At a Glance

Why Become Tested?

To help diagnose myasthenia gravis (MG) and to distinguish between MG and other conditions with similar symptoms

When To Get Tested?

When you take symptoms that propose 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

Examination Preparation Needed?

None

Y'all may be able to observe your test results on your laboratory's website or patient portal. However, you are currently at Testing.com. You may have been directed here past your lab's website in club to provide you with groundwork information about the exam(s) you had performed. Y'all will need to return to your lab'due south 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 full general explanations of what results might mean for each test listed on the site, such as what a loftier or depression value might advise to your healthcare practitioner near your health or medical status.

The reference ranges for your tests tin can exist found on your laboratory study. They are typically plant to the correct of your results.

If you practise non have your lab study, 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 chosen "normal" values. Past 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 assistance identify possible conditions or diseases.

While accuracy of laboratory testing has significantly evolved over the past few decades, some lab-to-lab variability tin can occur due to differences in testing equipment, chemical reagents, and techniques. This is a reason why and so few reference ranges are provided on this site. Information technology is important to know that you lot must use the range supplied by the laboratory that performed your exam to evaluate whether your results are "inside normal limits."

For more data, please read the article Reference Ranges and What They Mean.

What is being tested?

Acetylcholine receptor (AChR) antibodies are autoantibodies produced by the allowed organisation that mistakenly target proteins called acetylcholine receptors that are located on muscles that yous tin can consciously or voluntarily control (known as skeletal musculus fibers). This test detects and measures AChR antibodies in the claret.

Muscle movement starts when an impulse is sent down a nervus to the nerve ending, where it stimulates the release of acetylcholine, a chemical substance (neurotransmitter) that transmits letters betwixt specific types of cells. Acetylcholine travels beyond the very minor gap between the nerve ending and a muscle cobweb (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 wrinkle.

AChR antibodies impede advice between nerves and skeletal muscles, inhibit muscle contraction, and cause rapid muscle fatigue by preventing activation of the acetylcholine receptors. They practice this in iii major ways:

  • Bounden antibodies attach to the receptors on nerve cells and may initiate an inflammatory reaction that destroys the receptors.
  • Blocking antibodies may sit down on the receptors, preventing acetylcholine from binding.
  • Modulating antibodies may cross-link the receptors, causing them to exist taken upwards into the muscle jail cell and removed from the neuromuscular junction.

The stop upshot 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 musculus command.

AChR antibodies may exist detected in different ways to decide which mechanism may be the trouble, and the antibodies may be referred to equally "binding," "blocking," or "modulating." Nonetheless, the technique that measures "binding" is the most unremarkably performed and, generally speaking, it is rare for the other two tests to be positive without the "binding" test being positive also. These other two tests may be useful when a healthcare practitioner strongly suspects myasthenia gravis and the "binding" examination is negative.

Common Questions

How is the test used?

An acetylcholine receptor (AChR) antibody test is used to help diagnose myasthenia gravis (MG) and to distinguish it from other conditions that may cause like symptoms, such every bit chronic muscle fatigue and weakness.

Three types of AChR antibodies may be tested:

  • AChR binding antibodies
  • AChR blocking antibodies
  • AChR modulating antibodies

The examination that measures binding antibodies is most commonly used because it is generally rare for the other 2 tests to be positive without the binding antibody test existence positive every bit well. These other 2 tests may be used when a healthcare practitioner strongly suspects myasthenia gravis and the binding antibiotic test is negative.

One or more of these AChR antibody tests may be ordered equally part of a panel of tests that may besides include a striated muscle antibody test to help establish a diagnosis. If AChR antibiotic test results are normal only a healthcare practitioner strongly suspects myasthenia gravis, an anti-MuSK (musculus-specific tyrosine kinase) antibody test may also exist ordered.

People with MG often accept an enlarged thymus gland and may have thymomas (typically beneficial tumors of the thymus). Located under the breastbone, the thymus is an active part of the immune organisation during childhood but usually becomes less agile during the teen years. If a thymoma is detected, such as during a chest computed tomography (CT) browse done for a unlike reason, and then an AChR antibiotic test may sometimes be used to determine whether the person has developed these antibodies.

When is it ordered?

The AChR antibody exam may be ordered when you have signs and symptoms that suggest myasthenia gravis, such as:

  • Drooping eyelid
  • Double vision
  • Decreased eye movement control
  • Difficulty swallowing, chewing, with choking, drooling and gagging
  • Slurred speech
  • Weak neck muscles
  • Trouble holding up your head
  • Difficulty breathing
  • Difficulty walking and an altered gait
  • Specific muscle weakness but normal feelings/sensations
  • Muscle weakness that worsens with sustained effort and improves with residue

In patients with known myasthenia gravis, echo AChR antibody tests may be washed to monitor response to therapy, to guide disease management, or to assess the take chances of AChR antibody transfer from a mother to her unborn child.

An AChR antibody test may sometimes exist ordered when a thymoma is detected during an imaging scan.

What does the test event hateful?

AChR antibodies are non ordinarily nowadays in the claret. They are autoantibodies and their presence indicates an autoimmune response.

