Hyperchloremic acidosis develops at the stage G4 and shifts to high anion gap acidosis at the stage G5 in chronic kidney disease

Background Amelioration of hyperchloremic acidosis (Cl-Ac), a common complication in chronic kidney disease (CKD), could preserve renal function in chronic kidney disease (CKD). However, the development of Cl-Ac in CKD has not been clarified yet. Methods The degree of Cl-Ac, which is indicated as the bicarbonate concentration decrease with serum chloride concentration increase (∆[HCO 3 – ] Cl ), was compared with the estimated glomerular filtration rate (eGFR) by using CKD patient records. Results In 307 records with metabolic acidosis, a spline curve obtained from the plot comparing ∆[HCO 3 – ] Cl with eGFR showed that ∆[HCO 3 – ] Cl did not change, increased, and decreased during eGFR decrease until 27, from 27 to 17.5, and from 17.5 mL/min/1.73 m 2 , respectively. Conclusion By CKD progression, Cl-Ac progressed and regressed at the CKD stages G4 and G5, respectively. The regression would have reflected the shift of Cl-Ac to high anion gap acidosis.