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Saturday, March 9, 2019

Too Much Acid in My Body and CKD. What Should I Do?

The chemical formula for sodium bicarbonate.
If you have chronic kidney disease (CKD) you are at risk for having too much acid in your body. One of the functions of the kidneys is to remove that acid. When the kidneys don't work as well as they should they have trouble doing their job. Nephrologists order a laboratory test called the serum bicarbonate (chemical formula shown in the figure above) as a way to assess the amount of acid you have in your body.  The goal serum bicarbonate (also called serum bicarb) range for patients is 23 to 29. For the most part, when a patient has a level lower than 23, we say that person has a condition called "metabolic acidosis," and "base" therapy may be given to neutralize excess acid in the body.

Usually sodium bicarbonate is the medication recommended to neutralize the acid and raise the blood level bicarbonate to the normal range. The concern many doctors have with this approach is that the therapy, sodium bicarbonate, has sodium in it, and might raise a patient's blood pressure to an abnormal range. Sodium is also associated with swelling. During my training, years ago, many nephrologists were reluctant to offer sodium bicarbonate as a treatment. That said, there has been a paradigm shift in our thinking with respect to administering this therapy. Let me explain why starting with the risks and then discussing the benefits of sodium bicarbonate therapy.

Sodium bicarbonate (chemical formula, NaHCO3) is different than sodium chloride (also known as table salt or sea salt, chemical formula, NaCl). The two chemicals are different molecules. Sodium bicarbonate use, when compared with sea salt, results is less edema (fluid retention) and not as much high blood pressure. Doctors in the past just focused on the "sodium" part and didn't appreciate that the molecules are different. There usually is less risk of side effects with the use of sodium bicarb.

Now let's discuss the benefits of sodium bicarbonate use in the setting of chronic kidney disease. When compared with no treatment, the use of alkali therapy (that is sodium bicarb) slows the progression of chronic kidney disease. If you are at risk of progressing to end stage kidney disease over the next 5 years, the use of sodium bicarbonate might delay your starting kidney dialysis. The suggested benefit appears to be 3 percent less decline of function per year compared with no therapy. That is a significant difference!

[Read more: Michael Aaronson, MD Nebraska Nephrologist blog post: What is the Risk of My Kidneys Failing Over the Next 5 Years? Should I be Concerned?]

It should be noted that patients who receive bicarbonate can develop swelling and suffer from elevated blood pressure. With expectant management (preparing for this possibility and addressing the effects proactively), the side effects of bicarb can be dealt with. I would suggest having a nephrologist involved in your care if it is recommended that bicarb be added to your medical regimen -- especially if you have edema (swelling in the legs), existing hypertension, and/or heart failure. Nephrologists, as part of your care team, can help keep you out of trouble.

Sometimes providers will offer the patients they serve sodium citrate instead of sodium bicarbonate. Citrate is converted to bicarbonate in the body. So these two medications are basically equivalent. Other ways to treat acidosis include calcium carbonate, calcium citrate, or calcium acetate. Sometimes patients with chronic kidney disease have too much calcium in their bodies, because they tend to be vitamin D deficient and need to take vitamin D. Vitamin D replacement encourages the absorption of calcium which leads to hypercalcemia. For these reasons the calcium-based approach to treating metabolic acidosis in chronic kidney disease is not as desirable as sodium bicarbonate. That said, the best approach depends on the particular situation. Ask your kidney specialist for advice.

Dr. Aaronson, are there other benefits to using sodium bicarbonate?

Yes. Too much acid in the body affects bone health. The acid eats away at the bone and can lead to osteoporosis. Bicarb can help prevent this from happening. Bicarb can also help with a common condition that occurs in chronic kidney disease patients called secondary hyperparathyroidism.

Some have also suggested that treating acidosis may improve the body's nutritional status by preventing the breakdown of muscle. Keeping the serum bicarbonate in the normal range, greater than 23, may improve the protein level in the body (measured by a test called the serum albumin) as well.

In conclusion, there has been a paradigm shift in the way nephrologists approach too much acid in the body when a patient has chronic kidney disease. If you have a serum bicarbonate level in the blood that is low, you may want to consult with a nephrologist to see if you would be a candidate for treatment.

Take baking soda instead of sodium bicarbonate tablets for acid in the blood? Really?
Yes you can do this. We teach you how.