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That’s Low –

Just when I wonder if I’m going to run out of topics to write about, I receive a reader’s request. This week, I was saved by a request to write about low anion gap. I know, I know, it sounds like we’re pioneers trekking our way across the mountains when you see that phrase out of context. So, let’s put it into context.

If you looked, you’d find the phrase included in the following blood tests according to the Cleveland Clinic:  

“The anion gap measurement is based on the results of individual electrolyte blood tests, which are commonly included in the following routine bloodwork panels:

Let’s do our usual backtracking a bit. My first stop was at Quest Health to find out what the CMP covers:

“This test is a useful tool containing routine screening tests that may help healthcare providers identify signs of certain medical conditions, such as kidney or liver disease, diabetes, hypertension, and other health conditions.



Total protein

Alanine aminotransferase

Aspartate aminotransferase

Alkaline phosphatase


Blood urea nitrogen



Carbon dioxide


Potassium and sodium”

Hmm, no mention of the anion gap here.

Let’s try a different site, MedlinePlus, to see what the BMP tests for:

“A basic metabolic panel (BMP) is a test that measures eight different substances in your blood. It provides important information about your body’s chemical balance and metabolism. Metabolism is the process of how the body uses food and energy. A BMP includes tests for the following:

  • Glucose, a type of sugar and your body’s main source of energy.
  • Calcium, one of the body’s most important minerals. Calcium is essential for proper functioning of your nerves, muscles, and heart.
  • Sodiumpotassiumcarbon dioxide, and chloride. These are electrolytes, electrically charged minerals that help control the amount of fluids and the balance of acids and bases in your body.
  • BUN (blood urea nitrogen) and creatinine, waste products removed from your blood by your kidneys.”

Again, no mention of the anion gap. Surely, the electrolyte panel will evaluate the anion gap. This time I turned to GoodRxHealth:

“An electrolyte panel (also referred to as a ‘metabolic panel’) measures electrolytes and other substances in the blood that play important roles in your overall health. These include:

  • Sodium (Na): plays a key role in fluid balance and brain function
  • Potassium (K): regulates the heartbeat as well as nerve and muscle activity
  • Chloride (Cl): contributes to fluid balance and acid-base levels in the blood
  • Carbon dioxide (CO2): indicates how well your body is maintaining the right acid-base balance
  • Blood urea nitrogen (BUN) and creatinine (Cr)two waste products that provide a measure of kidney function
  • Glucose: also known as ‘blood sugar’”

What! Again, no mention of anion gap. Although, you may have noticed lots of duplication for items measured among the tests. That is sort of helpful. But that’s it! I’m turning to my favorite dictionary of all time, the Merriam-Webster to see if I can find a definition for this elusive phrase. Uh-oh, nothing there. [Oh well, you can’t find everything there just because it’s my favorite.]

The University of Rochester Medical Center was much more to the point:

“Your blood contains sodium, chloride, and bicarbonate. All of these are charged particles. The value for the anion gap tells your healthcare provider something about which other charged particles must be in your blood to make it neutral.

This test gives clues about different types of acidosis, when your blood is too acidic. It also tells your provider about alkalosis, when your blood is not acidic enough. Acidosis and alkalosis can be life-threatening. It’s important to find the causes and treat them as soon as possible.”

Finally. Now we get to the good part. What does a low anion gap mean? WebMD to the rescue:

“If you really do have a low anion gap, it could mean your blood doesn’t have enough of a protein called albumin. Albumin helps important vitamins, hormones, and enzymes move throughout the body. Low albumin can be a sign of:

  • Kidney problems. Healthy kidneys block albumin from entering urine. When albumin is leaked into the urine, it may be a sign of kidney disease.
  • Heart disease. Heart disease, when treated with diuretics, may lead to alkalosis and low albumin.
  • Certain types of cancer Cancer may cause potassium levels in the blood to drop, causing alkalosis. Chemotherapy cancer treatments may also lead to lower potassium levels.
  • Liver disease. The acid—base balance in liver disease is complex. Your doctor may check look for respiratory alkalosis, metabolic acidosis, low albumin, and changes in your potassium levels.”

Wonderful, just wonderful. What are you supposed to do with that? Before you get upset, I ran across this very important warning on MedicalNewsToday:

“A low anion gap reading is very rare, and it often results from a laboratory error. As a result, a doctor who finds a low reading typically orders a second test.”

Add this information from Health Matters and I think we can start to make the connection between the kidneys and the anion gap:

“Our body chemistry consists of a never-ending cascade of molecules reacting with one another to make more complex molecules. A few are commonly familiar: sodium, potassium, and chloride. These can be further classified by their electrical charge. Sodium and potassium are positively charged and are referred to as cations; chloride is negatively charged and is referred to as an anion. An anion gap refers to the measured difference between cations and anions in serum, plasma, or urine….”

It seems low anion gap is very rare and could be due to lab error. If it’s confirmed, your doctor will have to test more to determine what is causing this condition before they can treat it. Notice kidney disease can cause low anion gap as well as some medications can. This was all new to me. I certainly hope it was helpful to the reader requested the information.

I very much appreciate reader comments telling me how interesting they find the blogs. Just remember that I’m not a doctor. I’m learning right along with you.

Until week,

Keep living your life!