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Test ID STR Striational (Striated Muscle) Antibodies, Serum

Useful For

As a serological aid in the diagnosis of thymoma, especially in patients with onset of myasthenia gravis (MG) younger than 45 years

 

As a screening test for MG in older patients, especially when tests for muscle AChR antibodies are negative

 

Serial measurements are useful in monitoring the efficacy of immunosuppressant treatment in patients with MG

 

Serial measurements are useful after treatment of thymoma

 

Serial measurements in recipients of D-penicillamine or bone marrow allografts may be useful in monitoring autoimmune complications and graft-versus-host disease, respectively

Testing Algorithm

See Paraneoplastic Evaluation Algorithm in Special Instructions

Method Name

Enzyme Immunoassay (EIA)

Reporting Name

Striational (Striated Muscle) Ab, S

Specimen Type

Serum

Container/Tube:

Preferred: Red top

Acceptable: Serum gel

Specimen Volume: 0.5 mL

Specimen Minimum Volume

0.3 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Refrigerated (preferred) 28 days
  Frozen  28 days
  Ambient  72 hours

Clinical Information

Autoantibodies directed against the contractile elements of striated muscle are found in 30% of adult patients with myasthenia gravis and in 80% of those with thymoma. These antibodies may also be detected in patients with: Lambert-Eaton myasthenic syndrome, small-cell lung carcinoma, breast carcinoma, patients treated with D-penicillamine, bone marrow transplant recipients having graft-versus-host disease, and autoimmune liver disorders.

 

While this test is used as a serological aid in the diagnosis of thymoma, especially in patients with onset of myasthenia gravis (MG) younger than 45 years, it is more predictive of thymoma when accompanied by a muscle acetylcholine receptor (AChR) modulating antibody value of ≥90% AChR loss and is most predictive of thymoma when accompanied by CRMP-5-IgG. Serial measurements are useful after treatment of thymoma. Measurements of muscle AChR binding, muscle AChR modulating antibody, and CRMP-5-IgG (if initially positive) are also recommended.

Reference Values

<1:120

Cautions

A negative result does not exclude the presence of thymoma (20% are negative).

Day(s) Performed

Monday through Friday; 3 p.m.

Report Available

3 days

Performing Laboratory

Mayo Medical Laboratories in Rochester

Test Classification

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 U.S. Food and Drug Administration.

CPT Code Information

83520

NY State Approved

Yes