Actin (Smooth Muscle) Antibody (IgG)

Test Code

Alias/See Also

CPT Codes

Preferred Specimen
0.5 mL serum

Minimum Volume
0.25 mL

Transport Container
Transport tube

Transport Temperature
Room temperature

Specimen Stability
Room temperature: 14 days
Refrigerated: 14 days
Frozen: 30 days

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Gross hemolysis • Lipemia • Microbially contaminated serum • Specimens containing heavy, visible particulate

Enzyme Linked Immunosorbent Immunoassay (ELISA)

Setup Schedule

Report Available
1-3 days

Reference Range
<20 U Negative

≥20 U


Antibodies recognizing actin are the main component of smooth muscle antibodies associated with autoimmune liver disease. Actin antibodies are found in approximately 75% of patients with autoimmune hepatitis (AIH) type 1, approximately 65% of patients with autoimmune cholangitis, approximately 30% of patients with primary biliary cirrhosis, and approximately 2% of healthy people. High values are closely correlated with AIH type 1.

Clinical Significance
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.

Performing Laboratory
Quest Diagnostics Nichols Institute-San Juan Capistrano, CA
33608 Ortega Highway
San Juan Capistrano, CA 92675-2042

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.