Anion Gap

Electrolytes are minerals that have an electrical charge when they are dissolved in water or body fluids. You get them from the foods you eat and the fluids you drink. You have electrolytes in your blood, urine, tissues, and other body fluids. They help control the acid-base balance of your blood. A few of your body's electrolytes that are often measured in your blood include sodium, chloride, potassium, and bicarbonate.

Some electrolytes have a positive electric charge. Others have a negative electric charge. The anion gap measures the difference—or gap—between the negatively charged and positively charged electrolytes in your blood. If the anion gap is too high, your blood is more acidic than normal. If the anion gap is too low, your blood isn't acidic enough. Both high and low results may be signs of a serious disorder that needs attention.

Normal results may vary by lab. Your anion gap results may be based on the results of an electrolyte panel, a basic metabolic panel (BMP), a comprehensive metabolic panel (CMP), or a renal function panel (RFP).

Several types of medical conditions can cause abnormal anion gap test results. Your provider will use the results of this test, your medical history, and other tests to make a diagnosis.

A high anion gap test result may mean that you have acidosis. A low anion gap test result may mean you have alkalosis, but this result is so rare that your provider will usually have you tested again to make sure the results are accurate.