Smooth Muscle Antibody Screen, Serum
Use
This test is used for the evaluation of patients with hepatitis of unknown origin, particularly associated with hypergammaglobulinemia and abnormal liver enzymes suggestive of autoimmune hepatitis (AIH). The presence of smooth muscle antibodies (SMA) may support the diagnosis of AIH following the exclusion of other causes of hepatitis. SMA are detected in up to 85% of AIH cases either alone or with other autoantibodies. They can also appear in the AIH/primary biliary cholangitis overlap syndrome.
Special Instructions
If ordering this test, it should be done alongside a comprehensive clinical evaluation and liver histology to diagnose autoimmune hepatitis. If the SMA screen is positive, the SMA titer will automatically be performed at an additional charge as per the reflex testing policy.
Limitations
Serologic tests like the SMA screen should not be solely relied upon to determine the etiology or prognosis of liver disease as they might yield positive results in patients without autoimmune hepatitis. Furthermore, a negative SMA test does not exclude the diagnosis of AIH due to variability in antibody presence and titers among patients.
New York Approved
Methodology
Immunoassay (Indirect Immunofluorescence)
Biomarkers
LOINC Codes
- 26971-2
- 26971-2
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
Serum gel (preferred) or red top tube
Collection Instructions
Centrifuge and aliquot serum into a plastic vial.
Causes for Rejection
Gross hemolysis, gross lipemia, heat-treated samples are to be rejected. Gross icterus is acceptable.
Stability Requirements
| Temperature | Period |
|---|---|
| Refrigerated | 21 days |
| Frozen | 21 days |