Definition of Ammonium ion:

The ammonium - blood test measures the amount of ammonia in a blood sample.

How the test is performed:

A blood sample is needed. For information on how this is done, see: Venipuncture

How to prepare for the test:

Fast for 8 - 12 hours. The health care provider may recommend that you stop taking drugs that may affect your test results.

Drugs that can falsely raise the blood amminia level include alcohol, acetazolamide, narcotics, and valproic acid. A high-protein diet can also raise the blood ammonia level. Talk to your health care provider before this test if you are taking any of these medications.

How the test will feel:

When the needle is inserted to draw blood, you may feel moderate pain, or only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the test is performed:

This test may be done if you have or are thought to have a condition that may cause a toxic buildup of ammonia. It is most commonly used to diagnose and monitor hepatic encephalopathy, a severe liver disease.

Ammonia (NH3) is produced by cells throughout the body, especially the intestines, liver, and kidneys. Most of the ammonia produced in the body is used by the liver to produce urea. Urea is also a waste product, but it is much less toxic than ammonia.

Ammonia is especially toxic to the brain. It can cause confusion, lethargy, and sometimes coma.