Smooth Muscle Antibody Titer, Serum
Use
Autoimmune hepatitis (AIH) is a chronic disease resulting from immune-mediated liver injury with varied clinical manifestations. The disease often involves a combination of genetic predisposition and environmental triggers that precipitate an autoimmune response against the liver. Smooth muscle antibodies (SMA) are generally identified by indirect immunofluorescence and are key markers in diagnosing AIH, especially type 1, which is linked to the presence of these antibodies. SMA, along with anti-F-actin antibodies, help in evaluating patients suspected of having AIH, potentially contributing to the International Autoimmune Hepatitis Group diagnostic score. These antibodies can also be detected in cases of primary biliary cholangitis/AIH overlap syndrome.
Special Instructions
This test is not orderable directly and is performed as part of a reflex test. When smooth muscle antibody (SMA) screen results are equivocal or positive, the SMA titer will be performed at an additional charge.
Limitations
Serologic tests for autoantibodies should not be solely relied upon to determine the cause or prognosis of liver diseases. A positive result for SMA does not definitively indicate autoimmune hepatitis, and a negative result does not rule it out. Testing for smooth muscle autoantibodies is part of a broader diagnostic approach that includes clinical evaluation and liver histology.
New York Approved
Methodology
Immunoassay (Indirect Immunofluorescence)
Biomarkers
LOINC Codes
- 5358-7
- 5358-7
Result Turnaround Time
2-4 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
0.8 mL
Minimum Volume
0.4 mL
Container
Plastic vial
Collection Instructions
Centrifuge and aliquot serum into a plastic vial.
Causes for Rejection
Gross hemolysis, Gross lipemia, Heat-treated specimens
Stability Requirements
| Temperature | Period |
|---|---|
| Refrigerated | 21 days |
| Frozen | 21 days |