Acetylcholine Receptor Blocking Antibody
Ordering Recommendation
Initial diagnostic testing for myasthenia gravis. For reflexive panel, which contains binding, blocking, and modulating antibodies, refer to Acetylcholine Receptor Antibody Reflexive Panel  (2001571).
Semi-Quantitative Flow Cytometry
1-4 days  
New York DOH Approval Status
This test is New York DOH approved.
Submit With Order
Specimen Required
Patient Preparation
Serum separator tube.  
Specimen Preparation
Separate serum from cells ASAP or within 2 hours of collection. Transfer 1 mL serum to an ARUP Standard Transport Tube. (Min: 0.5 mL)  
Storage/Transport Temperature
Unacceptable Conditions
Contaminated, hemolyzed, or severely lipemic specimens.  
After separation from cells: Ambient: 2 hours; Refrigerated: 2 weeks; Frozen: 1 year (avoid repeated freeze/thaw cycles)  
Reference Interval
Effective November 18, 2013
Negative: 0-​26% blocking
Indeterminate: 27-​41% blocking
Positive: 42% or greater blocking
Interpretive Data
Approximately 85-90% of patients with myasthenia gravis (MG) express antibodies to the acetylcholine receptor (AChR), which can be divided into binding, blocking, and modulating antibodies. Binding antibody can activate complement and lead to loss of AChR. Blocking antibody may impair binding of acetylcholine to the receptor, leading to poor muscle contraction. Modulating antibody causes receptor endocytosis resulting in loss of AChR expression, which correlates most closely with clinical severity of disease. Approximately 10-15% of individuals with confirmed myasthenia gravis have no measurable binding, blocking, or modulating antibodies.

Compliance Statement B: This test was developed and its performance characteristics determined by ARUP Laboratories. The U.S. Food and Drug Administration has not approved or cleared this test; however, FDA clearance or approval is not currently required for clinical use. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions.
CPT Code(s)
Component Test Code*Component Chart NameLOINC
0099580Acetylcholine Blocking Antibody42937-3
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
  • AChR Antibody
  • ACHR blocking antibody
  • Muscle nicotinic Acetylcholine Receptor (AChR) Blocking Antibody
  • Myasthenia Gravis Antibodies