Sodium bicarbonate, which is commonly used to treat metabolic acidosis in patients with chronic kidney disease (CKD), is hypothesized to increase the risk for calcium phosphate kidney stones by increasing urinary pH. New study findings presented at the virtual National Kidney Foundation 2021 Spring Clinical Meetings suggest that although sodium bicarbonate does increase urinary pH, it significantly raises urinary citrate levels, which may mitigate the risk for calcium phosphate stones.
A team led by Kalani Raphael, MD, of Oregon Health & Science University in Portland, and colleagues studied 168 patients with CKD who participated in the randomized BASE (Bicarbonate Administration to Stabilize eGFR) Pilot Trial. Of these, 76 received higher-dose (0.8 mEq/kg/d) and 47 received lower-dose (0.5 mEq/kg/d) oral sodium bicarbonate, and 45 received placebo.
Compared with placebo, the higher-dose and lower-dose sodium bicarbonate groups experienced a significant mean 0.97 and 0.77 increase in urinary pH from baseline, Dr Raphael’s group reported in a poster presentation. Urinary citrate/creatinine concentration increased significantly by a mean 145.7% and 108.3% in the higher-dose and lower-dose sodium bicarbonate groups, respectively. Sodium bicarbonate had no effect on urinary calcium or phosphate.
“I don’t think these findings should totally alleviate concerns about promoting calcium phosphate stones,” Dr Raphael told Renal & Urology News, “but we understand some of the chemical changes that happen with sodium bicarbonate a little bit better.”
Fong PS, Larive B, Kendrick C, et al. Effect of oral sodium bicarbonate on calcium-phosphate nephrolithiasis risk in chronic kidney disease: a secondary analysis of the BASE Pilot Trial. Presented at the virtual National Kidney Foundation 2021 Spring Clinical Meetings, April 6-10. Poster 185.