F-Actin (Smooth Muscle) Antibody, IgG by ELISA with Reflex to Smooth Muscle Antibody, IgG Titer
Also known as: SMA R
Use
This test is useful in evaluating for autoimmune liver diseases, such as autoimmune hepatitis. It measures F-Actin (Smooth Muscle) Antibody, IgG levels using ELISA, and reflexes to Smooth Muscle Antibody, IgG Titer if the F-Actin levels are 20 Units or greater. Elevated levels of F-actin IgG antibodies are suggestive of autoimmune hepatitis or chronic active hepatitis. However, these antibodies can also be present in non-AIH conditions such as primary biliary cirrhosis and chronic hepatitis C infections.
Special Instructions
If F-Actin is 20 Units or greater, the test reflexes to Smooth Muscle Ab, IgG IFA titer with additional charges. The test should be performed when there is a suspicion of autoimmune hepatitis.
Limitations
F-actin IgG antibodies have increased sensitivity for autoimmune hepatitis but lower specificity than smooth muscle antibodies (SMA). Some patients may be SMA-positive but negative for F-actin IgG. In viral hepatitis, titers are generally less than 1:80 and transient, while in primary biliary cirrhosis, they are low, ranging from 1:20 to 1:40.
New York Approved
Methodology
Immunoassay (ELISA)
Biomarkers
LOINC Codes
- 44706-0
Result Turnaround Time
1-5 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1 mL
Minimum Volume
0.25 mL
Container
ARUP Standard Transport Tube
Collection Instructions
Collect serum in a Serum Separator Tube (SST).
Storage Instructions
Refrigerated.
Causes for Rejection
Plasma. Contaminated, heat-inactivated, hemolyzed, or lipemic specimens.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 48 hours |
| Refrigerated | 2 weeks |
| Frozen | 1 year |