Actin Smooth Muscle Antibody IgG

What the laboratory says this test is for

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.References1. 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.

What the laboratory says this test is for

This panel may help diagnose or exclude autoimmune hepatitis (AIH) in patients with hepatitis C for the purpose of informing treatment options. 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; smooth muscle antibody (SMA); liver kidney microsome type 1 (LKM-1) antibody; soluble liver antigen (SLA) antibody; and anti-mitochondrial antibody (AMA) with reflex to titer.Certain hepatitis C therapies, such as peginterferon and ribavirin, are contraindicated for patients with AIH or other autoimmune conditions. The detection of certain antibodies associated with AIH may help establish or exclude the diagnosis. ANA and SMA are characteristic of type 1 AIH, while LKM-1 antibody is characteristic of type 2 AIH [1]. ANAs are detected in 75% of patients with type 1 AIH but are also common in many other autoimmune diseases [2]. 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 [2]. 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 other antibodies associated with AIH, such as AMA and SLA, may help assess the diagnosis [1]. AMA is the serologic hallmark of primary biliary cholangitis (PBC) but can also be detected in PBC-AIH overlap syndrome or type 1 AIH [2]. SLA antibody is highly specific (99%) for AIH and can be detected as a sole marker in 14% to 20% of patients [1]. The presence of SLA antibody is associated with the likelihood of severe disease and relapse after drug withdrawal [1]. Unlike ANA, SMA, and LKM-1, SLA is very rarely present in patients with hepatitis C [2].The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings.References1. Mack CL, et al. Hepatology. 2020;72(2):671-722.2. Neuberger J, et al, eds. Autoimmune Liver Disease: Management and Clinical Practice. 1st ed. John Wiley & Sons Ltd, 2020.

What the laboratory says this test is for

This panel may be helpful in the diagnostic evaluation of individuals with suspected primary biliary cholangitis (PBC). This panel includes anti-mitochondrial antibody (AMA), with reflex to titer; 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; IgG); Sjogren antibodies (SSA, SSB); thyroid peroxidase (TPO) antibody; and liver kidney microsome type 1 (LKM-1) antibody (IgG).PBC can be diagnosed by fulfilling 2 of the 3 diagnostic criteria that comprise biochemical evidence, histologic evidence, and the presence of PBC-specific antibodies [1]. Presence of AMAs is the serologic hallmark of PBC and can be detected in approximately 95% of patients. ANAs are detected in 10% to 30% of patients with PBC. The presence of certain ANAs patterns including those associated with antibodies to sp100 or gp210 have diagnostic value, especially in AMA-negative PBC [1, 2].Other antibodies included in this panel may aid in differential diagnosis or identify concomitant autoimmune diseases. Antibodies to SSA and SSB are associated with Sjogren syndrome, an autoimmune disease frequently diagnosed in patients with PBC [1]. SMAs are present in most patients with type 1 autoimmune hepatitis (AIH) but can be detected in a range of other conditions, such as viral hepatitis, malignancies, rheumatic diseases, and nonalcoholic fatty liver disease. LKM-1 antibody is characteristic for type 2 AIH in the absence of hepatitis C. TPO antibodies are associated with autoimmune thyroid disease, which is common in patients with PBC [2]. Note that the presence of these antibodies does not confirm the coexistence of associated autoimmune diseases [1].The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings.References1. Lindor KD, et al. Hepatology. 2019;69(1):394-419.2. Neuberger J, et al, eds. Autoimmune Liver Disease: Management and Clinical Practice. 1st ed. John Wiley & Sons Ltd, 2020

What the laboratory says this test is for

Actin is the major antigen to which smooth muscle antibodies react in autoimmune hepatitis. F-Actin IGG antibodies are found in 52-85% of patients with Autoimmune Hepatitis (AIH) or chronic active hepatitis and in 22% of patients with Primary Biliary Cirrhosis (PBC). Anti-Actin antibodies have been reported in 3-18% of sera from normal healthy controls.