Sodium Bicarbonate Slows Chronic Kidney Disease Safely

Pam Harrison

June 18, 2019

BUDAPEST, Hungary — Sodium bicarbonate — long used, albeit sporadically, to correct metabolic acidosis in chronic kidney disease — is significantly better at slowing disease progression than standard care, and is safe, results from a large Italian trial indicate.

"One of the concerns about prescribing sodium bicarbonate to CKD patients has been that you might load patients with sodium and that could lead to fluid overload, uncontrolled blood pressure, and other unwanted effects," said Antonio Bellasi, MD, PhD, from the Bergamo Hospital in Italy.

But "it seems that sodium bicarbonate is very safe. We did not see any fluid overload or any other unwanted effects in patients who received it," he told Medscape Medical News. "While I think there should still be some caution when prescribing bicarbonate for patients," these concerns were not substantiated in the population we studied.

Bellasi presented results from the multicenter, randomized, unblinded Use of Bicarbonate in Chronic Renal Insufficiency (UBI) trial (NCT01640119) here at the European Renal Association–European Dialysis and Transplant Association 56th Congress.

"The UBI trial is the first large randomized trial to show that correction of acidosis was clearly associated with significantly slower progression of CKD," said Danilo Fliser, MD, from Saarland University Medical Center in Homburg, Germany.

Sodium bicarbonate is an uncomplicated intervention and it is dirt cheap, costing literally pennies a day to treat to serum bicarbonate targets, he told Medscape Medical News.

The UBI trial is the first large randomized trial to show that correction of acidosis was clearly associated with significantly slower progression of CKD.

Of the 740 patients in the study cohort, 376 received standard care plus sodium bicarbonate, and the remaining 364 patients, who served as the control group, received standard care alone.

"The majority of patients were CKD 3b and 4 patients, which is pretty much the kind of patients that most nephrologists see in community practice," Bellasi reported.

Mean age in the study cohort was 67.8 years, mean baseline creatinine clearance was 30 mL/min, and mean serum bicarbonate concentration was approximately 21.5 mmol/L.

At study entry, mean estimated glomerular filtration rate (eGFR) was 33.4 mL/min per 1.73 m² in the sodium bicarbonate group and 36.9 mL/min per 1.73 m² in the control group.

Target Bicarbonate

Target serum bicarbonate levels in the treatment group ranged from 24 to 28 mmol/L (metabolic acidosis is defined as levels below 22 mmol/L). To achieve target levels, the average dose of sodium bicarbonate was about 6 g/day, which translates to approximately 1.5 g/day of elemental sodium. This meant that patients in the treatment group took four to seven pills twice daily, which is a significant pill burden, Bellasi acknowledged.

At a mean follow-up of 32.9 months, "those randomized to sodium bicarbonate had a much better renal prognosis than those randomized to standard of care," he reported.

Of the 87 patients whose serum creatinine doubled during the study period, significantly fewer were in the treatment group than in the control group (25 vs 62; hazard ratio [HR], 0.36; P < .001).

"This signal was quite robust because even when we adjusted for multiple confounders, the estimated benefit was not changed," said Bellasi.

Of the 71 participants who initiated dialysis during the study period, significantly fewer were in the treatment group than in the control group (26 vs 45; HR, 0.5; P = .005).

The risk for all-cause mortality was also significantly lower in the sodium bicarbonate group than in the control group (25 vs 12; HR, 0.43; P = .01).

"The proportion of patients who required hospitalization remained much the same throughout the study period for standard-of-care patients, whereas patients randomized to sodium bicarbonate tended to have a decreased number of hospitalizations," Bellasi reported.

"Correction of metabolic acidosis is safe and significantly reduced CKD progression, as well as all-cause mortality, in these patients," he concluded.

The capsules are large and some patients might find them difficult to swallow, Fliser acknowledged, but "most of these patients understand that acidosis is not good for them" and can be convinced to take the pills.

Alternatively, at least in Italy, sodium bicarbonate can be purchased in powder form and mixed with water, a bit like Alka Seltzer, he explained.

If the target is to achieve a serum bicarbonate concentration of 24 to 28 mmol/L, patients can simply titrate the amount of powder they mix up or down. And once they achieve ideal serum levels, they can maintain a similar regimen indefinitely, he added.

This study was funded by the Italian Society of Nephrology. Bellasi has disclosed no relevant financial relationships. Fliser is a cofounder of DiaRen, the company that is currently marketing a DKK3 ELISA assay.

European Renal Association–European Dialysis and Transplant Association (ERA-EDTA) 56th Congress. Presented June 14, 2019.

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