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Acetylcholine Receptor (AChR)-binding Antibodies With Reflex to AChR-modulating Antibody
- Acetylcholine Receptor (AChR) Profile With Reflex
Diagnose myasthenia gravis (MG); monitor response to treatment of myasthenia gravis
False positives can occur in patients with serum drawn within 48 hours of administration of general anesthesia and muscle relaxants. Antibodies to alpha-bungarotoxin may sometimes be found in patients treated with snake venom. Recently administered radioisotopes may interfere with the assay in unpredictable ways. Acetylcholine receptor autoantibodies are not typically found in congenital myasthenia gravis.
AChR-binding assay: radioimmunoassay (RIA); reflex assay AChR-modulating antibody: cell culture based radioimmunoassay (RIA)
Myasthenia gravis is an autoimmune disorder manifested by muscle weakness caused by the loss or dysfunction of acetylcholine receptors (AChR) of skeletal muscle. Autoantibodies (binding, blocking, and/or modulating) to postsynaptic AChRs are detectable in the serum of 90% of patients with generalized MG and in 55% to 70% of patients with ocular myasthenia. These autoantibodies interfere with normal neuromuscular function, causing muscle weakness and fatigue. Receptor antibody levels tend to rise several weeks before symptoms increase in patients with established MG. Remission after thymectomy is associated with a progressive decline in antibody levels. Consequently, measurements of AChR antibodies can be used in monitoring disease progression as well as the effects of treatment. Modulating antibodies are responsible for the degradation of AChR at the muscle cell surface. Modulating antibodies bind to two receptor molecules on the cell surface and accelerate internalization, triggering endocytosis and degradation. The relative increase in this degradation rate closely corresponds to the disease severity.
0.6 mL (Note: This volume does not allow for repeat testing.)
Red-top tube or gel-barrier tube
Separate serum from cells within 45 minutes of collection. Send serum in plastic transport tube.
Refrigerate; stable refrigerated for 14 days. Stable at room temperature for seven days or frozen for two months.
Causes for Rejection
Improper labeling; gross microbial contamination; specimen contaminated with anticoagulants; chylous serum; plasma specimen
An AChR-binding antibody result <0.25 will reflex to the AChR-modulating antibody at an additional charge.
|Order Code||Order Code Name||Order Loinc||Result Code||Result Code Name||UofM||Result LOINC|
|086003||Acetylchol Recep Bind Ab W/Rfx||085905||AChR Binding Abs, Serum||nmol/L||11034-6|
|Reflex Table for AChR Binding Abs, Serum|
|Order Code||Order Name||Result Code||Result Name||UofM||Result LOINC|
|Reflex 1||085935||AChR Modulating Ab||085935||AChR Modulating Ab||%||30192-9|