High Acid Levels In Blood Worsen Kidney Function

Too acidic blood will accelerate the decline in your kidney function

Maarten Takens (Flickr); Creative Commons 2.0

Our body's normal metabolism generates multiple waste products.  One of this waste product is acid.  An important source of acid in the blood is the breakdown of protein that we eat.  Proteins are made of building blocks called amino acids, some of which are rich in sulfur.  Once your body has utilized the protein it needs, the excess waste is converted into acid, specifically sulfuric acid (this is because some amino acids are rich in sulfur).

Living organisms require a tight balance between their acid and alkali levels to continue normal metabolism that is compatible with life  

This balance between acid and alkali is expressed in a unit called the "pH" (if you must know, pH is the negative log of hydrogen ion activity). In simple English, the pH is an indicator of the strength of acid/alkali in any aqueous solution.  Pure water has a pH of 7 (the lower the pH, the stronger the acid).  Our bodies have a pH range of around 7.3-7.4..

Since acid production is continuous, our body needs a mechanism to either get rid of the excess acid or to neutralize it. Organs that help get rid of this excess acid include the lungs and your kidneys. The kidneys are also a major producer of "buffers" that neutralize this acid. 

Why is this important  

As you might imagine from the above, when patients have kidney disease, their ability to buffer excess acid goes down, and its levels increase in the blood.

 This has implications for your overall health, including the function of your kidneys. Lets take a look at the supporting evidence then.

(We usually don't measure the level of acid in your blood directly as part of routine tests.  However what we do measure is your alkali levels.  This is part of the usual chemistry panel that you might have seen your physician order.  If you have access to your blood work, look for a test that says "bicarbonate" or "carbon dioxide" or "CO2".  This is a measure of the alkali in your blood).

Over the past few years, we have increasing evidence that abnormal levels of bicarbonate are associated with a higher risk of death (patients with bicarbonate levels <22 mmol/L have a multivariable-adjusted hazard ratio of 1.3 of death, as compared to patients with bicarbonate levels >22). 

Abnormal bicarbonate level has not just been linked to an increase risk of death. If you have kidney disease, low bicarbonate levels are likely to accelerate the decline in your kidney function. As per this study published in the American Journal of kidney disease in 2009, the hazard ratio for worsening of your kidney disease after adjustment for potential confounders was 1.54 for patients with bicarbonate levels ≤22 mEq/L. 

A Chicken and egg problem 

Notice that the above studies mention the word "associated".  In other words, we are not sure if abnormal bicarbonate levels have a causative role in either increasing the risk of death or in accelerating the decline in kidney function.  Association is not synonymous with causality.


So we still don't know if it is an independent factor that might be creating abnormal bicarbonate levels and therefore increasing the risk of death.  It could also be possible that patients with worse kidney disease will tend to have low bicarbonate levels because of the kidneys' reduced ability to buffer high acid levels.  In that situation, it is hard to tell whether the bicarbonate level in the blood just happens to be an innocent bystander which is just a part of the package for the sicker patient. 

So is this clinically relevant, actionable information 

Perhaps.  Given the strong association noted above, some physicians have advocated doing the intuitive thing.  Which is increasing the amount of alkali in your diet, or via supplementation.  This is done using medications, food supplements including sodium bicarbonate commonly known as baking soda, or dietary alterations. The last option is receiving a lot of attention lately, and kidney-friendly diets now heavily focus on reducing the acid producing content in the food

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