Summary

Amino acid testing is most commonly used to investigate children suspected of having an inborn error of amino acid metabolism, a condition known as aminoacidopathy. This is a rare but treatable condition that affects the body’s metabolism – the way it processes food for energy. 

Why get tested?

Aminoacidopathies are inherited disorders in which an enzyme or transport protein responsible for the breakdown of food is not working properly. This is caused by a mutation in the gene responsible for the particular amino acid.  Amino acids build up in the body and this can have an impact on normal growth and development.  More than 30 aminoacidopathies have been described in medical literature with symptoms ranging from relatively benign to severe.

Most metabolic disorders present early in life although milder forms can go undetected until adulthood.  

Plasma or urine amino acid testing separates and measures all the amino acids that are made by the body or taken in from the diet.  This makes it possible to see if any particular amino acid concentration is high or low which may indicate a problem in the enzymes used to make or break down the amino acid.

With early diagnosis and treatment symptoms can be minimised or prevented. Treatment may be based on dietary restrictions and/or supplements such as riboflavin or cobalamin or other substances such as carnitine or sodium benzoate.

Regular testing is used to help monitor treatment to make sure amino acid levels remain under control and nutrition is adequate for growth and development.

Having the test

Sample

Either blood or urine depending on the test.

Any preparation?

None.

Reading your test report

Your results will be presented along with those of your other tests on the same form.  You will see separate columns or lines for each of these tests.  

Increased or decreased levels of certain amino acids will point to different possible aminoacidopathies.  For example, increased glutamine may point to a defect in the urea cycle. The laboratory performing the test will comment on any important findings.

Having normal concentrations of amino acids does not rule out other inborn errors of metabolism.

Reference Intervals

Your results will be compared to reference intervals (sometimes called a normal range).

• Reference intervals are the range of results expected in healthy people. 
• When compared against them your results may be flagged high or low if they sit outside this range.
• Many reference intervals vary between labs so only those that are standardised or harmonised across most laboratories are given on this website.

If your results are flagged as high or low this does not necessarily mean that anything is wrong. It depends on your personal situation. Your results need to be interpreted by your doctor.

Questions to ask your doctor

The choice of tests your doctor makes will be based on your medical history and symptoms.   It is important that you tell them everything you think might help.

You play a central role in making sure your test results are accurate. Do everything you can to make sure the information you provide is correct and follow instructions closely.

Talk to your doctor about any medications you are taking. Find out if you need to fast or stop any particular foods or supplements. These may affect your results. Ask:

• Why does this test need to be done?
• Do I need to prepare (such as fast or avoid medications) for the sample collection?
• Will an abnormal result mean I need further tests?
• How could it change the course of my care?
• What will happen next, after the test?

More information

Pathology and diagnostic imaging reports can be added to your My Health Record. You and your healthcare provider can now access your results whenever and wherever needed.

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