What Is Metabolic Acidosis in Chronic Kidney Disease?
When your kidneys start to fail, they can't remove enough acid from your blood. That’s when metabolic acidosis kicks in. It’s not just a lab number-it’s a silent driver of muscle loss, bone breakdown, and faster kidney decline in people with chronic kidney disease (CKD). By the time someone reaches stage 3 CKD, about 1 in 7 have this condition. By stage 5, it’s more than 4 in 10. The core problem? Serum bicarbonate drops below 22 mEq/L. Normal is 22-29. When it falls, your body starts eating its own muscle and bone to buffer the acid.
Why Bicarbonate Matters More Than You Think
Bicarbonate isn’t just a buffer. It’s a lifeline. In healthy kidneys, bicarbonate is regenerated every day to neutralize the acid from food, metabolism, and daily wear and tear. But in CKD, that system breaks down. The kidneys can’t make enough new bicarbonate, and they can’t flush out the acid. That’s why low bicarbonate is one of the strongest predictors of how fast CKD will progress. Studies show that keeping bicarbonate above 22 mEq/L cuts the risk of kidney function dropping by half over two years. The goal isn’t just to fix a number-it’s to protect your body from wasting away.
How Sodium Bicarbonate Works (and Why It’s Not for Everyone)
Sodium bicarbonate tablets are the most common treatment. Each 650mg tablet gives you 7.6 mEq of bicarbonate. A typical starting dose is one or two tablets a day. In a major 3-year trial, patients taking this treatment slowed their eGFR decline by nearly 6 mL/min compared to those who didn’t. But here’s the catch: each tablet also adds 610mg of sodium. For someone with high blood pressure or heart failure, that’s dangerous. One study found that CKD patients on sodium bicarbonate had a 32% higher chance of being hospitalized for heart failure than those on calcium-based alternatives. If you’re on diuretics or have swelling in your legs, your doctor will think twice before prescribing this.
Alternatives to Sodium Bicarbonate
Not everyone can take sodium bicarbonate. That’s where other options come in. Calcium citrate is a popular substitute. Each 500mg tablet gives you 120mg of elemental calcium and helps neutralize acid without the sodium. But it comes with its own risk: too much calcium can lead to kidney stones or high blood calcium levels. One study showed a 27% higher chance of calcium stones in CKD patients on long-term calcium supplements.
Potassium citrate sounds ideal-it’s alkalinizing and helps prevent kidney stones. But in CKD, potassium builds up easily. About 18% of patients on potassium supplements develop dangerous high potassium levels (hyperkalemia). If your potassium is already above 4.5 mEq/L, this isn’t safe. The National Kidney Foundation specifically warns against using potassium citrate in stage 3b-5 CKD.
Then there’s veverimer-a drug designed to bind acid in the gut without being absorbed. It promised a sodium-free, potassium-free solution. Phase 2 trials showed promising results. But in its final phase 3 trial in 2021, it failed to hit its target. The FDA didn’t approve it. Tricida is trying again in 2024, but for now, it’s not an option.
Diet Can Be Your First Line of Defense
Before you start swallowing pills, look at your plate. The average Western diet produces 50-100 mEq of acid per day. Meat, cheese, processed grains-these are acid factories. Fruits and vegetables? They’re acid fighters. One study found that replacing just half your meat with plant-based foods lowered your dietary acid load by 40-60 mEq per day. That’s enough to raise serum bicarbonate by 1-3 mEq/L on its own.
But it’s not easy. A patient in Cleveland Clinic reported a 3.5 mEq/L rise in bicarbonate after six months of working with a dietitian to swap out chicken for lentils and cheese for avocado. The challenge? Most people don’t know which foods are acidic. A 100g serving of beef adds +9.5 mEq of acid. A banana? -2.2 mEq. Your kidneys don’t care about calories-they care about acid load. Learning the Potential Renal Acid Load (PRAL) score of foods takes time. Only 35% of CKD patients on dietary advice actually reach a neutral or negative PRAL score.
What the Guidelines Say (And What Doctors Actually Do)
KDIGO, the global kidney organization, says: start alkali therapy when bicarbonate drops below 22 mEq/L. That’s a strong recommendation backed by data from over 10,000 patients. The American Society of Nephrology agrees. But here’s the gap: only 43% of eligible CKD patients actually get treatment. Why? Some doctors don’t test bicarbonate regularly. Others worry about side effects. And some patients just can’t stick with the regimen.
