Myasthenia Gravis (MG) is a chronic autoimmune disease. It affects skeletal muscle strength by creating blockages in the communication between nerves and muscles. The first symptoms of this disease are often the development of double vision or a drooping eyelid. It can also affect the muscles of the face and neck, creating problems with speaking and swallowing. Weakness of the muscles tends to vary over time and can improve with rest.
The Myasthenia Gravis blood test is ordered to detect acetylcholine receptor antibodies that are produced when this disease is present. The antibodies are known to hinder the neurotransmitters that are responsible for communication. Three specific tests may be ordered to determine what action the antibodies are taking to cause MG signs and symptoms.
When To Ask About the Myasthenia Gravis Blood Test
If there are any signs and symptoms of muscle weakness around the eyes, face, or neck that is accompanied by changes to vision, speech, or swallowing, then a medical appointment should be scheduled right away.
Sometimes people who have MG will have an enlarged thymus gland as their primary symptom. There may also be the development of benign tumors on the gland. A CT scan of the thymus gland can determine if it is enlarged and exclude other reasons for its enlargement.
Some people also have muscle weakness in other areas of the body. Have specific muscle weakness, but normal feelings or sensations, can be an indication of MG. Weakness worsens with effort, but improves with rest. There may also be problems walking, changes to a person’s gait, difficulty in holding up the head, and trouble breathing.
It is important to note that many of the symptoms of MG are similar symptoms to MS or ALS. Only a doctor can determine what diagnosis is occurring. Do not rely solely on information from the internet as this can create additional stress which can worsen any symptoms that are being experienced.
What Do My Test Results Mean?
The most common Myasthenia Gravis blood test is often referred to as the “binding” test. This is because the antibodies the test detects are attaching themselves to the acetylcholine receptors of the nerve cells. This, in turn, creates an inflammatory reaction which eventually destroys the nerve cells and causes the symptoms of MG.
If the binding test is negative, there are two other tests which may be ordered if a medical provider strongly suspects MG. It is just rare for these two tests to be positive if the binding test is negative. The first test, called the “blocking” test, will look for antibodies that are sitting on the receptors to prevent the binding action from taking place.
The second test, referred to as the “modulating” test, looks for antibodies which may cross-link the receptors. This causes the antibodies to be taken up to the muscle cells and removed from the cell junctions.
A baseline antibody test may also be ordered to determine MG activity or to determine how effective a therapy for the disease happens to be.
Negative tests do not necessarily rule out Myasthenia Gravis. Up to half of people with MG that is related only to the eye muscles will have negative blood test results. About 1 in 10 people with a generalized form of MG will also have negative test results.
Here’s What You Need to Know
Certain drugs are known to increase the antibodies that are detected by the Myasthenia Gravis blood test. The most common of these is succinylcholine. Certain radioactive treatments or diagnosis efforts can also interfere with the testing process and provide incomplete results.
When MG is confirmed as a diagnosis, there is also a good chance that there may be another autoimmune disorder present. Issues such as systemic lupus or rheumatoid arthritis are just two possibilities. Because of this, a medical provider may order several tests to exclude other potential health issues which may need to be treated.
If all of the MG blood tests come back as negative, a medical provider may opt for a blood test to detect anti-muscle-specific kinase antibodies. About 70% of those who test negative for MG antibodies, but have generalized MG symptoms, will test positive on this blood test.
The Myasthenia Gravis blood test results explained here are intended as a guideline only. Use this information to discuss your signs and symptoms with your medical provider to see if this blood test is right for you. Only your doctor, with information from your medical history and tests like these, can diagnose MG.