Acetylcholine receptor antibody

Definition

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.

Alternative Names

How the test is performed

A blood sample is needed. For information on how this is done, see: Venipuncture

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.

Normal Values

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 half of people with myasthenia gravis 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.

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)

Special considerations

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References

Vincent 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.

Sanders DB, Howard JF Jr. Disorders of neuromuscular transmission. In: Bradley WG, Daroff RB, Fenichel GM, Jankovic J, eds. Bradley: Neurology in Clinical Practice. 5th ed. Philadelphia, Pa: Butterworth-Heinemann Elsevier; 2008:chap 82.