Last updated: October 8, 2014
Synonyms: anti-LKM antibody, microsomal antibody
CPT Code: 86376
Description: Anti–Liver-Kidney-Microsome (LKM) antibodies are a series of autoantibodies directed against enzymes in the endoplasmic reticulum of hepatocytes and other cells that are mainly associated with various liver diseases. Anti–LKM-1 antibodies bind to cytochrome P-450IID6 (CYP2D6). Although once considered to be restricted to patients with type 2 idiopathic autoimmune hepatitis (AIH), anti–LKM-1 antibodies have also been found in some patients with hepatitis C. Anti-LKM-2 antibodies bind to a distinct cytochrome P-450 enzyme and have been associated with hepatitis induced by some medications. Anti–LKM-3 antibodies bind to the enzyme UDP-glucuronosyltransferase and are associated with hepatitis D infection. Infection with hepatitis D occurs in approximately 5% of hepatitis B–infected persons and is associated with a worse prognosis.
Methods: Anti-LKM antibodies are measured using ELISA.
Indications: Anti–LKM-1 antibodies are used in the assessment of patients suspected of having AIH. Different subtypes of AIH are classified according to autoantibody reactivity. Type 1 AIH (the most common, constituting approximately 80% of AIH cases) is associated with antinuclear antibodies (ANAs) and anti–smooth muscle antibodies. Type 2 AIH, which often occurs in children, is characterized by anti–LKM-1 antibodies. Type 3 AIH is characterized by antibodies to soluble liver antigen (also known as liver-pancreas antigen).
Al-Khalodi JA, Czaka A. Current concepts in the diagnosis, pathogenesis, and treatment of autoimmune hepatitis. Mayo Clin Proc 2001;76:1237–1252.PMID: 11761505
Liberal R, Mieli-Vergani G, Vergani D. Clinical significance of autoantibodies in autoimmune hepatitis. J Autoimmun. 2013;46:17-24. PMID: 24016388