − [Cl−] for metabolic acidosis was 75.2% and 75.0%, respectively, while the area under the ROC curve was 0.81 (95% confidential interval 0.78–0.85). [HCO3−], serum bicarbonate level; [Na+], serum sodium level; [Cl−], serum chloride level; ACE-I, angiotensin-converting enzyme inhibitor; ARB, angiotensin receptor blockerBack to article page