What Is Metabolic Acidosis in Chronic Kidney Disease?
When your kidneys can’t remove enough acid from your blood, your body becomes too acidic. This is called metabolic acidosis. In people with chronic kidney disease (CKD), this isn’t rare-it’s common. By stage 3, about 15% of patients have it. By stage 5, that number jumps to over 40%. The main sign? Low serum bicarbonate-below 22 mEq/L. Normal levels are 23 to 29 mEq/L. When bicarbonate drops, your body starts breaking down muscle to buffer the acid. Your bones weaken. Your heart works harder. And your kidneys decline faster.
It’s not just a lab number. It’s a signal your body is under stress. For years, doctors treated it as a side effect of CKD. Now, we know it’s a driver of progression. Correcting it isn’t optional-it’s part of slowing the disease.
Why Bicarbonate Matters
Bicarbonate is your blood’s natural buffer. It neutralizes acid so your pH stays around 7.35 to 7.45. In healthy kidneys, bicarbonate is regenerated and acid is excreted. In CKD, that system breaks down. The kidneys can’t make enough new bicarbonate, and acid builds up. That’s why treatment focuses on replacing what’s missing.
Oral sodium bicarbonate is the most common fix. A 650mg tablet gives you about 7.6 mEq of bicarbonate. Some patients take two or three a day. Studies show this can raise serum bicarbonate by 4 to 6 mEq/L in a few months. But it’s not just about fixing the number. The real win? Slowing kidney decline. One 3-year trial found patients on bicarbonate lost eGFR at a rate 5.9 mL/min/1.73m² slower than those on placebo. That’s the difference between reaching dialysis in 10 years versus 6.
Who Should Get Bicarbonate Therapy?
KDIGO guidelines say: start alkali therapy when serum bicarbonate falls below 22 mEq/L. That’s a Grade 1B recommendation-strong, based on solid evidence. But not everyone gets it. A 2023 analysis found only 43% of eligible CKD patients receive treatment. Why? Fear of side effects, lack of awareness, or just not testing bicarbonate regularly.
It’s not just for advanced CKD. Even in stage 3, if bicarbonate is low, treatment helps. The CRIC study showed patients with bicarbonate ≥22 mEq/L had a 23% lower risk of kidney failure or a 50% drop in eGFR. That’s why experts like Dr. L. Lee Hamm say correcting acidosis should be standard care for all CKD stages 3 to 5.
The Sodium Problem
Every 500mg sodium bicarbonate tablet contains 610mg of sodium. That’s a lot if you have high blood pressure, heart failure, or swelling. A 2020 study found CKD patients on sodium bicarbonate had a 32% higher risk of hospitalization for heart failure compared to those on calcium citrate.
This is why many nephrologists hesitate. They see the benefit but worry about the cost. The solution? Don’t skip treatment-choose wisely. If you’re fluid-sensitive, start low: one 650mg tablet daily. Monitor blood pressure and weight weekly. If your numbers climb, switch to a sodium-free option.
Alternatives to Sodium Bicarbonate
- Calcium citrate: Each 500mg tablet has 120mg of elemental calcium. It’s sodium-free and helps bone health. But too much can raise calcium levels and increase kidney stones. Limit to 1,000mg elemental calcium daily.
- Potassium citrate: Good for people with low potassium. But if your potassium is already above 4.5 mEq/L (common in CKD), this can push you into dangerous hyperkalemia. Studies show 22.4% of stage 4 patients on potassium citrate developed potassium levels over 5.0 mEq/L.
- Sodium citrate (Shohl’s solution): Liquid form, easier to dose. But it still has sodium. And many patients hate the taste-some mix it with orange juice, adding sugar they shouldn’t have.
- Dietary changes: Eat more fruits and vegetables. They’re base-producing. Apples, broccoli, spinach, and bananas reduce acid load. Meat, cheese, and processed grains are acid-forming. A diet with 5-9 servings of produce daily can cut acid load by 40-60 mEq/day. One patient in Cleveland Clinic raised bicarbonate by 3.5 mEq/L in six months just by swapping meat for beans and greens.
Why Veverimer Failed
For years, a drug called veverimer was the hope for sodium-free alkali therapy. It binds acid in the gut without being absorbed. Phase 2 trials looked great-bicarbonate rose by 4.3 mEq/L in 12 weeks. But the phase 3 trial in 2021 missed its goal. The difference vs. placebo was 2.07 mEq/L-statistically insignificant. The FDA didn’t approve it. The company plans to resubmit in 2024 with new data, but right now, it’s not an option.
This highlights a bigger problem: we need better drugs. But until then, we work with what we have.
Monitoring and Dosing
Don’t start high. Start low and go slow. Most nephrologists begin with 650mg sodium bicarbonate once or twice daily. Recheck serum bicarbonate in 4 to 6 weeks. Adjust dose by 650mg every 2 to 4 weeks until you hit 23-29 mEq/L. Once stable, test every 3 to 6 months.
Watch for side effects: bloating, nausea, swelling, or rising blood pressure. If you’re on calcium citrate, check serum calcium every 3 months. If potassium citrate is used, check potassium weekly at first. And always, always track your diet. Many patients don’t realize how much acid they’re eating.
The Real Barrier: Adherence
A 2022 survey of 457 CKD patients found 68% struggled with pill burden-averaging 4.2 tablets a day. 41% hated the taste of liquid forms. 29% had stomach issues. That’s why many stop.
One patient on Reddit said he had to mix baking soda powder in orange juice just to swallow it. Another said her legs cramped after switching to calcium citrate. These aren’t just complaints-they’re reasons treatment fails.
The best solution? Combine therapy with support. Work with a renal dietitian. Learn which foods help and which hurt. Use a PRAL score calculator (Potential Renal Acid Load) to track your daily acid intake. Target: below 0 mEq/day. Only 35% of patients hit that, even with counseling.
What’s Next?
The COMET-CKD trial, enrolling 1,200 patients, is testing high-dose vs. low-dose bicarbonate. Results come in late 2025. Early data on a new citrate-free alkali supplement (TRC001) shows promise-better tolerance, similar bicarbonate boost.
KDIGO’s 2024 draft update suggests lowering the treatment threshold from 23 to 22 mEq/L. Why? Because even 22 still protects the kidneys. And they’re pushing for personalized targets: 24-26 mEq/L for heart failure patients, 22-24 for elderly or malnourished ones.
But the biggest opportunity isn’t a new drug. It’s better screening. If every CKD patient had their bicarbonate checked every 6 months, we could prevent 28,000 cases of kidney failure a year in the U.S. alone. That’s $1.4 billion saved. All because we paid attention to a simple blood number.
Key Takeaways
- Metabolic acidosis is common in CKD stages 3-5 and speeds up kidney damage.
- Serum bicarbonate below 22 mEq/L should trigger treatment per KDIGO guidelines.
- Sodium bicarbonate works-but can worsen heart failure or high blood pressure.
- Calcium citrate and dietary changes are safer alternatives for sodium-sensitive patients.
- Potassium citrate is risky unless you have low potassium.
- Adherence is the biggest hurdle. Taste, pill burden, and side effects cause many to quit.
- Dietary acid load matters. Aim for 5-9 servings of fruits and vegetables daily.
- Regular monitoring every 3-6 months is essential for safe, effective treatment.
