Effects of Sodium Bicarbonate in CKD Stages 3 and 4: A Randomized, Placebo-Controlled, Multicenter Clinical Trial

Rationale & Objective: Metabolic acidosis associated with chronic kidney disease (CKD) may contribute to muscle dysfunction and bone disease. We aimed to test whether treatment with sodium bicarbonate improves muscle and bone outcomes. Study Design: Multicenter, randomized, placebo-controlled, clinical trial. Setting & Participants: 149 patients with CKD stages 3 and 4 between July 2011 and April 2016 at 3 centers in Cleveland, OH, and the Bronx, NY. Intervention: Sodium bicarbonate (0.4 mEq per kg of ideal body weight per day) (n = 74) or identical-appearing placebo (n = 75). Outcomes: Dual primary outcomes were muscle function assessed using sit-to-stand test and bone mineral density. Muscle biopsies were performed at baseline and 2 months. Participants were seen at baseline and 2, 6, 12, and 24 months. Results: Mean baseline serum bicarbonate level was 24.0 +/- 2.2 (SD) mEq/L and mean baseline estimated glomerular filtration rate was 36.3 +/- 11.2 mL/min/1.73 m(2). Baseline characteristics did not differ between groups. Mean serum bicarbonate levels in the intervention arm during follow-up were 26.4 +/- 2.2, 25.5 +/- 2.3, 25.6 +/- 2.6, and 24.4 +/- 2.8 mEq/L (at 2, 6, 12, and 24 months). These were significantly higher than in the placebo group (P < 0.001). Compared to the placebo group, participants randomly assigned to sodium bicarbonate treatment had no significant differences in sit-to-stand time (5 repetitions: P = 0.1; and 10 repetitions P = 0.07) or bone mineral density (P = 0.3). Sodium bicarbonate treatment caused a decrease in serum potassium levels that was of borderline statistical significance (P = 0.05). There were no significant differences in estimated glomerular filtration rates, blood pressure, weight, serious adverse events, or levels of muscle gene expression between the randomly assigned groups. Limitations: Initial mean serum bicarbonate level was in the normal range. Conclusions: Sodium bicarbonate therapy in patients with CKD stages 3 and 4 significantly increases serum bicarbonate and decreases potassium levels. No differences were found in muscle function or bone mineral density between the randomly assigned groups. Larger trials are required to evaluate effects on kidney function.