|Values are valid only on day of printing.|
Evaluation of patients with liver disease of unknown etiology
Evaluation of patients with suspected autoimmune hepatitis
Autoimmune liver disease (eg, autoimmune hepatitis and primary biliary cirrhosis) is characterized by the presence of autoantibodies including smooth muscle antibodies (SMA), antimitochondrial antibodies (AMA), and anti-liver/kidney microsomal antibodies type 1 (anti-LKM-1).(1) Subtypes of autoimmune hepatitis (AIH) are based on autoantibody reactivity patterns.
Anti-LKM-1 antibodies serve as a serologic marker for AIH type 2 and typically occur in the absence of SMA and antinuclear antibodies. These antibodies react with a short linear sequence of the recombinant antigen cytochrome monooxygenase P450 2D6.(2) Patients with AIH type 2 more often tend to be young, female, and have severe disease that responds well to immunosuppressive therapy.
< or =20.0 Units (negative)
20.1-24.9 Units (equivocal)
> or =25.0 Units (positive)
Reference values apply to all ages.
Seropositivity for anti-LKM-1 antibodies is consistent with a diagnosis of AIH type 2.
Serologic tests for autoantibodies, including anti-LKM-1, should not be relied upon exclusively to determine the etiology or prognosis of patients with liver disease.
Anti-LKM-1 antibodies may occur in some patients with chronic hepatitis caused by hepatitis C virus infection. Although the epitopes recognized by anti-LKM-1 antibodies in hepatitis C virus infection are different than in patients with AIH type 2, physicians must use caution in interpreting the results of tests for anti-LKM-1 antibodies in such patients.
1. Clinical Immunology Principles and Practice. Third edition. Edited by RR Rich, TA Fliesher, WT Shearer, et al: Philadelphia, PA, Mosby Elsevier, 2008
2. Czaja AJ, Homburger HA: Autoantibodies in liver disease. Gastroenterology. January 2001;120(1):239-249