Hepatitis Autoimmune Panel

This panel may be helpful in the diagnostic evaluation of individuals with suspected autoimmune hepatitis (AIH). This panel includes an antinuclear antibody (ANA) immunofluorescence assay (IFA) screen, performed on human epithelial type 2 (HEp-2) cells, with reflex to titer and pattern; actin (smooth muscle) antibody (SMA); liver kidney microsome type 1 (LKM-1) antibody (IgG); and anti-mitochondrial antibody (AMA) with reflex to titer.

The diagnosis of AIH is based on clinical features, serologic profile, and exclusion of resembling diseases such as viral hepatitis [1]. The detection of antibodies associated with AIH helps establish the diagnosis and differentiate AIH types. ANA and SMA are characteristic of type 1 AIH, while LKM-1 antibody is characteristic of type 2 AIH [2]. ANAs are detected in 75% of patients with type 1 AIH but are also common in many other autoimmune diseases [1]. SMAs are present in approximately 85% of patients with type 1 AIH but can be detected in a range of other conditions, such as viral hepatitis, malignancies, rheumatic diseases, and nonalcoholic fatty liver disease [1]. LKM-1 antibody is specific for type 2 AIH and usually is not concurrent with ANA and SMA.

Up to 20% of patients with AIH are negative for ANA, SMA, and LKM-1 antibody. In these patients, testing antibodies associated with AIH, such as AMA, may help support the diagnosis [2]. AMA is the serologic hallmark of primary biliary cholangitis (PBC) but can also be detected in PBC-AIH overlap syndrome and type 1 AIH [1].

The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings.

References
1. Neuberger J, et al, eds. Autoimmune Liver Disease: Management and Clinical Practice. 1st ed. John Wiley & Sons Ltd, 2020.
2. Mack CL, et al. Hepatology. 2020;72(2):671-722.