Metabolic acidosis in patients with chronic kidney disease (CKD) is associated with a higher incidence of kidney stones and shorter time to incident stone formation, investigators reported at the American Society of Nephrology’s Kidney Week 2021.

Patients with metabolic acidosis at the index date (the date of the first serum bicarbonate test) experienced kidney stones during follow-up at a higher frequency than those with normal serum bicarbonate levels (12% vs 9.5%), Vandana Mathur, MD, of MathurConsulting in Woodside, California, and colleagues reported in a poster presentation. Each 1 mEq/L increment in baseline serum bicarbonate was significantly associated with a 3.3% lower risk of kidney stone development in adjusted analyses, Dr Mathur and colleagues reported.

The study included 142,884 patients with nondialysis CKD, of whom 8305 had metabolic acidosis and 134,579 had normal serum bicarbonate levels. The authors defined metabolic acidosis as serum bicarbonate values of 12 or higher but less than 22 mEq/L and normal bicarbonate levels as 22 mEq/L or higher but less than 30 mEq/L. The study had a median follow-up period of 2.5 years (maximum 9.5 years).


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Patients with metabolic acidosis had a higher rate of kidney stone-related hospitalizations during follow-up compared with those who had normal bicarbonate levels during follow-up (39.8 vs 18.7 hospitalizations per 1000 patient-years), according to the investigators.

The study also identified other risk factors for kidney stone development. Compared with non-Hispanic White race, Black, Asian, and Hispanic race/ethnicity were significantly associated with a 30%, 27%, and 18% lower risk for incident kidney stones, respectively. Male sex vs female sex was significantly associated with 1.2-fold increased risk. Hyperoxaluria and a history of kidney stones were significantly associated with 2.9- and 9.9-fold increased risks, respectively.

Disclosure: The study was funded by Tricida, Inc.

Reference

Mathur V, Reaven NL, Funk SE, Lai J, Tangri N. Higher risk of incident kidney stones in patients with metabolic acidosis and chronic kidney disease. Presented at: Kidney Week 2021, November 2-7, 2021. Poster PO1162.