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 quiet but dangerous condition that speeds up kidney damage, breaks down muscle, and weakens bones. In people with chronic kidney disease (CKD), especially stages 3 to 5, metabolic acidosis isn’t rare-it’s common. About 42% of those with stage 5 CKD have it. And yet, many never get treated.

What Is Metabolic Acidosis?

Metabolic acidosis happens when your blood becomes too acidic because your kidneys can’t remove enough acid or make enough bicarbonate to balance it. Normal blood bicarbonate levels sit between 22 and 29 mEq/L. When they drop below 22, you’re in metabolic acidosis. This isn’t just a lab number-it’s a signal that your body is under stress.

The kidneys normally get rid of acid through urine and rebuild bicarbonate to neutralize it. But when kidney function drops below 30%, this system starts to fail. Acid builds up. And over time, that acid eats away at your muscles, bones, and even your heart.

Why Bicarbonate Matters in CKD

Bicarbonate isn’t just a buffer-it’s a lifeline. When you take sodium bicarbonate (baking soda), it enters your bloodstream and neutralizes the excess acid. This simple act slows the decline of your kidney function.

A major 3-year study published in the Journal of the American Society of Nephrology showed that CKD patients taking oral sodium bicarbonate had a 5.9 mL/min/1.73m² slower decline in eGFR compared to those who didn’t. That’s like adding two years of healthy kidney function over three years. Other studies found that keeping bicarbonate above 22 mEq/L cuts the risk of needing dialysis by 23%.

The KDIGO guidelines now recommend starting bicarbonate therapy when levels fall below 22 mEq/L. Many doctors wait until it’s below 20. But evidence shows that even a small drop below 22 starts causing harm. The goal isn’t to push bicarbonate to 30-it’s to hold it between 23 and 29 mEq/L. Too high, and you risk complications. Too low, and your kidneys keep deteriorating.

The Sodium Problem

Here’s the catch: sodium bicarbonate comes with sodium. One 650mg tablet contains 7.6 mEq of bicarbonate-and 160mg of sodium. A full daily dose can mean over 1,000mg of sodium. For someone with high blood pressure or heart failure, that’s dangerous.

One study found that CKD patients with hypertension who took sodium bicarbonate had a 32% higher chance of being hospitalized for heart failure. That’s why many nephrologists avoid it in patients with fluid retention, swelling, or poor heart function. It’s a trade-off: protect your kidneys, but risk your heart.

That’s why alternatives exist.

Alternatives to Sodium Bicarbonate

Sodium citrate (Shohl’s solution) is a liquid form that’s easier to dose. But it tastes awful-many patients mix it with orange juice, adding sugar they shouldn’t have. One Reddit user said it felt like drinking battery acid.

Potassium citrate sounds ideal-it adds potassium instead of sodium. But in CKD, potassium builds up easily. About 18% of patients on potassium citrate develop dangerous hyperkalemia (potassium over 5.0 mEq/L). The National Kidney Foundation advises against it in stage 3b-5 CKD unless potassium is already low.

Calcium citrate is another option. It avoids sodium and potassium. But it can raise blood calcium levels and increase kidney stones. One study found a 27% higher rate of calcium stones in patients on long-term calcium supplements. And if you’re already taking vitamin D or calcium for bone health, you might be overdoing it.

There’s also veverimer, a pill that binds acid in the gut without being absorbed. It showed promise in early trials-raising bicarbonate by 4.3 mEq/L in 12 weeks. But its phase 3 trial failed in 2021. It didn’t meet the target for long-term bicarbonate improvement. The FDA didn’t approve it. Tricida Inc. is trying again with new data in 2024, but for now, it’s not an option.

Diet Can Help-If You Stick With It

Food plays a huge role. Some foods produce acid when broken down. Meat, cheese, and processed grains are acid-forming. Fruits and vegetables? They’re base-forming.

Here’s what the numbers say:

• Beef: +9.5 mEq acid per 100g
• Cheddar cheese: +8.0 mEq per 100g
• Apples: -2.2 mEq per 100g
• Broccoli: -2.8 mEq per 100g

Switching from a standard Western diet to one rich in fruits and vegetables can reduce your daily acid load by 40-60 mEq. That’s like taking a full tablet of bicarbonate every day-without the sodium.

A patient at Cleveland Clinic raised their bicarbonate by 3.5 mEq/L in six months just by replacing meat dinners with lentil bowls and leafy greens. But it’s hard. Most people don’t know which foods are acid-producing. And few have access to a renal dietitian.

Only 35% of CKD patients hit the target of a neutral or negative Potential Renal Acid Load (PRAL) score-even after counseling. Adherence is the biggest barrier.

What Patients Actually Experience

Real people don’t live by guidelines. They live with side effects, pill burdens, and bad tastes.

One patient on an online forum said: “I was taking six calcium citrate pills a day. My legs cramped. I couldn’t sleep.” Another said: “The baking soda powder made me bloated. I stopped after two weeks.”

A 2022 survey of 457 CKD patients found:

• 68% struggled with pill burden (average 4.2 tablets daily)
• 41% hated the taste of liquid alkali
• 29% had nausea or bloating

These aren’t just inconveniences-they’re reasons people stop treatment. And when they stop, their kidneys decline faster.

Who Gets Treated? Who Doesn’t?

Despite strong evidence, only 43% of CKD patients with metabolic acidosis get alkali therapy. And there’s a clear gap:

• Black patients: 38% treated
• White patients: 47% treated
• Rural patients: 35% treated
• Urban patients: 49% treated

This isn’t about access to care-it’s about awareness. Many primary care doctors don’t check bicarbonate levels. They check creatinine and eGFR. But bicarbonate? That’s a nephrologist’s test. And if you’re not seeing a kidney specialist, you might never know you’re in acidosis.

What Should You Do?

If you have CKD, here’s what to ask for:

1. Ask for your serum bicarbonate level at your next blood test.
2. If it’s below 22 mEq/L, ask if alkali therapy is right for you.
3. Discuss your blood pressure, heart health, and potassium levels before choosing a treatment.
4. Ask for a referral to a renal dietitian. Even one session can change your food choices.
5. Track your symptoms: swelling, fatigue, muscle cramps, nausea.

Start simple. Add two servings of vegetables to your lunch. Swap one meat meal for beans or tofu. See how you feel. Then talk to your doctor about whether a low-dose bicarbonate tablet might help.

The Future Is Personalized

The KDIGO 2024 draft guidelines are changing. Instead of one target for everyone, they’re moving toward personalized goals:

• 24-26 mEq/L for patients with heart failure
• 22-24 mEq/L for elderly or malnourished patients
• 23-29 mEq/L for most others

And new drugs are coming. A new citrate-free alkali supplement (TRC001) is in trials. Early results show it raises bicarbonate just as well as sodium citrate-but with half the stomach upset.

The goal isn’t to cure CKD. It’s to slow it down. And correcting metabolic acidosis might be one of the simplest, cheapest, and most effective ways to do it.

Right now, 28,000 cases of kidney failure each year in the U.S. could be prevented if everyone with low bicarbonate got treatment. But that only happens if patients know to ask-and doctors know to listen.