|Values are valid only on day of printing.|
Evaluation of patients with suspected autoimmune liver disease, specifically autoimmune hepatitis or primary biliary cirrhosis.
Evaluation of patients with liver disease of unknown etiology.
Autoimmune liver diseases result from damage to hepatocytes or cholangiocytes caused by an inflammatory immune reaction. Included within this disease group are autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC), and primary sclerosing cholangitis (PSC). In some cases, patients with these diseases may present asymptomatically, with increases in various liver enzymes being identified incidentally during an unrelated clinical evaluation. On the other end of the spectrum are patients who present with clinical evidence of liver disease, including fatigue, hepatomegaly, ascites, esophageal varices, and/or jaundice.
Diagnosis of an autoimmune liver disease first requires that other etiologies of liver injury, including viral, drug, and metabolic causes, be excluded. In some situations, a liver biopsy may be indicated. For those patients in whom an autoimmune liver disease is suspected, autoantibody serology testing may be considered. The Autoimmune Liver Disease Panel, S includes markers that may support a diagnosis of an autoimmune liver disease, specifically AIH or PBC. Unfortunately, there are no known autoantibodies specific for PSC that are useful as diagnostic markers.
Patients with AIH may be positive for smooth muscle antibodies (SMAs) and/or antinuclear antibodies (ANAs). The SMAs associated with AIH are generally specific for F-actin. SMAs have a specificity of 80% to 90% for AIH, although the sensitivity is only in the range of 70% to 80%. In contrast, ANAs, although relatively sensitive for AIH, lack specificity, being associated with a variety of autoimmune diseases. Both SMA and ANA, along with other lab markers and biopsy evaluation, are included in the international diagnostic criteria for AIH.
Anti-mitochondrial antibodies (AMAs) are a diagnostic marker for PBC. AMAs are found in >90% of patients with PBC, with a specificity of >95%. AMAs are included in the diagnostic criteria for PBC, which was developed through an international collaborative effort.
SMOOTH MUSCLE ANTIBODIES
If positive, results are titered.
Reference values apply to all ages
MITOCHONDRIAL ANTIBODIES (M2)
Negative: <0.1 Units
Borderline: 0.1-0.3 Units
Weakly positive: 0.4-0.9 Units
Positive: > or =1.0 Units
Reference values apply to all ages.
ANTINUCLEAR ANTIBODIES (ANA2)
Negative: < or =1.0 Units
Weakly positive: 1.1-2.9 Units
Positive: 3.0-5.9 Units
Strongly positive: > or =6.0 Units
Reference values apply to all ages.
The presence of smooth muscle antibodies (SMAs) and/or antinuclear antibodies (ANAs) is consistent with a diagnosis of chronic autoimmune hepatitis, in patients with clinical and/or laboratory evidence of hepatocellular damage.
The presence of anti-mitochondrial antibodies (AMAs) is consistent with a diagnosis of primary biliary cirrhosis, in patients with clinical and/or laboratory evidence of hepatobiliary damage.
The presence of smooth muscle antibodies (SMAs) may be found in patients with active hepatitis cause by alcohol or drug exposure.
The presence of antinuclear antibodies (ANAs) occurs in patients with a variety of systemic autoimmune diseases, including systemic lupus erythematosus, rheumatoid arthritis, Sjogren syndrome, and systemic sclerosis.
The presence of smooth muscle antibodies (SMAs), antinuclear antibodies (ANAs), and antimitochondrial antibodies (AMAs) should not be relied upon exclusively to diagnose an autoimmune liver disease. Correlation with clinical presentation and other laboratory parameters of liver disease is required.
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2. Hennes EM, Zeniya M, Czaja AJ, et al: Simplified criteria for the diagnosis of autoimmune hepatitis. Hepatol 2008;48:169-176
3. Muratori L, Granito A, Muratori P, et al: Antinitochondrial antibodies and other antibodies in primary biliary cirrhosis: Diagnostic and prognostic value. Clin Liver Dis 2008;12:261-276
4. Karlsen TH, Schrumpf E, Boberg KM: Update on primary sclerosing cholangitis. Dig Liver Dis 2010;42:390-400