Chloride/sodium ratio and sodium-chloride difference in patients with renal failure and metabolic acidosis in hemodialysis treatment

Aim: The aim of the study is to evaluate the chloride/sodium ratio ([Cl-]/[Na+] ratio) and the sodium-chloride difference (Diff(Na-Cl)) in a group of patients with renal failure and metabolic acidosis receiving hemodialysis treatment. Materials and methods: Arterial blood samples were drawn from 62 patients, before and after 169 hemodialysis sessions; 114 of these samples came from clinically unstable (group A) and 55 from clinically stable (group B) patients. We measured these parameters: [Cl-]/[Na+] ratio, Diff(Na-Cl), [K+], partial pressure of carbon dioxide (PaCO2), [H+], standard bicarbonate concentration (SBC), base excess (BE), and anion gap (AG). Results: In group A the [Cl-]/[Na+] ratio was negatively correlated with AG only, while in group B it was positively correlated to [H+] and negatively to SBC, BE, and AG. After hemodialysis, both group A and group B showed a decrease in [Cl-]/[Na+] ratio, in K+, in [H+], and in AG, and an increase in Diff(Na-Cl), in PaCO2, in SBC, and in BE. After hemodialysis, as compared to baseline, the values of D% were different between the two groups with regard to Diff(Na-Cl), SBC, and BE, the variations of which were higher in group B. Conclusion: In this study, the [Cl-]/[Na+] ratio and the Diff(Na-Cl) seem to be correlated with the conventional parameters of the acid-base pattern. In the unstable group of patients, the [Cl-]/[Na+] ratio is negatively correlated with AG, while there is no correlation with lactate. This parameter might be useful to identify AG acidosis with normal lactate levels.