Ammonia Indications :
An ammonia test is done for the following reasons -
1. To assess liver function when symptoms such as confusion, behavioral changes, excessive sleepiness, coma, or hand tremor are present
2. To evaluate the impact of treatment for liver diseases
3. To achieve prognosis for acute liver failure
4. To check ammonia levels in a person receiving nutrition intravenously
5. To diagnose Reye syndrome in a newborn. Reye syndrome is a childhood condition that damages liver and brain.
A blood sample may be taken intravenously to carry out the test. Do not smoke, eat or drink anything (other than water) for 8 hours prior to doing the ammonia test. Also, avoid heavy exercise before the test. Although some doctors believe that arterial blood can also be used for the test, there is no wide-spread consensus on this.
Ammonia is produced when the protein in our diet is broken down in the intestines. This process takes place with the help of digestion-aiding bacteria. Normally, the ammonia produce is converted into urea in the liver, which is then eliminated from the body through urine. However this process is impaired in those with liver conditions such as severe hepatitis and cirrhosis, causing the ammonia levels to rise.
Ammonia tests are carried out to evaluate the levels of ammonia in the blood.
Normal Range :
If the levels of ammonia are higher than normal it indicates that ammonia is not metabolized and eliminated effectively. Causes include –
· Reye’s syndrome (usually diagnosed in children)
· Liver /kidney damage (children and adults)
· Enzymatic defect in urea cycle
· Hepatic encephalopathy
· Gastrointestinal bleeding – here blood cells lyze to release protein and this is seen as increased ammonia levels in blood
· Muscle exertion produces more ammonia in blood
· Use of certain medications and drugs including diuretics, barbiturates, valproic acid, and narcotics
· Smoking and alcohol consumption.
If the levels of ammonia are lower than normal it indicates the following –
· Certain types of hypertension
· Usage of certain antibiotics such as neomycin