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Order Code LAB1201 Acetylcholine Receptor (Muscle AChR) Binding Antibody, Serum

Reporting Name

ACh Receptor (Muscle) Binding Ab

Useful For

Supporting the diagnosis of autoimmune myasthenia gravis (MG) in adults and children

 

Distinguishing autoimmune from congenital MG in adults and children or other acquired forms of neuromuscular junction transmission disorders

 

An adjunct to the test for P/Q-type calcium channel binding antibodies as a diagnostic aid for Lambert-Eaton myasthenic syndrome

Testing Algorithm

This is the primary diagnostic test for myasthenia gravis.

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Serum


Ordering Guidance


Standalone testing (this test) is recommended in certain situations.

 

This test should not be requested in patients who have recently received radioisotopes, therapeutically or diagnostically, because of potential assay interference. The specific waiting period before specimen collection will depend on the isotope administered, the dose given, and the clearance rate in the individual patient. Specimens will be screened for radioactivity prior to analysis. Radioactive specimens received in the laboratory will be held for 1 week and assayed if sufficiently decayed or canceled if radioactivity remains.



Specimen Required


Patient Preparation: For optimal antibody detection, specimen collection is recommended prior to initiation of immunosuppressant medication.

Supplies: Sarstedt Aliquot Tube 5 mL (T914)

Collection Container/Tube:

Preferred: Red top

Acceptable: Serum gel

Submission Container/Tube: Plastic vial

Specimen Volume: 1.5 mL


Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 28 days
  Frozen  28 days
  Ambient  72 hours

Reference Values

≤0.02 nmol/L

Day(s) Performed

Monday through Sunday

CPT Code Information

86041

Method Description

Fetal and adult detergent-solubilized, acetylcholine receptors (extracted from cultures of rhabdomyosarcoma [RD] cells) labeled with (125)I-alpha-bungarotoxin are incubated with patient sample. Anti-human IgG is then added to form an immunoprecipitate. After washing the precipitated immune complexes, the amount of (125)I-labeled receptor in the immunoprecipitate is measured using a gamma-counter. The amount of gamma emission in the precipitate is proportional to the amount of AChR-IgG in the sample. Results are reported in units of precipitated antigen (nMol) per L of patient sample.(Griesmann GE, Kryzer TJ, Lennon VA. Autoantibody profiles of myasthenia gravis and Lambert-Eaton myasthenic syndrome. In: Rose NR, Hamilton RG, eds. Manual of Clinical and Laboratory Immunology. 6th ed. ASM Press; 2002:1005-1012; Waters P, Pettingill P, Lang B. Detection methods for neural autoantibodies. Handb Clin Neurol. 2016;133:147-163. doi:10.1016/B978-0-444-63432-0.00009-8)

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus Reject

Method Name

Radioimmunoassay (RIA)

Forms

If not ordering electronically, complete, print, and send a Neurology Specialty Testing Client Test Request (T732) with the specimen.