Anti-Smooth Muscle Antibody Dx

Last updated: October 8, 2014

Synonyms: anti-Actin antibody, F Actin antibody

CPT Code:  86255

Description: Anti-smooth muscle antibody (AMSA) is an autoantibody to cytoskeletal components of smooth muscle – principally actin. Hence it is often referred to as anti-actin antibody. The etiology and function of these antibodies are unknown. These are commonly assessed when considering autoimmune hepatitis.

Method: ASMA is detected by indirect immunofluorescence using smooth muscle tissue as substrate.

Normal Values: A negative result has a titer <1:20.

Abnormal in:
 Autoimmune hepatitis: Typical of Type 1 AIH.  Titers are >1:160 in >95% of cases.
Primary biliary cirrhosis:  ASMA may be seen in as many as 30% of PBC patients.
Other conditions: Acute viral infections (e.g., mononucleosis), chronic viral hepatitis (especially hepatitis C), cirrhosis and other autoimmune diseases.

Indications: ASMA assay may be useful in diagnosing autoimmune chronic active hepatitis and distinguishing it from PBC.  The lack of specificity hinders its clinical usefulness.

Cost: $70–100.

Comment: Identification of specific cytoskeletal antigens and their antibodies may improve the usefulness of ASMA tests.

Soares A1, Cunha R, Rodrigues F, Ribeiro H. Smooth muscle autoantibodies with F-actin specificity. Autoimmun Rev 2009;8:713-6.  PMID: 19232552 
Zamanou A, Tsirogianni A, Terzoglou C, Balafas A, et al.  Anti-smooth muscle antibodies (ASMAs) and anti-cytoskeleton antibodies (ACTAs) in liver diseases: a comparison of classical indirect immunofluorescence with ELISA.  J Clin Lab Anal 2002; 16:194-201.   PMID:  12112392 

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