The determination of antibodies against striated (skeletal) muscle fibers is used in the serological diagnosis of thymoma and myasthenia gravis, especially in patients younger than 45 years, as a screening test for severe myasthenia in elderly patients for whom antibodies against the acetylcholine receptor (AChR) are negative, in monitoring the efficacy of immunosuppressive therapy in patients with severe myasthenia and in the treatment of thymoma.
The autoantibodies against skeletal striated muscle fibers are immunoglobulins directed against the contractile elements of the skeletal muscle. These autoantibodies are found in 30% of adult patients with myasthenia gravis and in 80% of patients with thymoma. Their incidence increases as the age of onset of myasthenia increases and is rarely positive in ages younger than 20 years.
Possible Interpretations of Pathological Values
- Increase: Thymoma, autoimmune liver disorders, Lambert-Eaton syndrome, myasthenia gravis, myopathic disorders, small cell lung cancer, breast cancer. Patients receiving D-penicillamine and transplanted with bone marrow allograft may have positive titers.
Laboratory test results are the most important parameter for the diagnosis and monitoring of all pathological conditions. 70%-80% of diagnostic decisions are based on laboratory tests. The correct interpretation of laboratory results allows a doctor to distinguish "healthy" from "diseased".
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be interpreted in relation to each individual case and family history, clinical findings, and the results of other laboratory tests and information. Your personal physician should explain the importance of your test results.
At Diagnostiki Athinon we answer any questions you may have about the test you perform in our laboratory and we contact your doctor to get the best possible medical care.