Acetylcholine Receptor Binding Antibody (AChR) Test

The acetylcholine receptor (AChR) binding antibody test is used to help diagnose Myasthenia Gravis (MG) and to distinguish it from other conditions that may cause similar symptoms, such as chronic muscle fatigue and weakness. AChR binding autoantibodies are diagnostic of MG, and are found in 85-90% of MG patients.

AChR antibodies hinder the action of acetylcholine, a chemical (neurotransmitter) that transmits messages between nerve cells. The antibodies do this in three major ways-- by binding, blocking or modulating antibodies.

This AChR test measures "binding" antibodies, and is most commonly used to test for MG because it is generally rare for the other two tests to be positive without the "binding" test being positive as well.

AChR antibodies are not normally present in the blood; they are autoantibodies and their presence indicates an autoimmune response.

If binding antibodies are negative, assays for modulating and blocking antibodies should be considered.