Test/Range/Collection

Acetylcholine receptor antibodies, serum

Negative

SST, red

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Physiologic Basis

Most patients with myasthenia gravis have detectable antibodies to the acetylcholine receptor (AChR). The AChR autoantibodies can be divided into binding, blocking and modulating antibodies, all of which are involved in the pathogenesis of myasthenia gravis. The binding antibody is most commonly tested. A sensitive radioimmunoassay (RIA) or enzyme-linked immunosorbent assay (ELISA) is available.

Interpretation

Positive in: Myasthenia gravis (sensitivity 87–98%, specificity 98–100%).

Comments

Antibody levels correlate with severity of autonomic failure. Antibodies can also be associated with other neurologic disorders unrelated to the autonomic nervous system.

Besides AChR antibodies, detection of autoantibodies targeting MuSK (muscle-specific kinase) and LRP4 (lipoprotein related protein 4) can also help diagnose myasthenia gravis, but with much lower sensitivity.

Berrih-Aknin S et al. Diagnostic and clinical classification of autoimmune myasthenia gravis. J Autoimmun 2014;48-49:143.  [PMID: 24530233]

Leite MI et al. Diagnostic use of autoantibodies in myasthenia gravis. Autoimmunity 2010;43:371.  [PMID: 20380582]

Zisimopoulou P et al. Serological diagnostics in myasthenia gravis based on novel assays and recently identified antigens. Autoimmun Rev 2013;12:924.  [PMID: 23537507]