Acetylcholine receptor antibody
Acetylcholine receptor antibody is a protein found in the blood of most people with myasthenia gravis. The antibody attacks receptors for a chemical called acetylcholine, which sends signals from nerves to muscles and between nerves in the brain.
How the test is performed
Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.
Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm.
Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.
In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.
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 test is used to help diagnose myasthenia gravis.
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.
What abnormal results mean
The presence of acetylcholinesterase antibody in the blood of someone who has symptoms of myasthenia gravis supports the diagnosis. Not having these antibodies, however, does not rule out myasthenia gravis. About 10 - 15% of people with myasthenia gravis do not have signs of this antibody in their blood.
What the risks are
There is very little risk involved with having your blood taken. Veins and arteries vary in size from one patient to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
- Excessive bleeding
- Fainting or feeling light-headed
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
ReferencesVincent A, Newson-Davis J. Disorders of neuromuscular transmission. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier. 2007: chap 448.
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; Daniel B. Hoch, PhD, MD, Assistant Professor of Neurology, Harvard Medical School, Department of Neurology, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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