Our Tests

CYP2C9 Screen

Also known as: 2C9

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Variants in the CYP2C9 genes modify the rate at which some medications are broken down. The drugs affected include

  • tricyclic antidepressants

A patient with such variants may be at risk of toxicity from the medication.

When considering antidepressant therapy, this test is often combined with analysis of the CYP2C19 and CYP2D6 genes.

When considering warfarin therapy, this test is often combined with analysis of VKORC1.

This test has a role in identifying patients who may benefit from avoiding a specific drug or dose, but it provides little useful information for people (including relatives) who are not taking the medications of concern. Testing of relatives is generally not recommended.

Clinical Utility

The laboratory report describes the gene variants detected in a patient, and the implications regarding drug choice or dose.



Test Method

Analysis of the CYP2C9 gene.

Test Ordering

This test can be requested by any medical practitioner.

5 mL blood in EDTA. Specimens may be collected by the requesting practitioner or at any Sonic Healthcare pathology collection centre.

To help ensure the quality of the test, a genetic test should be done with a dedicated sample whenever possible i.e. a sample collected specifically for that test rather than a sample that is used for multiple tests.

We also recommend that the patient or another adult check the labelling of request forms and sample tubes.

Special Instructions

Please list current and proposed medications on the request form. Please highlight any medications that have caused problems in the past.



There is a reduced fee for a combined test of CYP2C9, CYP2C19, and CYP2D6. Please contact the laboratory on 1800 010 447.

Medicare Rebate

This test is not rebated by Medicare. The laboratory assumes that the patient or client has provided informed financial consent for the test.

Turnaround Time

10 working days.