If yous have AChR antibodies and symptoms of myasthenia gravis (MG), so it is likely that you accept this condition. The extent to which AChR antibodies are elevated does not predict the severity of the affliction at the time of diagnosis. Notwithstanding, changes in AChR antibody concentrations over time may assist inform the effectiveness of handling or predict the recurrence of illness. Therefore, repeat testing of AChR antibodies may be requested in some cases.

AChR antibodies may also exist positive with some thymomas, in people who are being treated with drugs such as penicillamine, with some small-scale prison cell lung cancers, with autoimmune liver disease, with Guillain-Barre syndrome, and with Lambert-Eaton myasthenic syndrome (a status associated with interference with the release of acetylcholine from the nerve ending).

A negative test event does not rule out MG. Upwardly to 50% of those with ocular MG (affecting only middle-related muscles) and about 10-xv% of those with generalized MG will be negative for AChR antibodies. Repeat testing of AChR antibodies in those with initially negative results may be useful as the concentration of antibodies may increase as the illness progresses, resulting in a subsequent positive AChR antibiotic test result.

Results from other tests for autoantibodies, such as anti-MuSK (musculus-specific kinase) antibody exam, anti-LRP4 (LDL-receptor-related protein 4) antibiotic test, and anti-striated muscle antibiotic test, may likewise aid in establishing a diagnosis.

Can this examination be performed in my healthcare provider'south office?

No, information technology is specialized testing that is not offered by every laboratory. Your blood sample will probable need to be sent to a reference laboratory for testing.

How serious is myasthenia gravis (MG)?

Most people who have it can alive a normal or near normal life with handling and monitoring. One of the most serious complications is a respiratory myasthenic crisis that tin can occur when muscles that control breathing are weakened. This can be a medical emergency and often requires hospitalization.

Can myasthenia gravis bear upon my centre?

No, the receptors for middle and smooth (digestive) muscles are dissimilar from skeletal muscles, and then they are non affected past the formation of AChR antibodies.

Is there anything I tin can exercise to prevent getting AChR binding antibodies?

No, the cause of MG is not known and the condition is not preventable.

Tin can MG exist passed from i person to another?

MG is not contagious, but a significant woman with MG can pass some of her AChR antibodies to her fetus. This can cause a newborn to take MG symptoms for several weeks later birth.

Can MG be inherited?

As an autoimmune process, no. Some people may inherit a genetic defect that causes congenital myasthenic syndrome, a condition with similar symptoms.

Is in that location anything else I should know?

Use of drugs such as succinylcholine tin can increment AChR antibodies.

People who have MG are more probable to also have other autoimmune disorders, such as rheumatoid arthritis or lupus.

Recent radioactive treatments can interfere with testing.

Related Content

View Sources

Sources Used in Current Review

2020 review performed past Michelle L. Parker, PhD, FCACB, Clinical Chemist, DynaLIFE Medical Labs.

Papadakis, Maxine A. & McPhee, Stephen J. (© 2016). Current Medical Diagnosis & Treatment 2016, 55th Edition: McGraw-Hill Education, USA. Pp 1028-1029.

Bakerman, Seymour. (© 2014). Bakerman's ABC's of Interpretive Laboratory Data, 5th Edition: Interpretive Laboratory Information, Inc, Scottsdale, AZ. Pp 3-iv and 65.

Gilhus, Northward.East., Tzartos, Southward., Evoli, A., Palace, J., Burns, T.M. & Verschuuren, J.J.M.M. (2019). Myasthenia gravis. Nat Rev Dis Primers. May 2;5(one):xxx. doi: x.1038/s41572-019-0079-y.

Maddison, P., Sadalage, Yard., Ambrose, P.A., Jacob, Due south. & Vincent, A. (2019). Fake-positive acetylcholine receptor antibody results in patients without myasthenia gravis. J Neuroimmunol. Jul fifteen;332:69-72. doi: 10.1016/j.jneuroim.2019.04.001.

Vincent, A. (2020). Antibodies and receptors: From neuromuscular junction to fundamental nervous system. Neuroscience. Mar 17 Epub ahead of print. doi: 10.1016/j.neuroscience.2020.03.009.

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Lazaridis, K. & Tzartos, S.J. (2020). Autoantibody specificities in myasthenia gravis: Implications for improved diagnostics and therapeutics. Forepart Immunol. Feb 14;11:212. doi: 10.3389/fimmu.2020.00212.

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(© 1995–2013). Acetylcholine Receptor (Muscle AChR) Binding Antibody, Serum. Mayo Clinic Mayo Medical Laboratories [On-line information]. Available online at http://world wide web.mayomedicallaboratories.com/examination-catalog/Overview/8338. Accessed Apr 2013.

Oasis, T. et. al. (2010) An Algorithm for Acetylcholine Receptor Antibiotic Testing in Patients with Suspected Myasthenia Gravis. Clinical Chemistry v 56 (half-dozen) 1028–1040 [On-line information]. Bachelor online at http://www.clinchem.org/content/56/six/1028.full. Accessed April 2013.

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