Acetylcholine is an important chemical that facilitates muscle contractions by acting as a messenger between nerves and muscles. In individuals with myasthenia gravis (MG), an abnormal protein known as acetylcholine receptor (AChR) antibody is often produced. The AChR antibody blood test is used to determine the level of acetylcholine receptor (AChR) antibody present in the bloodstream.
AChR antibody disrupts the normal activity of acetylcholine, leading to initial muscle weakness in the eye. Symptoms such as double vision or drooping eyelids may occur. Myasthenia gravis is characterized as an autoimmune disease because the body generates antibodies that target the usual function of acetylcholine. MG is a rare condition that can affect individuals across all age groups. It predominantly affects women under the age of 40 and men over the age of 60. This condition is not contagious. However, there are cases where newborn babies of mothers with MG may exhibit symptoms for a period of a few weeks to several months. These symptoms can be effectively managed and treated.
When is theAChR antibody blood test ordered?
The AChR antibody blood test is typically requested when there are signs and symptoms of myasthenia gravis, such as
- Drooping eyelid
- Double vision
- Reduced control over eye movements
- Challenges in swallowing and chewing, accompanied by choking, drooling, and gagging
- Slurred speech
- Weak neck muscles
- Trouble holding up your head
- Shortness of breath
- Difficulty walking and an altered gait
- Weakness in the legs, arms neck, and fingers
Individuals with a confirmed diagnosis of myasthenia gravis may require periodic AChR antibody testing to monitor treatment response, assist in disease management, and evaluate the possibility of AChR antibody transmission from a pregnant woman to her baby. An AChR antibody test may also be recommended in cases where a thymoma (rare cancer on your thymus) is discovered through imaging.
The normal range for AChr antibody blood test
Normally, AChR antibodies are not found (or they are <0.05 nmol/L) in the blood. These autoantibodies are indicative of an autoimmune response. The reference ranges for these values may vary slightly from one laboratory to another. It is recommended to discuss the interpretation of your specific test results with your healthcare provider.
If you exhibit symptoms of myasthenia gravis (MG) and test positive for AChR antibodies, it is highly probable that you have this condition. However, it is important to understand that the extent of AChR antibody elevation does not serve as an indicator of disease severity at the time of diagnosis. However, monitoring changes in AChR antibody concentrations over time can offer valuable information regarding treatment effectiveness and the likelihood of disease recurrence. Therefore, in certain instances, healthcare providers may request repeat testing of AChR antibodies.
In addition to certain thymomas, AChR antibodies may also show positive results in individuals diagnosed with small cell lung cancers, autoimmune liver disease, Guillain-Barre syndrome (a rare autoimmune disorder that affects the nerves), and Lambert-Eaton myasthenic syndrome (a condition that is associated with the interference of acetylcholine release from the nerve ending).
It is important to note that a negative test result does not definitively rule out the presence of MG. Up to 50% of individuals with ocular MG, which affects muscles related to the eyes, and approximately 10-15% of those with generalized MG may not test positive for AChR antibodies. It is advisable to conduct additional tests for AChR antibodies in individuals with initially negative results, as the antibody levels could rise as the disease advances, leading to a positive AChR antibody test result in the future.
The Achr antibody test plays a vital role in diagnosing the autoimmune disease myasthenia gravis. By detecting antibodies that target the acetylcholine receptor, this test enables early detection and timely treatment, ultimately improving patient outcomes and quality of life.
