What Happens if You Have a Low Anion Gap?


Quick Answer

The most common cause of a low anion gap level is a lack of albumin protein in the blood, or hypoalbuminemia, when immunoglobulin levels are increased. Albumin is both a protein and an anion.

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Lab Testing Errors
In general, low anion gap levels are rare. It can be due to an error during the testing process. Unfortunately, the testing procedure means that low levels are wrongly reported a majority of the time. A study found that in the one percent of patients that received test results that indicated low anion gap levels, 90 percent of the results were due to an error during the calculation process. For this reason, it's not uncommon for doctors to order the test twice in order to ensure that the results are accurate.

Causes of Low Anion Gap Levels
Although there are several possibilities for low anion gap levels, some of the possibilities include something as simple as having diarrhea or exercising too much. Also, having kidney issues can cause low anion gap levels because there is too much acid in the urine.

Diseases that Cause Low Anion Gap Levels
On the other hand, if a subject has hypoalbuminemia, it also leads to low anion gap levels as well. Other possible causes of a low anion gap value include hyponatremia, which indicates a low level of sodium in the blood, or multiple myeloma, a form of cancer of the bone marrow.

Compounds that Cause Low Anion Gap Levels
If someone is taking certain medications, it can also lower their anion gap levels below the normal threshold. This includes certain drugs, both prescription and herbal, that include bromide. Too much bromide leads to chloride to be miscalculated, which then causes the anion gap levels to be miscalculated as well. Additionally, taking too much lithium can lower the anion gap level. Lithium is found in some prescription medications, including those for bipolar disorder.

Determining One's Anion Gap
The anion gap, also called AG or AGAP, is calculated using the results of an electrolyte panel and each lab may use their own specific calculation. It is calculated using arterial blood. A common method used to determine the anion gap is to add the number of chloride and bicarbonate anions and then subtract the amount from the total number of sodium and potassium cations. Another common method used by many hospitals is to subtract the total number of sodium and bicarbonate anions from the number of sodium cations only. As these methods illustrate, the anion gap is an estimated value. The normal range is considered to be between 8 and 16 mEq (or milliequivalents) per liter of blood.

This anion level testing can be ordered for people who are showing signs of an imbalanced blood acid level. For some people, these symptoms include throwing up, abnormal heartbeat and confusion. It's a simple blood test, so one only needs to prepare to have some blood drawn.

Fixing Anion Gap Levels
In order to fix one's anion gap levels, it's necessary to cure any diseases that may be causing the low levels. Also, changing medications to avoid bromide and lithium is also helpful.

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