Metabolic Acidosis in CKD: How Bicarbonate Therapy Slows Kidney Decline

When your kidneys start to fail, they don’t just stop filtering waste-they also lose their ability to keep your blood’s acid levels in check. This leads to metabolic acidosis, a hidden but dangerous condition that accelerates kidney damage, breaks down muscle, and weakens bones. It’s not rare. In fact, nearly half of people with stage 5 chronic kidney disease (CKD) have it. Yet, most don’t know they have it-and even fewer get treated.

What Is Metabolic Acidosis in CKD?

Metabolic acidosis happens when your blood becomes too acidic because your kidneys can’t remove enough acid or make enough bicarbonate to neutralize it. Normal blood bicarbonate levels are between 22 and 29 mEq/L. When they drop below 22 mEq/L, you’re in metabolic acidosis. In early CKD (stage 3), about 15% of patients have it. By stage 5, that number jumps to 42%.

The kidneys normally get rid of acid through urine and make new bicarbonate to balance it. But when kidney function drops below 30%, this system breaks down. Acid builds up, and the body starts pulling calcium from bones to buffer it. Over time, this leads to osteoporosis. Muscle breaks down. Your heart works harder. And your kidneys decline faster.

Why Bicarbonate Therapy Matters

The goal of treatment is simple: raise serum bicarbonate back into the safe range. Sodium bicarbonate (baking soda) is the most common treatment. It’s cheap, widely available, and proven to work.

A major 3-year trial with 740 CKD patients showed that those taking sodium bicarbonate slowed their kidney decline by nearly 6 mL/min/1.73m² compared to those who didn’t. That’s the difference between reaching dialysis in 5 years versus 10. Another study found that keeping bicarbonate above 22 mEq/L lowered the risk of kidney failure or a 50% drop in kidney function by 23%.

But it’s not just about slowing kidney decline. Correcting acidosis also reduces muscle wasting. One study showed patients on bicarbonate maintained more muscle mass over two years than those left untreated. That’s huge for quality of life-especially for older adults who already struggle with weakness and falls.

How Bicarbonate Is Given

Most patients start with sodium bicarbonate tablets-usually 650 mg, which contains about 7.6 mEq of bicarbonate. The typical starting dose is one tablet once or twice daily. Doctors then adjust the dose every few weeks based on blood tests, aiming for a target of 23-29 mEq/L.

Some patients use baking soda powder. One teaspoon equals about 50 mEq of bicarbonate-far more than a tablet. But it’s messy, tastes terrible, and can cause bloating. Many mix it with orange juice to hide the flavor, but that adds sugar, which isn’t ideal for CKD.

For patients with high blood pressure or heart failure, sodium bicarbonate is risky. Each 500 mg tablet contains 610 mg of sodium. That’s like adding a small bag of chips to your daily intake. Too much sodium means fluid retention, swelling, and worse heart strain.

Alternatives to Sodium Bicarbonate

Not everyone can tolerate sodium bicarbonate. That’s where alternatives come in.

Sodium citrate (Shohl’s solution) is another alkali option. It’s liquid, easier to swallow for some, and provides similar bicarbonate levels. But it still contains sodium.

Potassium citrate sounds appealing-it doesn’t add sodium and can help prevent kidney stones. But in CKD, potassium levels are already high. Giving more potassium can push levels over 5.0 mEq/L, which is dangerous and can cause heart rhythm problems. Studies show 22% of CKD patients on potassium citrate develop hyperkalemia. So it’s avoided unless someone is low in potassium.

Calcium citrate is a sodium-free option. Each 500 mg tablet gives you 120 mg of elemental calcium. It’s often used for patients with heart failure. But too much calcium can lead to hardening of arteries, kidney stones, and high blood calcium. One study found a 27% higher rate of kidney stones in CKD patients on long-term calcium supplements.

A newer drug, veverimer, was designed to bind acid in the gut without adding sodium, potassium, or calcium. Early results looked promising. But in its final phase 3 trial in 2021, it missed its target. It raised bicarbonate by only 2.07 mEq/L-barely above placebo. The FDA didn’t approve it. Tricida Inc. plans to resubmit in 2024, but for now, it’s not an option.

Diet Can Help-But It’s Hard

Food plays a big role. Some foods make your body more acidic; others help neutralize acid.

