Acetylcholine Receptor (AChR) Antibody
- Also Known As:
- AChR Antibody
- Muscle nicotinic Acetylcholine Receptor (AChR) Binding Antibody
- Myasthenia Gravis Antibodies
- Acetylcholine Receptor Binding Antibody
- Acetylcholine Receptor Blocking Antibody
- Acetylcholine Receptor Modulating Antibody
- Formal Name:
- Myasthenia Gravis (MG) Evaluation
- serum

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.At a Glance
Why Get Tested?
To help diagnose myasthenia gravis (MG) and to distinguish between MG and other conditions with similar symptoms
When To Get Tested?
When you have symptoms that suggest MG, such as a drooping eyelid, double vision, difficulty chewing or swallowing, and/or weakness in specific voluntary muscles
Sample Required?
A blood sample drawn from a vein in your arm
Test Preparation Needed?
None
You may be able to find your test results on your laboratory’s website or patient portal. However, you are currently at Testing.com. You may have been directed here by your lab’s website in order to provide you with background information about the test(s) you had performed. You will need to return to your lab’s website or portal, or contact your healthcare practitioner in order to obtain your test results.
Testing.com is an award-winning patient education website offering information on laboratory tests. The content on the site, which has been reviewed by laboratory scientists and other medical professionals, provides general explanations of what results might mean for each test listed on the site, such as what a high or low value might suggest to your healthcare practitioner about your health or medical condition.
The reference ranges for your tests can be found on your laboratory report. They are typically found to the right of your results.
If you do not have your lab report, consult your healthcare provider or the laboratory that performed the test(s) to obtain the reference range.
Laboratory test results are not meaningful by themselves. Their meaning comes from comparison to reference ranges. Reference ranges are the values expected for a healthy person. They are sometimes called “normal” values. By comparing your test results with reference values, you and your healthcare provider can see if any of your test results fall outside the range of expected values. Values that are outside expected ranges can provide clues to help identify possible conditions or diseases.
While accuracy of laboratory testing has significantly evolved over the past few decades, some lab-to-lab variability can occur due to differences in testing equipment, chemical reagents, and techniques. This is a reason why so few reference ranges are provided on this site. It is important to know that you must use the range supplied by the laboratory that performed your test to evaluate whether your results are “within normal limits.”
For more information, please read the article Reference Ranges and What They Mean.
What is being tested?
Acetylcholine receptor (AChR) antibodies are autoantibodies produced by the immune system that mistakenly target proteins called acetylcholine receptors that are located on muscles that you can consciously or voluntarily control (known as skeletal muscle fibers). This test detects and measures AChR antibodies in the blood.
Muscle movement starts when an impulse is sent down a nerve to the nerve ending, where it stimulates the release of acetylcholine, a chemical substance (neurotransmitter) that transmits messages between specific types of cells. Acetylcholine travels across the very small gap between the nerve ending and a muscle fiber (this gap is called the “neuromuscular junction”). When acetylcholine reaches the muscle fiber, it binds to one of many acetylcholine receptors or “docking stations” and activates it, initiating muscle contraction.
AChR antibodies impede communication between nerves and skeletal muscles, inhibit muscle contraction, and cause rapid muscle fatigue by preventing activation of the acetylcholine receptors. They do this in three major ways:
- Binding antibodies attach to the receptors on nerve cells and may initiate an inflammatory reaction that destroys the receptors.
- Blocking antibodies may sit on the receptors, preventing acetylcholine from binding.
- Modulating antibodies may cross-link the receptors, causing them to be taken up into the muscle cell and removed from the neuromuscular junction.
The end result of this interference is the development of myasthenia gravis (MG), a chronic autoimmune disorder associated with the presence of these antibodies and with their effects on muscle control.
AChR antibodies may be detected in different ways to determine which mechanism may be the problem, and the antibodies may be referred to as “binding,” “blocking,” or “modulating.” However, the technique that measures “binding” is the most commonly performed and, generally speaking, it is rare for the other two tests to be positive without the “binding” test being positive as well. These other two tests may be useful when a healthcare practitioner strongly suspects myasthenia gravis and the “binding” test is negative.
Common Questions
View Sources
Sources Used in Current Review
2020 review performed by Michelle L. Parker, PhD, FCACB, Clinical Chemist, DynaLIFE Medical Labs.
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