Testing for Hyperammonemia
Why, when, and how to test
Any unexplained change in consciousness, encephalopathy, or other neurological symptoms should prompt consideration of a plasma ammonia test.
This is important at any age, particularly in neonates whose clinical history does not match the severity of illness or whose illness remains unexplained.
Acute hyperammonemia can be life threatening.
Prompt plasma ammonia testing is critical when symptoms cannot otherwise be explained.
SAME TEST.
CHECK AMMONIA.
When Should Ammonia Be Checked?
Hyperammonemia may present in different ways across the lifespan. Unexplained neurological or behavioral changes should raise consideration of ammonia testing.
Altered Consciousness
Unexplained changes in alertness, responsiveness, or consciousness.
Encephalopathy
Acute or unexplained neurological deterioration or altered mental status.
Neurological Symptoms
Neurological symptoms that are unexplained or do not fit the expected clinical picture.
Unexplained Neonatal Illness
Especially when the clinical history does not match the severity of illness.
Proper Collection and Handling Matter
Problems with sampling, transport, and analysis can contribute to inaccurate results, including false positive plasma ammonia levels. Follow proper procedures when obtaining the sample.
Alert the Laboratory
Notify the laboratory of the incoming STAT ammonia order before the sample arrives.
Collect a Free Flowing Sample
Prepare to collect a free flowing venous or arterial blood sample. Do not use a tourniquet and keep the patient’s arm as relaxed as possible.
Use the Correct Specimen Tube
Collect the sample in a specimen tube, preferably prechilled, containing either lithium heparin or EDTA as an anticoagulant.
Transport and Analyze Immediately
Place the sample on ice. Order the sample to be handled STAT, transported to the laboratory, separated within 15 minutes of the draw, and analyzed immediately.
Call a Metabolic Geneticist
Call a metabolic geneticist immediately to evaluate signs or symptoms that may suggest an inborn error of metabolism.
Individual inborn errors of metabolism are rare, but collectively these disorders are common.
Do not wait for test results to call a metabolic geneticist.
Testing for Hyperammonemia: The Essentials
This downloadable brochure is designed for laboratory technicians, nurses, and other allied healthcare professionals.
It provides information about blood draw procedures, analysis of plasma ammonia results, and additional testing that may help differentiate among causes of hyperammonemia.
Download The Essentials PDFAge Dependent Ammonia Reference Levels
Normal age dependent blood ammonia reference levels currently displayed on CheckAmmonia.com are shown below.
Plasma Ammonia Testing Resources
Additional testing information and source references are available for healthcare professionals and families.
Plasma Ammonia Testing FAQ
Review frequently asked questions about plasma ammonia testing, possible causes of inaccurate results, and factors that may affect ammonia levels.
View FAQ →References
Review the published clinical literature and source materials supporting the Check Ammonia educational content.
View References →When symptoms do not make sense, Check Ammonia.
Explore additional clinical and awareness resources in the Check Ammonia Toolkit.