Acid-producing foods: meat (+9.5 mEq per 100g), cheese (+8.0 mEq), white bread, and processed grains.

Base-producing foods: fruits (-2.2 mEq), vegetables (-2.8 mEq), potatoes, and legumes.

A diet rich in fruits and vegetables can reduce your daily acid load by 40-60 mEq. That’s like taking 5-8 bicarbonate tablets a day-without the side effects.

But changing your diet is tough. Most people don’t know which foods are acid-forming. One survey found only 35% of CKD patients hit the target of a neutral or negative Potential Renal Acid Load (PRAL) score-even after counseling.

Patients who stuck with a plant-based diet for six months saw their bicarbonate levels rise by 3.5 mEq/L. That’s as good as medication. But it requires planning, support from a renal dietitian, and time. Many give up after a few weeks.

Who Gets Treated-and Who Doesn’t

Here’s the shocking part: only 43% of CKD patients with documented metabolic acidosis get alkali therapy. Why?

- Pill burden: Patients average 4.2 pills a day. That’s hard to remember.

- Taste: Liquid forms taste bad. 41% of patients quit because of it.

- Side effects: Bloating, nausea, and gas affect 29%.

- Missed diagnosis: Many doctors don’t check bicarbonate regularly. It’s not part of routine labs for early CKD.

- Disparities: Black patients are 9% less likely to get treatment than white patients. Rural patients are 14% less likely than urban ones.

Even when diagnosed, doctors are cautious. Some fear raising bicarbonate too high. A 2020 study found a U-shaped curve: lowest death risk at 24-26 mEq/L. Levels above 26 mEq/L were linked to higher mortality in elderly patients.

Current Guidelines and What’s Changing

KDIGO (Kidney Disease: Improving Global Outcomes) recommends starting alkali therapy when bicarbonate drops below 22 mEq/L. The goal? 23-29 mEq/L.

But the 2024 draft update is shifting that. New evidence shows even 22 mEq/L still protects the kidneys. So the new target range may be 22-29 mEq/L. That means more people qualify for treatment.

Doctors are also moving toward personalized targets:

• 24-26 mEq/L for patients with heart failure
• 22-24 mEq/L for frail, elderly, or malnourished patients
• Avoid potassium citrate unless serum potassium is below 4.5 mEq/L
• Limit calcium supplements to 1,000 mg elemental calcium per day

What Patients Are Saying

Online forums reveal real struggles:

> “Sodium bicarbonate made my blood pressure jump from 130/80 to 160/95 in two weeks. My nephrologist switched me to calcium citrate, but now I take six pills a day and still get leg cramps.” - CKDWarrior42, American Kidney Fund forum

> “The baking soda powder tastes awful. I have to mix it in orange juice. Now I’m drinking sugar I shouldn’t have.” - RenalRookie, Reddit

But there are wins too:

> “After six months of eating more veggies and less meat, my bicarbonate went up 3.5 mEq/L. No pills. No side effects.” - Patient, Cleveland Clinic

What’s Next?

The COMET-CKD trial, enrolling 1,200 patients, is testing high-dose vs. low-dose bicarbonate. Results are due in late 2025. If high doses show better kidney protection, dosing guidelines may change.

A new citrate-free alkali supplement (TRC001) is in early trials. It raised bicarbonate by 4.1 mEq/L in 12 weeks-with half the stomach upset of current options. If it works, it could be a game-changer.

The big picture? Correcting metabolic acidosis could prevent 28,000 cases of kidney failure each year in the U.S. alone. That’s $1.4 billion in savings. But it won’t happen unless doctors test bicarbonate routinely, patients get support to stick with treatment, and new, better options become available.

What You Can Do

If you have CKD:

• Ask your doctor to check your serum bicarbonate at least twice a year.
• If it’s below 22 mEq/L, ask about treatment options.
• Try adding 5-9 servings of fruits and vegetables daily. Swap one meat meal for beans or tofu.
• If you’re on sodium bicarbonate and have swelling or high blood pressure, talk to your doctor about alternatives.
• Don’t take potassium citrate unless your potassium is low. It’s risky in CKD.

Metabolic acidosis isn’t glamorous. It doesn’t make headlines. But it’s one of the most treatable drivers of kidney decline. Fix it, and you buy time-time to stay active, time to avoid dialysis, time to live better.