What are other Names for this Test? (Equivalent Terms)
- Acetylcholine Receptor Binding Antibody Blood Test
- AChR Antibody Blood Test
- AChR-Blocking Antibody Blood Test
What is Acetylcholine Receptor Antibody Blood Test? (Background Information)
- Acetylcholine (ACh) is a neurotransmitter - a chemical messenger that communicates signals involving neurons. One of its many functions includes stimulating the contraction of muscle fibers
- The interface of a muscle cell and neuron is called the neuromuscular junction. Between the two cells lies a space called the synapse, or synaptic cleft
- Neurons release ACh when they receive an electrical stimulus from other neurons. The ACh travels across the synapse and reaches the muscle cell. It then binds to receptors, called acetylcholine receptors (AChR) on the muscle cell
- Binding of ACh on the AChR of muscle starts a chain of events that end in muscle contraction. After a cycle of muscle contraction, the leftover ACh molecules must be degraded to avoid excessive muscle contraction. This is performed by the enzyme acetylcholine esterase (AChE)
- Problems with AChR, such as in the case of autoimmune disorders, interferes with the ability of ACh to stimulate muscle contraction. This leads to neuromuscular diseases such as myasthenia gravis (MG)
- Antibodies that target the body’s own AChR are implicated in MG. Antibodies are defense proteins that rid the body of foreign invaders. However, when antibodies mistakenly target native tissues, they cause autoimmune disease. These malfunctioning antibodies are called autoantibodies
- Antibodies to AChR are present in 85% of the cases of myasthenia gravis. These antibodies bind to the AChR, preventing ACh from fulfilling its function of stimulating muscle contraction
- The Acetylcholine Receptor Antibody Blood Test detects autoantibodies that target AChR. It is used to diagnose MG. There are 3 different tests:
- AChR-Binding Antibody Test
- AChR-Modulating Antibody Test
- AChR-Blocking Antibody Test
- Of these, the AChR-Binding Antibody Test is the most commonly ordered test.
What are the Clinical Indications for performing the Acetylcholine Receptor Antibody Blood Test?
Following are the clinical indications for performing the Acetylcholine Receptor Antibody Blood Test:
- Vision abnormalities
- Eye drooping
- Difficulty swallowing, speaking, and breathing
- Facial problems, including difficulty smiling and hanging jaw
- Muscle weakness
How is the Specimen Collected for the Acetylcholine Receptor Antibody Blood Test?
Following is the specimen collection process for Acetylcholine Receptor Antibody Blood Test:
Sample required: Blood
Process of obtaining blood sample in adults:
- A band is wrapped around the arm, 3-4 inches above the collection site (superficial vein that lies within the elbow pit)
- The site is cleaned with 70% alcohol in an outward spiral, away from the zone of needle insertion
- The needle cap is removed and is held in line with the vein, pulling the skin tight
- With a small and quick thrust, the vein is penetrated using the needle
- The required amount of blood sample is collected by pulling the plunger of the syringe out slowly
- The wrap band is removed, gauze is placed on the collection site, and the needle is removed
- The blood is immediately transferred into the blood container, which has the appropriate preservative/clot activator/anti-coagulant
- The syringe and the needle are disposed into the appropriate “sharp container” for safe and hygienic disposal
Preparation required: No special preparation is needed prior to the test.
What is the Significance of the Acetylcholine Receptor Antibody Blood Test Result?
- An Acetylcholine Receptor Antibody Blood Test value may indicate myasthenia gravis (MG)
The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario.
Additional and Relevant Useful Information:
- Certain factors may interfere with the results of the Acetylcholine Receptor Antibody Blood Test. These include amyotrophic lateral sclerosis (ALS) and autoimmune liver disease
Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider of the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.