Correction of metabolic acidosis improves muscle mass and renal function in chronic kidney disease stages 3 and 4: a randomized controlled trial.

Background: Metabolic acidosis (MA) is associated with a loss of muscle mass and faster deterioration of kidney function in patients with chronic kidney disease (CKD). A few single-centre randomized trials have reported favourable outcomes following correction of MA. Additional good quality evidence on the safety and efficacy of alkali supplementation is required in epidemiologically different patient subsets with CKD.

Methods: A single-centre, open-label, randomized, prospective parallel-group study was conducted to assess the effect of correction of MA on body composition and kidney function. A total of 188 patients with CKD stages 3 and 4, with venous bicarbonate levels <22 mEq/L were randomized. The intervention arm received standard care as per Kidney Disease: Improving Global Outcomes (KDIGO) 2012 guidelines along with oral sodium bicarbonate supplementation to maintain venous bicarbonate levels at 24-26 mEq/L, whereas the control group received standard care alone. The mid-arm muscle circumference (MAMC), lean body mass (LBM) and estimated glomerular filtration rate (eGFR) were compared between the groups at the end of 6 months.

Results: The intervention arm showed a higher LBM {36.8 kg [95% confidence interval (CI) 36.5-37.1] versus 36 [35.7-36.4]; P = 0.002} and MAMC [22.9 cm (95% CI 22.8-23) versus 22.6 (22.5-22.7); P = 0.001] when compared with the control group. The GFR in the intervention arm was higher [32.74 mL/1.73 m2 (95% CI 31.5-33.9) versus 28.2 (27-29.4); P ≤ 0.001]. A rapid decline in GFR was documented in 39 (41.5%) patients in the control arm and 19 (20.2%) patients in the intervention arm (P = 0.001).

Conclusions: Alkali supplementation to increase venous bicarbonate levels to 24-26 mEq/L is associated with preservation of LBM and kidney function in patients with CKD stages 3 and 4.