A 2022 survey of 457 CKD patients found that 68% struggled with pill burden-averaging 4.2 tablets a day. 41% hated the taste of liquid bicarbonate. One Reddit user said they had to mix baking soda powder in orange juice just to swallow it, which added sugar they shouldn’t be consuming. Another patient on forums reported her blood pressure jumped from 130/80 to 160/95 after starting sodium bicarbonate. Her doctor switched her to calcium citrate, but now she takes six large pills daily and still gets leg cramps.
Monitoring and Personalizing Treatment
There’s no one-size-fits-all. Your target bicarbonate level depends on your other conditions. If you have heart failure, aim for 24-26 mEq/L. If you’re elderly and underweight, 22-24 might be safer. New data from the 2024 KDIGO draft suggests lowering the minimum target from 23 to 22 mEq/L, because even that small rise helps protect your kidneys.
Monitoring is key. Check bicarbonate every 3-6 months if you’re stable. If you’re starting treatment, check monthly. Watch for signs of too much alkali: nausea, bloating, swelling, or confusion. Too little? Fatigue, muscle weakness, or shortness of breath. Your doctor should also check your potassium, calcium, and blood pressure regularly.
The Big Picture: Why This Matters
Metabolic acidosis isn’t just a side effect of CKD-it’s a treatable cause of its progression. Fixing it could prevent 28,000 cases of kidney failure each year in the U.S. alone. That’s $1.4 billion in saved healthcare costs. But we’re not doing it. Too many patients slip through the cracks because we treat the symptoms, not the underlying imbalance. If you have CKD and your last blood test showed bicarbonate under 22, ask your doctor: "Have we addressed my acid load?" It’s a simple question. But it might be the most important one you ask this year.
What is metabolic acidosis in CKD?
Metabolic acidosis in CKD is when your blood becomes too acidic because your kidneys can’t remove acid or make enough bicarbonate. It’s diagnosed when serum bicarbonate falls below 22 mEq/L. This condition speeds up kidney damage, causes muscle loss, and weakens bones.
Is sodium bicarbonate safe for everyone with CKD?
No. Sodium bicarbonate can raise blood pressure and worsen heart failure or swelling because of its high sodium content. It’s risky for people with hypertension, heart disease, or edema. Your doctor should check your sodium levels and fluid status before prescribing it.
Can I treat metabolic acidosis with diet alone?
Yes, for mild cases. Eating more fruits and vegetables and less meat, cheese, and processed grains can lower acid load and raise bicarbonate by 1-3 mEq/L. But for most people with stage 3b-5 CKD, diet alone isn’t enough-you’ll likely need oral alkali therapy too.
Why is potassium citrate not recommended for CKD patients?
Potassium citrate can raise blood potassium levels dangerously high in CKD patients, especially those with stage 3b-5 disease. About 18-22% of patients develop hyperkalemia (>5.0 mEq/L) on potassium supplements, which can cause heart rhythm problems or even cardiac arrest.
What’s the best target for serum bicarbonate in CKD?
KDIGO recommends 23-29 mEq/L, but newer data suggests 22-29 is acceptable. For patients with heart failure, aim for 24-26. For older or frail patients, 22-24 may be safer. The goal is to balance kidney protection with avoiding side effects from overcorrection.
Is there a new drug for metabolic acidosis in CKD?
Veverimer was developed as a sodium-free alternative but failed its final trial in 2021 and isn’t approved. A new citrate-free alkali supplement called TRC001 is in early trials and shows promise with fewer stomach side effects. No new FDA-approved drugs are currently available for chronic metabolic acidosis in CKD.
How often should I get my bicarbonate checked?
If you have CKD and your bicarbonate is normal, check it every 6 months. If it’s low or you’re starting treatment, check it monthly until stable. Once you’re on a steady dose and feeling well, every 3-6 months is enough.
What to Do Next
If you have CKD and haven’t had your serum bicarbonate checked in the last year, ask your doctor for a basic metabolic panel. If it’s below 22 mEq/L, don’t wait. Ask about sodium bicarbonate, calcium citrate, or dietary changes. If you’re already on treatment but still feel tired, weak, or notice swelling, your dose may be off. Bring your pill bottles to your next appointment. Bring a food log. Ask if your acid load is being managed-not just your creatinine or eGFR. Your kidneys aren’t just failing-they’re being worn down by acid. And that’s something you can change.
Bryan Wolfe
January 11, 2026 AT 13:35