THEammoniémieis a test to measure the rate ofammonia in the blood.

Ammonia plays a role in pH maintenance but it is a toxic element which must be quickly transformed and eliminated. If it is present in excess (hyperammoniémie), it is particularly toxic to the brain and can cause confusion (psychiatric disorders), lethargy and sometimes even a coma.

Its synthesis takes place mainly in theintestine, but also at the renal and muscular level. Its detoxification takes place in the liver where it is transformed into urea, then it is eliminated in this form in the urine.

As this is a toxic compound, it is important to perform an ammonia assay when you suspect an increase in its concentration.

The doctor can prescribe its dosage:

• if he suspects a Hepatic insufficiency

• to find the causes of unconsciousness or a change in behavior

• to identify the causes of a coma (it is then prescribed along with other tests, such as blood sugar, liver and kidney function assessment, electrolytes)

• to monitor the effectiveness of treatment for hepatic encephalopathy (disturbance of mental activity, neuromuscular function and consciousness that occurs as a result of chronic or acute hepatic failure)

Note that the doctor may ask for ammonia in a newborn if he becomes irritable, vomits, or shows significant fatigue in the first days of his birth. This dosage is especially carried out in the event of hospitalization.

The determination of ammonia can be carried out in different ways:

• by arterial blood sample, performed in the femoral artery (in the crease of the groin) or the radial artery (in the wrist)

• by a venous blood sample, usually taken at the bend of the elbow, preferably on an empty stomach

Normal values ​​for ammonia in adults are between 10 and 50 µmoles / L (micromoles per liter) in arterial blood.

These values ​​vary depending on the sample but also on the laboratory performing the analysis. They are slightly lower in venous blood than in arterial blood. They can also vary by sex and are higher in newborns.

If the results indicate a high level of ammonia (hyperammonemia), it means that the body is not able to break it down enough and eliminate it. A high rate can be associated in particular with:

• liver failure

• liver or kidney damage

• hypokalaemia (low level of potassium in the blood)

• heart failure

• gastrointestinal bleeding

• a genetic disease affecting certain components of the urea cycle

• severe muscle strain
• poisoning (antiepileptic medication or phalloid amanitis)

A low-protein diet (low in meat and protein) and treatments (arginine, citrulline) helping to eliminate ammonia may be prescribed.