Liver autoantibodies (including anti-smooth muscle and -mitochondrial antibodies) play a central role in the diagnosis of autoimmune liver disease, including autoimmune hepatitis and primary biliary cholangitis. However, at low titres, these tests may be non-specific and result in an inappropriate testing and referral cascade.

Liver Function Test (LFT) derangements are often transient, so screening for secondary causes (including autoimmune liver disease) is usually not indicated in response to a single abnormal LFT result. Instead, further investigations should be considered only when the appropriate liver enzymes are persistently abnormal over at least two to three occasions during a period of monitoring. It is important to consider other more common causes of deranged liver enzymes (steatohepatitis, drug induced and viral hepatitis) based on a targeted clinical history, appropriate clinical features and other laboratory investigations. Further information on the investigation of persistently abnormal LFTs can be found on local HealthPathways.

Updated Testing Guidance

To support appropriate clinical use of testing and reduce unnecessary investigations, Awanui Laboratories will implement the following rule:

• Liver-related autoantibodies (including smooth muscle and antimitochondrial antibodies) will only be performed when there is evidence of abnormal liver enzymes.
• Testing will not be performed when liver function is normal or has not been assessed.

Clinical Justification

Many autoantibodies may be present well before the onset of clinically apparent disease, including autoimmune liver disease. While this may have relevance in research or disease prediction contexts, performing autoantibody testing in the absence of clinical or biochemical evidence of disease is not considered appropriate clinical practice. Unselected testing can lead to false-positive or non-specific results, potentially resulting in unnecessary follow-up investigations, patient anxiety, and inappropriate referrals.

This approach is intended to promote evidence-based practice and ensure that testing is targeted to patients most likely to benefit.

If you have any questions or wish to discuss specific cases, please do not hesitate to contact us.

Kind regards,

Richard Steele
Chief Medical Officer
Awanui Labs