Metabolic Acidosis in CKD: How Bicarbonate Therapy Slows Kidney Decline

What Is Metabolic Acidosis in Chronic Kidney Disease?

When your kidneys aren’t working well, they can’t get rid of the extra acid your body makes every day. This leads to metabolic acidosis - a condition where your blood becomes too acidic because bicarbonate, your body’s natural buffer, drops below 22 mEq/L. It’s not rare. About 15% of people with stage 3 CKD have it. By stage 5, that number jumps to over 40%. Most don’t feel symptoms at first - no pain, no fever. But over time, this low bicarbonate level quietly damages your bones, wastes your muscles, and speeds up kidney failure.

Why Bicarbonate Matters in CKD

Your kidneys normally make bicarbonate to neutralize acid from food, metabolism, and daily wear and tear. When kidney function drops below 30%, this production slows. Without enough bicarbonate, your body starts pulling calcium from your bones to neutralize acid. That’s why many CKD patients develop osteoporosis even without vitamin D deficiency. Muscle breakdown also increases - you lose strength, get tired faster, and struggle to walk or climb stairs. Studies show that keeping bicarbonate above 22 mEq/L can slow the decline of your eGFR by nearly 6 mL/min/year. That’s the difference between reaching dialysis in 8 years versus 5.

Sodium Bicarbonate: The Most Common Treatment

The go-to fix for metabolic acidosis in CKD is sodium bicarbonate. It’s cheap, effective, and available as tablets or powder. A typical tablet is 650 mg - that’s 7.6 mEq of bicarbonate. Some people mix baking soda (sodium bicarbonate powder) in water. One teaspoon equals about 50 mEq. But here’s the catch: each 500 mg tablet has 610 mg of sodium. For someone with high blood pressure or heart failure, that’s dangerous. A 2020 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. Still, it works. In a 3-year trial with 740 patients, those taking sodium bicarbonate saw their bicarbonate levels rise by 4-6 mEq/L and their kidney function decline slowed significantly.

Alternatives to Sodium Bicarbonate

If you can’t handle the sodium, there are other options. Calcium citrate is one. It gives you bicarbonate without the sodium, and it also helps with bone health. But you have to take a lot of pills - sometimes six a day - and there’s a risk of too much calcium in your blood, which can cause kidney stones. Studies show a 27% higher chance of stones in people on long-term calcium supplements.

Potassium citrate sounds good because it’s alkali and low in sodium. But if you have CKD, your potassium is often already high. Giving more potassium can push levels over 5.0 mEq/L, which can cause dangerous heart rhythms. One study found 22.4% of stage 4 CKD patients developed dangerous hyperkalemia on potassium citrate. So doctors avoid it unless you’re low on potassium - which is rare in advanced CKD.

Then there’s veverimer. It was supposed to be the game-changer - a pill that traps acid in your gut without being absorbed. No sodium. No potassium. Just acid removal. Phase 2 trials looked promising. But the big phase 3 trial in 2021 missed its target. The FDA didn’t approve it. The company is trying again with new data, but as of late 2023, it’s not available.

Dietary Changes: The Quiet Hero

Food plays a bigger role than most people realize. Meat, cheese, eggs, and processed grains create acid. Fruits and vegetables? They make your body more alkaline. A diet rich in produce can cut your daily acid load by 40-60 mEq. That’s like taking a full tablet of bicarbonate every day - without the side effects. One patient in Cleveland Clinic’s program raised their bicarbonate by 3.5 mEq/L in six months just by swapping beef for beans and adding three extra servings of spinach and apples daily. The problem? It’s hard. Most people don’t know which foods are acid or base. A banana is base-producing (-2.2 mEq/100g). A slice of cheddar cheese? Acid-producing (+8.0 mEq/100g). Renal dietitians use a tool called PRAL to measure this, but only 35% of patients ever reach a neutral PRAL score. It takes time, education, and support.

Who Gets Treated - And Who Doesn’t

Despite clear guidelines, most people with metabolic acidosis aren’t getting treatment. A 2023 analysis found only 43% of eligible CKD patients received alkali therapy. The gaps are real: Black patients were treated 9% less often than white patients. Rural patients had 14% lower rates than urban ones. Why? Some doctors don’t test bicarbonate regularly. Others fear side effects. Some patients can’t afford pills or can’t swallow six a day. One Reddit user said the baking soda powder tasted so bad they had to mix it in orange juice - adding sugar they shouldn’t have. Another said their blood pressure shot up after two weeks on sodium bicarbonate. These aren’t just anecdotes - they’re barriers to care.

How Doctors Decide What to Prescribe

There’s no one-size-fits-all. Most nephrologists start with diet. If bicarbonate stays below 22 mEq/L after three months, they add alkali. Sodium bicarbonate is first-line unless you have heart failure, edema, or high blood pressure. Then they switch to calcium citrate. Potassium citrate? Almost never in stage 3b-5. Dosing starts low - one 650 mg tablet once or twice a day. Then they check bicarbonate levels every month until it’s stable. The goal? Keep it between 23 and 29 mEq/L. But new data suggests even 22 mEq/L might be enough to protect your kidneys. The 2024 KDIGO draft now recommends 22-29 mEq/L, recognizing that pushing too high might hurt older or frail patients. Some experts now say: aim for 24-26 mEq/L if you have heart issues. For someone thin and malnourished, 22-24 might be safer.

Monitoring and What to Watch For

If you’re on treatment, you need regular blood tests. Every 3-6 months if you’re stable. Monthly if you just started or changed doses. Watch for:

• Swelling in legs or ankles (fluid retention from sodium)
• High blood pressure spikes
• Leg cramps or muscle weakness (could be low calcium or potassium)
• Constipation or bloating (common with calcium or citrate)

Also, track your calcium and potassium. Calcium above 10.5 mg/dL? That’s too high. Potassium above 5.0 mEq/L? That’s risky. Your doctor should check these every time they check bicarbonate.

The Future of Treatment

Research is moving fast. The COMET-CKD trial is testing high-dose versus low-dose sodium bicarbonate in 1,200 patients. Results come in late 2025. A new supplement called TRC001, which doesn’t use citrate, is showing fewer stomach issues and a 4.1 mEq/L bicarbonate boost in early trials. Meanwhile, the global market for these treatments is growing - $1.2 billion in 2022, mostly from generic sodium bicarbonate. But the real win isn’t a new pill. It’s catching acidosis early and treating it before it steals your muscle, your bones, or your kidney function. The National Institute of Diabetes and Digestive and Kidney Diseases estimates that fixing this could prevent 28,000 cases of kidney failure each year in the U.S. alone. That’s not just science - it’s quality of life.

What You Can Do Today

If you have CKD, ask your doctor for a serum bicarbonate test. If it’s below 22 mEq/L, don’t wait. Ask about diet first. Can you add more apples, oranges, broccoli, or potatoes to your meals? Can you cut back on processed meats and cheese? If diet isn’t enough, ask about sodium bicarbonate - but tell them if you have high blood pressure or heart problems. If you’re on pills, track how many you take daily. If it’s more than four, talk about alternatives. And if you’re struggling with taste or side effects, tell your doctor. There are options. You don’t have to suffer in silence.