Correcting Metabolic Acidosis May Preserve Muscle Mass

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Oral sodium bicarbonate treatment was associated with improved lean body mass and kidney function in patients with metabolic acidosis due to CKD stages 3 and 4.
Oral sodium bicarbonate treatment was associated with improved lean body mass and kidney function in patients with metabolic acidosis due to CKD stages 3 and 4.

Oral sodium bicarbonate supplementation to correct metabolic acidosis in patients with chronic kidney disease (CKD) may improve muscles mass and kidney function, new study findings suggest.

The open-label study, led by P. S. Priyamvada, MD, DM , of the Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER)  in Puducherry, India, found that, among patients with similar LBM and estimated glomerular filtration rate (eGFR) at baseline, those who received sodium bicarbonate had significantly higher LBM and eGFR after 6 months than those who did not.

In patients with CKD, metabolic acidosis is associated with more rapid deterioration of kidney function and increased mortality as well as enhanced muscle catabolism, decreased protein synthesis, and other abnormalities, the authors explained. Although the condition is a recognized risk factor for morbidity, mortality, and disease progression, they noted, only limited data are available regarding the safety and effectiveness of metabolic acidosis correction in patients with predialysis CKD.

In an open-label prospective study, a team, randomly assigned 188 patients with CKD stages 3 or 4 and metabolic acidosis (venous bicarbonate level below 22 mEq/dL) to receive standard care alone or in combination with generic sodium bicarbonate tablets to maintain venous bicarbonate levels at 24 to 26 mEq/L. The starting dose of sodium bicarbonate was 0.5 mEq/kg of body weight. Investigators instructed patients to take the tablets 1 hour after eating to decrease gastrointestinal adverse effects. Medication adherence was checked by pill counts on monthly follow-up visits.

At baseline, the intervention and control groups had similar baseline characteristics, with no significant differences in age (50 years in both arms), causes of CKD, comorbidities (diabetes mellitus, systemic hypertension, coronary disease), mean eGFR (29.2 and 31.5 mL/min/1.73 m2, respectively), mean weight (54 and 53.8 kg), mean body mass index (21.2 and 21.3 kg/m2), MAMC (22.8 and 22.9 cm), LBM (36.5 and 36.2 kg), and fat mass (15.6 and 15.6 kg).

After 6 months, the intervention group demonstrated significantly higher LBM than the control arm (36.8 vs 36) as well as mid-arm muscle circumference (MAMC, 22.9 vs 22.6 cm), Dr Priyamvada and her colleagues reported online ahead of print in Nephrology Dialysis Transplantation. The estimated glomerular filtration rate was significant higher in the intervention than the control arm (32.74 vs 28.2 mL/min/1.73 m2). In addition, a significantly greater proportion of patients in the control arm than the intervention group experienced a rapid decline in eGFR (41.5% vs 20.2%), defined as a greater than 3 mL/min/1.73 m2 decrease.

In an acknowledgement of study limitations, Dr Priyamvada's group pointed out that, despite being significant, the magnitude in changes in muscle mass were small. In addition, the study, being open-label, was susceptible to observer bias.

Reference

Dubey AK, Sahoo J, Vairappan B, et al. Correction of metabolic acidosis improves muscle mass and renal function in chronic kidney disease stages 3 and 4: a randomized controlled trial. Nephrol Dial Transplant. 2018; published online ahead of print.

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