Ammonia Levels
Reviewed
An ammonia levels test measures the amount of ammonia in a sample of your blood. Ammonia is a normal waste product. Normally, your liver changes ammonia into urea, which your kidneys get rid of in urine. High ammonia levels can be toxic to your brain. This test may be used to help diagnose high ammonia levels in people who have symptoms, but it alone cannot diagnose conditions that increase ammonia. It may be used with other tests to help find the cause. It is also used to monitor conditions that cause high ammonia levels and to check if treatment is working.
Preparation and collection
Your provider will give you specific instructions. You should not smoke for several hours before the test. You may be asked to avoid strenuous exercise and alcohol for a period of time. You may also need to fast (not eat or drink) for several hours. Your provider may tell you to stop taking certain medicines, including diuretics (water pills) and opioid pain medicines. But never stop taking any prescription medicines without talking with your provider first. Babies do not need any special preparations before the test.
Understanding this test
Use the reference interval and units printed by the laboratory that performed the test. A result outside that interval is not a diagnosis by itself, and a result inside it does not rule out every condition. Your symptoms, history, medicines, timing, and related tests can change what the result means.
- The test alone cannot diagnose conditions that increase the amount of ammonia in your blood.
- There is very little risk to having a blood test; you may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
- If your blood sample was taken from an artery, you may also have some bleeding where the needle was put in. Very rarely, the needle may damage a nerve or the artery.
What to do next
If your test results show ammonia levels that are higher than normal, more tests will usually be done to diagnose the cause. Treatment will depend on the condition that's causing the problem. If you have questions about your test results or treatment, talk with your provider.