Ammonia

Category:

Ammonia

Description

Ammonia is produced by digestion of protein. It is normally transported to the liver, where it is transformed into urea and glutamine. Urea is evacuated from the blood by means of the kidneys and finally excreted in the urine. If the decomposition of ammonia is incomplete it increases its concentration in the blood and passes through the blood/brain barrier causing severe problems such as hepatic encephalopathy, that leads to confusion, sleepiness, and eventually to coma and death.

Children with high ammonia levels vomit frequently, are irritable, and can be increasingly lethargic.

Its concentration is measured by means of analysis of a blood sample drawn from the vein in the arm. Ammonia tests on arterial blood are told to be more useful but there is no agreement on this respect.

Purpose of the test

To meassure concentration of Amonia in blood in order to detect several possible problems such as severe liver disease, renal failure, and others in patients who experiment changes in consciousness, severe liver problems and other symtoms.

Also help to detect  hepatic encephalopathy and Reye’s syndrome.

Reference range values

11 – 35 mcmol/L

Abnormal findings

High levels of amonia in infants can be caused by:

·        inherited urea cycle enzyme deficiency or defect.  

·        hemolytic disease of the newborn.

Also high ammonia levels and decreased glucose levels may indicate presence of Reye’s syndrome in symptomatic children and adolescents.

Both in children and adults, high levels of ammonia can also indicate liver or kidney damage.

High levels of amonia can also be caused by:

·        Gastrointestinal bleeding

·        Muscular exertion

·        Drugs : including  alcohol, barbiturates, diuretics, valproic acid, and narcotics

·        Smoking

Low levels of ammonia can be the result of:

·        hypertension

·        use of some antibiotics, such as neomycin