Acetylcholine receptor antibody is a protein found in the blood of most people with myasthenia gravis. The antibody affects a chemical that sends signals from nerves to muscles and between nerves in the brain.
This article discusses the blood test for acetylcholine receptor antibody.
A blood sample is needed. Most of the time, blood is drawn from a vein located on the inside of the elbow or the back of the hand.
Most of the time you do not need to take special steps before this test.
How the Test will Feel
You may feel slight pain or a sting when the needle is inserted. You may also feel some throbbing at the site after the blood is drawn.
Why the Test is Performed
Normally, there is no acetylcholine receptor antibody (or less than 0.05 nmol/L) in the bloodstream.
Note: nmol = nanomole
Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
The example above shows the common measurement for results for these tests. Some laboratories use different measurements or may test different specimens.
What Abnormal Results Mean
An abnormal result means acetylcholine receptor antibody has been detected in your blood. It confirms the diagnosis of myasthenia gravis in people who have symptoms. Nearly one half of people with myasthenia gravis that is limited to their eye muscles (ocular myasthenia gravis) have this antibody in their blood.
However, the lack of this antibody does not rule out myasthenia gravis. About 1 in 5 people with myasthenia gravis do not have signs of this antibody in their blood. Your provider may also consider testing you for the muscle specific kinase (MuSK) antibody.
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Vincent A, Evoli A. Disorders of neuromuscular transmission. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 422.