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Test Code ACRAB Acetylcholine Receptor (Muscle AChR) Binding Antibody, Serum

Additional Codes

Mayo Test ID


Sunrise Clinical Manager (SCM) Orderable:

Acetylcholine Receptor Binding Antibody 

AllScripts (AEHR) Orderable: 

Acetylcholine Receptor Binding Antibody


Reporting Name

ACh Receptor (Muscle) Binding Ab

Useful For

A first-order test for the laboratory diagnosis of myasthenia gravis (MG)


Detecting "subclinical MG" in recipients of D-penicillamine, in patients with thymoma without clinical evidence of MG, and in patients with graft-versus-host disease


Distinguishing acquired disease (90% positive) from congenital disease (negative)


Monitoring disease progression in MG or response to immunotherapy


An adjunct to the test for P/Q-type calcium channel binding antibodies as a diagnostic aid for Lambert-Eaton myasthenic syndrome (LES) or primary lung carcinoma

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type


Specimen Required

Patient Preparation: 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 1 week and assayed if sufficiently decayed, or canceled if radioactivity remains.


Preferred: Red top

Acceptable: Serum gel

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) and Time(s) Performed

Monday through Friday; 11 a.m., 6 p.m., 10 p.m.

Saturday; 6 a.m.

Sunday; 6 a.m., 10 a.m.

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
ARBI ACh Receptor (Muscle) Binding Ab 11034-6


Result ID Test Result Name Result LOINC Value
8338 ACh Receptor (Muscle) Binding Ab 11034-6

Clinical Information

Myasthenia gravis (MG) is characterized by weakness and easy fatigability that are relieved by rest and anticholinesterase drugs. The weakness in most cases results from an autoantibody-mediated loss of functional acetylcholine receptors (AChR) in the postsynaptic membrane of skeletal muscle.


Demonstration of muscle AChR autoantibodies in a patient's serum supports the diagnosis of acquired (autoimmune) MG, and quantitation provides a baseline for future comparisons.


Muscle AChR antibodies are not found in congenital forms of MG and are uncommon in neurologic conditions other than acquired MG, with the exception of patients with paraneoplastic autoimmune neurological disorders, and Lambert-Eaton myasthenic syndrome (LES) with or without cancer (13% of LES patients have positive results for muscle AChR binding or striational antibodies). Patients with autoimmune liver disease are also frequently seropositive.


The assay for muscle AChR binding antibodies is considered a first-order test for the laboratory diagnosis of MG, and for detecting "subclinical MG" in recipients of D-penicillamine, in patients with thymoma without clinical evidence of MG, and in patients with graft-versus-host disease.

Analytic Time

3 days

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus Reject

NY State Approved


Method Name

Radioimmunoassay (RIA)


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

Northwell Health Laboratories Additional Information:

Computer Interface Code

   PDM #   5900210