The short answer: Metabolic acidosis can develop in chronic kidney disease (CKD) because damaged kidneys become less able to remove acid and maintain the body’s normal bicarbonate level. Sodium bicarbonate, commonly called baking soda, can raise blood bicarbonate in some people with CKD. However, it is not a universal treatment, and taking ordinary baking soda without medical guidance can cause problems, particularly because it adds sodium.
What is metabolic acidosis?
Your body constantly produces acid as cells use nutrients for energy. Healthy kidneys help maintain the correct acid-base balance by:
- Removing acid into the urine
- Reclaiming bicarbonate
- Producing new bicarbonate when needed
Bicarbonate is one of the body’s main buffers. It helps neutralize acid and keep blood chemistry within a narrow range.
As CKD becomes more advanced, the kidneys may not remove enough acid. Bicarbonate can then fall, producing metabolic acidosis.
This does not mean that your blood suddenly becomes extremely acidic. Usually, the change is much smaller but can still matter when it persists.
How is it detected?
A routine blood chemistry panel often reports total CO₂, which mainly reflects bicarbonate in this context.
A persistently low bicarbonate or CO₂ result can suggest metabolic acidosis, but one low result does not automatically prove that CKD is causing it.
Doctors may consider:
- Previous bicarbonate/CO₂ results
- eGFR and other kidney tests
- Medications
- Recent illness
- Diarrhea or other causes of bicarbonate loss
- Electrolytes, particularly sodium and potassium
- The overall clinical situation
If the result is unexpected or borderline, it may need to be repeated or evaluated with additional testing.
Why does CKD cause acidosis?
The kidneys normally excrete acid generated by metabolism, especially acid associated with protein breakdown.
With declining kidney function, the kidneys have less capacity to handle this acid load.
There is also a more subtle problem: CKD can alter the way the kidneys process ammonium, an important pathway for getting acid safely into the urine.
The result can be a gradual tendency toward acid retention and lower bicarbonate.
Metabolic acidosis is more common in advanced CKD, but it does not occur in exactly the same way or at the same stage in everyone.
What symptoms can it cause?
Mild chronic metabolic acidosis may cause no obvious symptoms.
More significant acidosis can contribute to:
- Fatigue or weakness
- Loss of appetite
- Nausea
- Faster or deeper breathing when acidosis is severe
- Worsening overall illness
These symptoms are not specific to acidosis. For example, fatigue in someone with CKD may also result from anemia, poor sleep, medications, infection, thyroid problems, or other conditions.
So symptoms alone cannot tell you whether your bicarbonate is low.
Does low bicarbonate mean CKD is getting worse?
Not necessarily.
A persistently low bicarbonate level can occur with reduced kidney function and may be associated with CKD complications, but it should not be interpreted as a standalone measure of kidney disease progression.
For kidney function, trends in eGFR, creatinine, urine albumin, blood pressure, and the underlying kidney disease all matter.
A useful way to think about any abnormal bicarbonate result is:
Previous result → current result → size of change → time interval → clinical context
A single abnormal CO₂ value does not tell the whole story.
How does baking soda help?
Baking soda is sodium bicarbonate.
When prescribed for metabolic acidosis, sodium bicarbonate supplies bicarbonate that can help raise the bicarbonate concentration in the blood.
The goal is not to make the blood “alkaline.” It is to correct an abnormal acid-base balance.
Some clinical studies have found that alkali treatment can increase serum bicarbonate in people with CKD and metabolic acidosis. Whether treating mild acidosis improves long-term kidney outcomes for every patient remains an area of ongoing research.
Therefore, bicarbonate treatment should be based on the individual’s laboratory results and clinical situation rather than simply having CKD.
Why shouldn’t you start baking soda on your own?
The important issue is the sodium that comes with sodium bicarbonate.
Extra sodium can contribute to:
- Fluid retention
- Higher blood pressure
- Worsening swelling
- Greater difficulty controlling heart failure in susceptible people
This is particularly relevant to people with CKD who already have hypertension, edema, or heart disease.
Sodium bicarbonate can also interact with other aspects of a person’s treatment plan, so the appropriate dose and monitoring need to be individualized.
Do not use kitchen baking soda as a self-prescribed CKD treatment.
What about bicarbonate and potassium?
Acid-base balance and potassium are closely connected, but they should not be managed based on assumptions.
CKD can increase the risk of hyperkalemia, or high blood potassium, and several medications can also raise potassium.
Correcting metabolic acidosis may influence potassium in some circumstances, but sodium bicarbonate is not a substitute for proper evaluation and treatment of hyperkalemia.
A potassium result needs to be interpreted according to its actual level, symptoms, kidney function, medications, and whether the result is new or persistent.
Can diet help?
Diet can influence the body’s acid load, but this does not mean everyone with CKD should start following a highly alkaline diet.
A diet containing an appropriate amount of plant foods may reduce dietary acid production in some people, but potassium and phosphorus restrictions may be necessary for certain patients.
For example, someone with CKD and high potassium cannot simply increase high-potassium fruits and vegetables because they are considered “alkaline.”
Diet should therefore be matched to the person’s:
- Kidney function
- Blood potassium
- Blood phosphorus
- Blood pressure
- Diabetes status
- Overall nutritional needs
A renal diet is not one identical diet for everyone with CKD.
What should you do if your CO₂ or bicarbonate is low?
If a blood test shows low bicarbonate, ask your clinician:
- Is the result persistent or was it a one-time finding?
- Could something other than CKD be causing it?
- What are my potassium and kidney-function results?
- Do my medications affect acid-base balance?
- Would alkali treatment be appropriate for me?
If treatment is recommended, your clinician may monitor bicarbonate, sodium, potassium, blood pressure, fluid status, and kidney function over time.
When is acidosis urgent?
Severe metabolic acidosis can be a medical emergency, particularly when associated with another serious illness or acute kidney injury.
Seek urgent medical attention for symptoms such as severe breathing difficulty, confusion, fainting, profound weakness, persistent vomiting, or markedly reduced urine output, especially if you are already known to have significant kidney disease.
Bottom line
Metabolic acidosis in CKD occurs when the kidneys can no longer handle the body’s acid load effectively enough to maintain normal bicarbonate levels.
Sodium bicarbonate can raise bicarbonate and is an established treatment option for selected people with CKD and metabolic acidosis. But baking soda is not automatically appropriate for everyone with CKD, and its sodium content can be important for people with high blood pressure, swelling, or heart problems.
If your CO₂ or bicarbonate is low, the safest approach is to look at the trend, kidney function, potassium, medications, other possible causes, and your overall health before deciding whether treatment is needed.