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Acetylcholine receptor antibody |
| Definition: |
| Acetylcholine receptor antibody is an antibody found in the blood of people with myasthenia gravis. The acetylcholine receptor antibody attacks receptors for the neurotransmitter acetylcholine, which sends signals from nerves to muscles and from nerve to nerve in the brain. The antibody prevents transmission of the signal and causes muscle weakness. |
| How the test is performed: |
| A blood test can detect the presence of these antibodies. |
| How to prepare for the test: |
| No special preparation is required. |
| How the test will feel: |
| There may be a slight stinging or pricking sensation when blood is drawn, but this is usually mild and brief. |
| Why the test is performed: |
| This is a diagnostic test for myasthenia gravis. About 85% of people with generalized myasthenia and 60% of people with ocular myasthenia will have acetylcholine receptor antibodies in their blood. |
| Normal Values: |
| No acetylcholine receptor antibody (or less than .05 nmol) in the bloodstream is normal. Note: nmol = nanomole |
| What abnormal results mean: |
| Presence of acetylcholinesterase antibody in the blood of patients with symptoms of myasthenia gravis supports the diagnosis, but lack of these antibodies does not rule out this condition. About 10-15% of people with myasthenia gravis do not have evidence of antibody production using the commercially-available assays. |
| Special considerations: |
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Acetylcholine receptor antibody testing can confirm a diagnosis of myasthenia gravis for those suspected of having this disease. Symptoms include weakness that gets worse as they day progresses or with repeated exertion, blurred or double vision, nasal-sounding voice and difficulty swallowing. Other tests to diagnose myasthenia gravis include single-fiber EMG which shows a particular pattern in myasthenia gravis and an edrophonium challenge. The edrophonium challenge is done by injecting this drug intravenously and looking to see if there is improvement in strength by objective testing. Though no one test is specific and sensitive to make the diagnosis of myasthenia, if they are positive, it is likely that this is the correct diagnosis. While some people have a generally benign course, myasthenia gravis can be life threatening during "crises." This occurs when respiratory muscles become weak and breathing becomes difficult. Use of a respirator is then necessary to support breathing through the crisis and until medications and treatments can take effect. If symptoms of weakness, blurry or double vision, or change in voice occur, see your healthcare professional. |
Reviewed By: Galit Kleiner-Fisman MD, FRCP(C), Department of Neurology, University of Toronto, Toronto, Ontario, Canada. Review provided by VeriMed Healthcare Network.
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