9358. Acetylcholine receptors, IgG antibodies

Antibodies to acetylcholine receptors are a specific marker of myasthenia. This disease manifests itself with the following symptoms: drooping eyelid, diplopia (double vision), speech, breathing, and gait impairment, tachycardia, and muscle weakness.

This is the primary serological test for diagnosing myasthenia, but the presence of antibodies can also indicate other pathologies (thymoma, small cell lung cancer, autoimmune liver diseases). Therefore, a blood chemistry test, titin antibody testing, electrolytes, and CPK are also prescribed, as well as instrumental imaging (CT, MRI, PET).

Myasthenia gravis (MG) is an autoimmune disease that disrupts neuromuscular transmission and leads to muscle weakness. The primary mechanism for the development of MG is the formation of antibodies to acetylcholine receptors (AChRs), which block or destroy the receptors necessary for transmitting nerve impulses to muscles.

Clinical manifestations include ptosis (drooping eyelids), severe muscle weakness after exercise, difficulty swallowing, and gait changes. Symptoms can be localized (ocular MG) or generalized, affecting different muscle groups.

Anti-AChR antibody testing is a sensitive and specific method for diagnosing MG. Their detection rate varies depending on the disease form: in ocular MG, they are positive in 63% of cases, while in generalized MG, they are positive in 87%. Even in remission, AChR antibodies persist in 58% of patients.

Myasthenia gravis (MG) is often associated with thymus gland pathology. Thymic hyperplasia is detected in 60-70% of patients with acetylcholine receptor (AChR) antibodies, and thymoma (an epithelial tumor of the thymus) is found in 10-15%. Although myasthenia gravis is primarily associated with the thymus, in rare cases (<1%) it may be accompanied by other malignancies (lung or stomach), which is likely related to general dysregulation of the immune system. Chest CT is used to diagnose thymoma, which is the standard method for identifying the tumor, its location, and its structure. Determination of AChR antibodies has a higher sensitivity than electromyography and is used for serological monitoring in the event of a change in the clinical condition or during immunosuppressive therapy. If the test is negative, but MG is suspected, additional tests are performed, including determination of blocking and modulating antibodies to acetylcholine. A positive test for AChR antibodies may indicate subclinical myasthenia gravis, as well as reactivity to curare-like drugs and antibiotics. These parameters are important not only for diagnosing myasthenia gravis but also for detecting thymoma, as 59% of patients with thymoma and myasthenia gravis have positive results.

• For the diagnosis of myasthenia gravis (MG).
• For the presence of atypical symptoms (atypical muscle weakness, swelling of the face and difficulty breathing) for rheumatoid arthritis, MS.
• To monitor the progression of MG symptoms and response to treatment.

• Venous blood

In order to exclude factors that may affect the test results, we recommend to follow the preparation rules: