F-Actin and Mitochondrial M2 Antibodies, IgG by ELISA with Reflex to Smooth Muscle Antibody (SMA), IgG by IFA
Ordering Recommendation

May be helpful when evaluating for autoimmune liver disease. For a more comprehensive reflex panel, refer to Autoimmune Liver Disease Evaluation with Reflex to Smooth Muscle Antibody (SMA), IgG by IFA (2007210).

Semi-Quantitative Enzyme-Linked Immunosorbent Assay/Semi-Quantitative Indirect Fluorescent Antibody
1-4 days
New York DOH Approval Status
This test is New York DOH approved.
Submit With Order
ARUP Consult®
Disease Topics
Specimen Required
Patient Preparation
Serum separator tube (SST). 
Specimen Preparation
Separate serum from cells ASAP or within 2 hours of collection. Transfer 0.5 mL serum to an ARUP Standard Transport Tube. (Min: 0.3 mL) 
Storage/Transport Temperature
Unacceptable Conditions
Non-serum, heat-inactivated, contaminated, grossly icteric, severely lipemic, grossly hemolyzed specimens or inclusion of fibrin clot.. 
After separation from cells: Ambient: 48 hours; Refrigerated: 2 weeks; Frozen: 1 year (avoid repeated freeze/thaw cycles) 
Reference Interval
Test NumberComponentsReference Interval
0050065Mitochondrial M2 Antibody, IgG (ELISA)20.0 Units or less: Negative
20.1-24.9 Units: Equivocal
25.0 Units or greater: Positive
0055248F-Actin (Smooth Muscle) Antibody, IgG19 Units or less 20-30 Units 31 Units or greaterNegative  Weak Positive - Suggest repeat testing in two to three weeks with fresh specimen. Positive - Suggestive of autoimmune hepatitis type 1 or chronic active hepatitis.
Smooth Muscle Antibody, IgG Titer<1:20 = Normal - No antibody detected.
1:20-1:80 = Weak Positive - Suggest repeat testing in two to three weeks with fresh specimen.
1:160 or greater = Positive - Suggestive of autoimmune hepatitis or chronic active hepatitis.

Interpretive Data
F-Actin Antibody, IgG by ELISA:F-actin antibodies have demonstrated a greater sensitivity and specificity for autoimmune liver disease than anti-smooth muscle antibodies.

If F-Actin, IgG by ELISA is 20 Units or greater, then Smooth Muscle Antibody (SMA), IgG by IFA titer will be added. Additional charges apply.
CPT Code(s)
83516 x2; if reflexed, add 86256
Component Test Code*Component Chart NameLOINC
0050065Mitochondrial (M2) Antibody, IgG14251-3
0055248F-Actin (Smooth Muscle) Ab, IgG by ELISA44706-0
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
  • AMA M2
  • AMA M2 reflex
  • anti-M2
  • Autoimmune Liver Disease Differentiation Panel
  • F Actin
  • F-actin
  • F-Actin (Smooth Muscle) Antibody, IgG
  • M2
  • Mito M2
  • Mitochondrial Antibodies, Serum
  • Mitochondrial M2 Antibody, IgG (ELISA)
  • Mitochondrial MS reflex
  • SMA
  • SMA Titer
  • Smooth Muscle Antibodies, Serum
  • Smooth Muscle Antibody, IgG Titer