The anion gap blood test is a calculated value that comes from the results of an individual’s electrolyte panel. It is used to determine what a person’s anion and non-anion gap happens to be in regards to excess acid levels that may exist in the body. Called acidosis, too much acid can interfere with cell functioning and this may cause delays in treatment.
The anion gap is discovered through the measurement of positive ions compared to negative ions. It is usually taken from the serum, but some medical providers may prefer a urine test instead of a blood test to get this information.
It is important to note that the anion gap is considered a non-specific measurement. It increases when unmeasured anions increase, so a medical provider knows there is an issue, but doesn’t know what is causing the issue. Based on an individual’s physical symptoms, however, the test results from the electrolyte panel and the anion gap calculation can lead toward a diagnosis.
The anion gap blood test is typically ordered when someone is suffering from specific physical conditions. This may include confusion, edema, or a cardiac arrhythmia. It is also ordered when an illness occurs at regular intervals for an unknown cause. Sodium, potassium, and chloride are typically the most common results that are analyzed.
What Do My Test Results Mean?
Most people who have their anion gap calculated will have a normal result. A normal result may even occur if there is an electrolyte imbalance in place. Normal results are typically less than 11 mEq/L. Anything above 11 is considered a high test result, while anything below 3 will typically be considered a low test result, though the actual numbers may vary by laboratory and by patient.
If the test results are high, then treatment for the imbalance of the acid/base must begin. There may be several different causes of a high test result, so comparing symptoms to the test results becomes important. Uncontrolled diabetes is one of the most common reasons for higher than normal levels, but so is starvation. People who take large amounts of aspirin or are exposed to antifreeze and other chemicals may also have high test results.
In some instances, a high anion gap may occur because of high lactic acid levels or through alcohol abuse.
If the anion gap blood test comes back with a low test result, then this is an indication that albumin levels are lower than they should be. Immunoglobulins may also be increased. Low test results are extremely rare, however, and retesting usually occurs if this is the result because it is more likely that a lab error caused this result than a physical problem.
What About the Electrolyte Levels?
Having one single electrolyte fall outside of a normal range may be an error in the test results. One single out of range issue may require a second test to confirm. If confirmed and there is an acid/base imbalance, then blood gas tests are typically the next step in the diagnositc process. This will help to measure carbon dioxide and oxygen levels that are in the blood and give a doctor an idea of the pH level that someone has.
Here’s What You Need to Know
Treatments are based on the extent of electrolyte imbalance that has occurred. Many options involve lifestyle changes that include lower salt levels in foods, increasing fluid consumption, or using diuretics. Sometimes medication may be necessary to treat the anion gap blood test results as well.
Medications can also affect the test results. Certain over the counter medicines can temporarily increase sodium levels. Antidepressants can actually lower sodium levels. Antacids can affect chloride levels, while certain antibiotics may affect carbon dioxide levels in the blood to create physical symptoms related to the anion gap.
It is also important that a blood draw be processed properly in order for test results to be accurate. Potassium in particular is sensitive to how the sample is handled and transported. If there are delays in the processing of the sample or it is handled roughly, then potassium is able to leak out of the blood cells to create a false higher than normal result.
Knowing the anion gap can help medical providers begin to find a correct diagnosis for what may be bothersome physical symptoms. Having balanced electrolytes is important to good health. These test results can help to find deficiencies or indicate when too much of one electrolyte is being consumed so that the proper balance can be achieved.