Evaluating patients with chronic liver disease in whom the diagnosis of chronic active autoimmune hepatitis is suspected
Test Id | Reporting Name | Available Separately | Always Performed |
---|---|---|---|
SMAT | Smooth Muscle Ab Titer, S | No | No |
If smooth muscle antibody (SMA) screen is positive then the SMA titer will be performed at an additional charge.
Indirect Immunofluorescence
Actin
F-actin
Immunology Profile
SMA (Smooth Muscle Antibodies)
SMA, Anti
If smooth muscle antibody (SMA) screen is positive then the SMA titer will be performed at an additional charge.
Serum
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Specimen Volume: 0.8 mL
Collection Instructions: Centrifuge and aliquot serum into plastic vial
If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:
-General Request (T239)
0.4 mL
Gross hemolysis | Reject |
Gross lipemia | Reject |
Gross icterus | OK |
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Serum | Refrigerated (preferred) | 21 days | |
Frozen | 21 days |
Evaluating patients with chronic liver disease in whom the diagnosis of chronic active autoimmune hepatitis is suspected
If smooth muscle antibody (SMA) screen is positive then the SMA titer will be performed at an additional charge.
Autoimmune hepatitis (AIH) is caused by chronic inflammation within the liver, resulting in damage to the hepatocytes.(1) Initially, patients with AIH may be clinically asymptomatic, usually identified only through an incidental finding of abnormal liver function tests. At a more advanced stage, patients may manifest with symptoms such as jaundice, pruritus, or ascites, which are secondary to the more extensive liver damage. As implied by the name, AIH has many characteristics of an autoimmune disease, including female predominance, hypergammaglobulinemia, association with specific HLA alleles, responsiveness to immunosuppression, and the presence of autoantibodies. There are several autoantibodies associated with AIH, although the most common are smooth muscle antibodies (SMA). SMA are generally identified by indirect immunofluorescence using a smooth muscle substrate. The antigen specificity of SMA in the context of AIH has been identified as filamentous-actin (F-actin).(2) Because the clinical symptoms of AIH are nonspecific, being found in a variety of liver diseases (drug/alcohol-associated hepatitis, viral hepatitis, primary sclerosing cholangitis, etc), the diagnosis can be challenging. A set of diagnostic criteria for AIH has been published and includes the presence of various autoantibodies, elevated total IgG, evidence of hepatitis on liver histology, and absence of viral markers.(3) The combination of autoantibody serology, specifically SMA and anti-F-actin antibodies with liver histology and thorough clinical evaluation are useful in the evaluation of patients with suspected autoimmune hepatitis.
Negative
Reference values apply to all ages.
Seropositivity for smooth muscle antibodies (SMA) is consistent with a diagnosis of autoimmune hepatitis (AIH).
A negative result for SMA does not exclude a diagnosis of AIH.
Serologic tests for autoantibodies, including smooth muscle antibodies (SMA), should not be relied upon exclusively to determine the etiology or prognosis of patients with liver disease.
A positive result for SMA may occur in patients who do not have autoimmune hepatitis. A negative result does not exclude a diagnosis of autoimmune hepatitis.
1. Mieli-Vergani G, Vergani D, Czaja AJ, et al: Autoimmune hepatitis. Nat Rev Dis Primers. 2018 Apr 12;4:18017
2. Terziroli Beretta-Piccoli B, Mieli-Vergani G, Vergani D: Serology in autoimmune hepatitis: A clinical-practice approach. Eur J Intern Med. 2018 Feb;48:35-43
3. Hennes EM, Zeniya M, Czaja AJ, et al: Simplified criteria for the diagnosis of autoimmune hepatitis. Hepatology. 2008 Jul;48(1):169-176
The patient's serum in 1:20 and 1:40 (initial screening) dilutions is added to fresh tissue from mouse stomach/kidney and incubated; fluorescein-conjugated antiglobulin is then added. The slides are read with a fluorescence microscope.(Package insert: Kallestad Mouse Stomach/Kidney. Bio-Rad Laboratories, Inc; 01/2018)
Monday through Saturday
This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.
86015
Test Id | Test Order Name | Order LOINC Value |
---|---|---|
SMAS | Smooth Muscle Ab Screen, S | 26971-2 |
Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
---|---|---|
609515 | Smooth Muscle Ab Screen, S | 26971-2 |