What is an Anti-LKM antibody test?
The Anti-LKM antibody (Anti-LKM Ab) test is a blood test that detects autoantibodies against liver-kidney microsomal (LKM) antigens.
Anti-LKM antibodies are most strongly associated with autoimmune hepatitis type 2 (AIH-2), a form of autoimmune liver disease in which the immune system mistakenly attacks liver cells.
The most clinically important type is Anti-LKM-1, which targets an enzyme called cytochrome P450 2D6 (CYP2D6).
What is the Anti-LKM antibody test used for?
The test may be used to:
Support the diagnosis of autoimmune hepatitis
Help identify type 2 autoimmune hepatitis
Investigate unexplained elevation of liver enzymes
Evaluate suspected autoimmune liver disease
Help characterize the autoimmune antibody profile in patients with liver inflammation
Anti-LKM antibodies are commonly interpreted together with other autoimmune liver markers, including:
ANA – antinuclear antibodies
SMA/ASMA – smooth muscle antibodies
Anti-LC1 – liver cytosol type 1 antibody
Anti-SLA/LP – soluble liver antigen/liver-pancreas antibodies
AMA – antimitochondrial antibodies
Total IgG
Why do I need an Anti-LKM antibody test?
Your healthcare provider may request this test if you have findings that could suggest autoimmune hepatitis, such as:
Persistently elevated ALT or AST
Unexplained liver inflammation
Elevated total IgG
Jaundice
Fatigue
Abdominal discomfort
Abnormal liver function tests
Suspected autoimmune liver disease
Anti-LKM testing can be particularly useful when evaluating suspected type 2 autoimmune hepatitis, especially in younger patients.
What happens during the test?
A small blood sample is collected from a vein in your arm.
The serum is analyzed using an immunological method to detect Anti-LKM antibodies.
Depending on the laboratory method, results may be reported as:
Positive/Negative
Detected/Not detected
An antibody titer or numerical antibody value
The laboratory's specific reference range and cutoff should be used when interpreting the result.
Will I need to do anything to prepare?
Usually, no fasting or special preparation is required.
Tell your healthcare provider about any known liver disease, autoimmune conditions, medications, and previous liver or autoimmune laboratory results.
Are there any risks?
The test involves a routine blood collection. You may experience minor discomfort, bruising, or tenderness at the collection site.
Serious complications are very uncommon.
What do the results mean?
Positive result
A positive Anti-LKM result means that antibodies against liver-kidney microsomal antigens were detected.
When accompanied by compatible clinical and laboratory findings, Anti-LKM-1 positivity provides important supportive evidence for autoimmune hepatitis type 2.
However, a positive result does not by itself establish the diagnosis.
Further evaluation may include:
ALT and AST
Bilirubin and other liver tests
Total IgG
ANA and SMA
Anti-LC1 and Anti-SLA/LP
Liver imaging when appropriate
Evaluation for viral and other causes of liver disease
Liver biopsy when clinically indicated
Negative result
A negative Anti-LKM result means that Anti-LKM antibodies were not detected by the assay.
This does not completely exclude autoimmune hepatitis.
Many patients with autoimmune hepatitis do not have Anti-LKM antibodies and may instead have other autoantibodies, such as ANA, SMA, Anti-LC1, or Anti-SLA/LP.
Therefore, a negative result should be interpreted together with liver enzymes, IgG, symptoms, and other diagnostic findings.
Important note about the results
Anti-LKM-1 is an important serological marker of autoimmune hepatitis type 2, but it should not be used as a stand-alone diagnostic test.
A positive Anti-LKM-1 result should be interpreted in the context of liver enzyme abnormalities, IgG levels, clinical findings, exclusion of other causes of liver disease, and other autoimmune markers.
Anti-LKM antibodies can occasionally be detected in other conditions, so a positive result does not automatically mean that autoimmune hepatitis is present.
The exact reporting format and positive cutoff depend on the assay method and manufacturer used by the laboratory. Results should therefore be interpreted according to the laboratory's validated reference criteria.
Prefer to talk to someone first? Contact us to book.
