Organic acids - urine

Last updated: Monday, 22, March, 2004

MBS Online Search Page: Click here for details

Item Process
Specimen

Random urine, collected when patient is acidotic if the test is being done for identification of the cause of metabolic acidosis.
Freeze sample after collection.

Method

GCMS.

Application

Identification of the cause of metabolic acidosis with increased anion gap in an infant or child if an organic acidaemia is suspected.

Diagnosis of certain genetic diseases in which abnormal organic acids occur without metabolic acidosis.

Interpretation

In some diseases the abnormality is present only intermittently (eg, during metabolic acidosis).

The nature and relative amount of organic acids detected usually allows the complete identification of the type of organic acidaemia present and at least narrows it down to a relatively small group.

Abnormal organic acids are often seen in non-genetic lactic acidosis and ketoacidosis and careful interpretation is required.

In some rare disorders (eg, type I tyrosinaemia, Canavan disease) abnormal organic acids are present in the absence of metabolic acidosis - consult pathologist.

Reference

Chalmers RA. In: Holton BJ ed. The Inherited Metabolic Diseases. 2nd ed. Churchill Livingstone 1994.