At a glance

Why get tested?
Testing is most commonly performed in children suspected of having an inborn error of metabolism
 
When to get tested?
Inborn errors of metabolism are inherited disorders resulting from a deficient enzyme or transport protein. The range of different pathways involved is very large and no one test can identify them all.  Organic acids are excreted in the urine and allow us to see problems in several pathways including those involving amino acids, fatty acids and neurotransmitters.  Symptoms range from relatively benign to severe presentations in the newborn period which may be fatal. Possible clinical presentations include, intellectual disability, seizures, tachypnoea, poor feeding, failure to thrive, vomiting, acidosis, coma.
 
Sample required?
Urine organic acids require a clean catch urine (minimum volume approximately 5ml)
 
Test preparation needed?
None
 

What is being tested?

All of the processes which take place in our cells are chemical reactions controlled by special proteins called enzymes.  If there is a change or mutation in the gene coding for an enzyme, the normal metabolism gets blocked. Because most metabolic processes involve acids, the block may cause the acids to build up body and may be toxic.  These acids appear in the urine and organic acid testing separates and identifies any changes which may indicate an inborn error of metabolism.
 
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
 

The Test

How is it used?

Organic acid testing allows us to identify if any particular acid is high or an abnormal compound is present which may indicate a problem in the enzymes used to breakdown the compound.  Depending on the natural history of the disorder, symptoms may be minimised or prevented by early diagnosis and treatment. Treatment may be based on dietary restrictions and/or supplementation with cofactors (e.g., riboflavin or cobalamin) or conjugating agents (e.g., carnitine or sodium benzoate).
 

When is it requested?

Testing is most commonly performed in children suspected of having an inborn error of metabolism. Symptoms may be present shortly after birth or may only become apparent when the child has a viral illness and does not eat normally for a few days.  Because organic acid testing can show problems in many different pathways it is often a first line test for investigating developmental delay or seizures.
 

What does the test result mean?

The laboratory will interpret the report and suggest any further testing which may be required.  Patients identified with an inborn error of metabolism are usually managed by specialist doctors in major centres.  A normal organic acid test does not rule out other inborn errors of metabolism.
 

Common Questions

Is organic acid testing covered by Medicare?

There is no Medicare rebate for organic acid testing.  It is a complex test only performed in a few labs in Australia. 
 

Last Review Date: March 1, 2018