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Antibodies to liver and kidney microsomal antigen in blood
Medical expert of the article
Last reviewed: 05.07.2025
Normally, the concentration of antibodies to liver and kidney microsomal antigen in the blood serum is less than 20 IU/ml; 20-25 IU/ml are borderline values.
Antibodies to liver and kidney microsomal antigen (LKM) are a heterogeneous group of autoantibodies divided into three subtypes based on their target Ags. The cytochrome P-450IID6 component with a molecular weight of 50,000 has been identified as the major antigen of LKM type I (LKM-1), LKM-2 are directed to cytochrome P-450IIС9 and have been detected in patients taking ticrinafen (a diuretic, currently not used), LKM-3 have been detected in the serum of patients with chronic viral hepatitis D (detected in 5-13% of cases), but the antigen for them has not yet been identified. They may be present in patients with autoimmune hepatitis type II (in 10% of patients).
The determination of antibodies to liver and kidney microsomes (LKM-1) is based on the ELISA method. This study is an addition to existing methods for diagnosing autoimmune hepatitis.
There are 4 types of autoimmune hepatitis. However, such division of chronic autoimmune hepatitis does not have much clinical significance in terms of treatment tactics, since the majority of patients, regardless of the type of disease, have effective immunosuppressive therapy.
The diagnosis of chronic autoimmune hepatitis is considered to be definitely established if:
- in the blood serum, titers of antinuclear antibodies, antibodies to smooth muscles, antibodies to microsomal antigen of the liver and kidneys are increased (more than 1:80);
- the concentration of IgG in the blood serum exceeds the upper limit of normal by 1.5 times.
- there is no history of taking hepatoxic drugs or alcohol abuse;
- There are no markers of viral hepatitis.
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