EDTA ON ICE
NOTE Ammonia can significantly rise in stored plasma samples, getting the sample straight to the laboratory following collection is crucial.
Send on ice (min 0.5 ml)
Sick or premature – less than 150 umol/L
Neonate – less than 100 umol/L
Females 11 – 51 umol/L
Males 16 – 60 umol/L
Ammonia is produced in the gastrointestinal tract by the action of bacterial enzymes on proteins and amino acids. It enters the portal circulation and is normally metabolized in the liver to urea and glutamine. When the liver is unable to perform this function, increased amounts of ammonia enter the arterial circulation and diffuse across the blood-brain barrier. Helicobacter pylori in the stomach appear to be an important source of ammonia in patients with cirrhosis.
The use of ammonia for monitoring patients with hepatic encephalopathy is controversial. It is unlikely that ammonia is solely responsible for the encephalopathy of hepatic insufficiency. Plasma ammonia levels have usually been found to correlate poorly with the clinical stage of hepatic encephalopathy. A normal level does not rule out early stage hepatic encephalopathy. Measuring plasma ammonia may be useful in suggesting a hepatic origin for an encephalopathy of unknown origin. It is not useful in patients with known liver disease.
Elevated levels are also seen in:
Many factors can affect ammonia levels:
Cannot be added on to an existing request
Please note this test is not UKAS accreditedSpecimen Labelling Procedure