Liver kidney microsome type-1 (anti-LKM-1) antibodies are autoantibodies, proteins produced by the body's immune system that recognizes and targets its enzyme called cytochrome P450 (CYP2D6), a protein found primarily in liver cells. The development of anti-LKM-1 antibodies is strongly associated with type 2 autoimmune hepatitis. This test detects and measures the amount (titer) of anti-LKM-1 (or antibody against CYP2D6) in the blood.
Autoimmune hepatitis is an acute or chronic inflammation of the liver that can lead to liver cirrhosis and, in some cases, to liver failure. It is hepatitis that is not due to another identifiable cause, such as a viral infection, exposure to a drug or toxin, a hereditary disorder or alcohol abuse. Anyone can develop the disorder, but the majority of those affected are women.
A high amount or titer of anti-LKM-1 indicates that it is likely that the person tested has type 2 autoimmune hepatitis, but the result is not definitive. A liver biopsy may be performed to evaluate liver tissue for damage and scarring to help confirm the diagnosis.
If the anti-LKM-1 test is negative, but SMA and/or ANA are positive, then the person likely has type 1 autoimmune hepatitis.
If both are negative, then the person's symptoms are likely due to a cause other than autoimmune hepatitis. However, the condition is not entirely ruled out. Not all people with autoimmune hepatitis will produce anti-LKM-1 or SMA antibodies; some people produce other autoantibodies that are rarely tested.
To help diagnose autoimmune hepatitis and distinguish it from other causes of liver injury