Anion Gap Blood Test Test
The anion gap blood test checks the acid-base balance in your blood. It shows if your blood is too acidic or not acidic enough, and whether your electrolytes are out of balance.
What this test measures
The anion gap measures the difference between negatively charged and positively charged electrolytes in your blood. This helps determine your blood's acid-base balance (pH balance).
What your results mean
Reference ranges vary by laboratory and by your age and sex. MedlinePlus does not publish a single normal range for this test — always read your result against the range printed on your own lab report and discuss it with your provider.
Higher-than-normal results
A high anion gap test result may mean you have acidosis, which may be caused by dehydration, diarrhea, too much exercise, kidney diseases, diabetes or diabetic ketoacidosis, salicylate poisoning (e.g., from too much aspirin), or antifreeze poisoning.
Lower-than-normal results
A low anion gap test result may mean you have alkalosis, but this is rare. The most common cause is a low level of albumin, which may be a sign of not eating enough protein, kidney problems, liver disease, heart disease, or some types of cancer.
Frequently asked questions
What is an anion gap blood test?
It is a test that measures the acid-base balance in your blood by checking the difference between negatively and positively charged electrolytes.
What do electrolytes have to do with the anion gap?
Electrolytes are minerals that help control the acid-base balance of your blood. The anion gap measures the difference between negatively charged and positively charged electrolytes.
What does a high anion gap mean?
A high anion gap means your blood is more acidic than normal, which may be caused by conditions like dehydration, kidney disease, or diabetes.
What does a low anion gap mean?
A low anion gap means your blood is not acidic enough, but this is rare. It is often due to low albumin levels, which can be linked to various health issues.
How are anion gap results reported?
Normal results may vary by lab. Your provider will use the results along with your medical history and other tests to make a diagnosis.
Related lab tests
Sources
- MedlinePlus: Anion Gap Blood Test — NIH MedlinePlus
Last updated . Information is aggregated from official public sources and is not a substitute for professional medical care.