Ordering Recommendation

Establish or confirm a clinical diagnosis of myasthenia gravis. Includes acetylocholine receptor (AChR) binding and blocking antibodies with reflex to AChR modulating antibodies or MuSK antibodies.

Mnemonic
MG R PAN
Methodology

Quantitative Radioimmunoassay/Semi-Quantitative Flow Cytometry

Performed

Sun-Sat

Reported

3-8 days

New York DOH Approval Status
This test is New York DOH approved.
Specimen Required
Patient Preparation
Collect

Serum Separator Tube (SST).

Specimen Preparation

Separate 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

Refrigerated.

Unacceptable Conditions

Contaminated, hemolyzed, or severely lipemic specimens.

Remarks
Stability

After separation from cells: Ambient: 48 hours; Refrigerated: 2 weeks; Frozen: 1 month  (avoid repeated freeze/thaw cycles)

Reference Interval
Test Number
Components
Reference Interval
0080009 Acetylcholine Receptor Binding Antibody
Negative 0.0-0.4 nmol/L
Positive 0.5 nmol/L or greater

0099580 Acetylcholine Receptor Blocking Antibody Effective November 18, 2013
Negative: 0-26% blocking
Indeterminate: 27-41% blocking
Positive: 42% or greater blocking

0099521 Acetylcholine Receptor Modulating Antibody Effective August 20, 2012
Negative 0-45% modulating
Positive 46% or greater modulating

3001576 Muscle-Specific Kinase (MuSK) Antibody, IgG
Negative 0.00-0.03 nmol/L
Positive 0.04 nmol/L or greater

Interpretive Data

Approximately 85-90 percent 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 percent of individuals with confirmed myasthenia gravis have no measurable binding, blocking, or modulating antibodies.

Compliance Category

Laboratory Developed Test (LDT)

Note

If Acetylcholine Receptor Binding Antibody result is greater than 0.4 nmol/L or Acetylcholine Receptor Blocking Antibody result is greater than 26 percent, then Acetylcholine Receptor Modulating Antibody (ARUP test code 0099521) will be added. If Acetylcholine Receptor Binding Antibody result is less than or equal to 0.4 nmol/L, then Muscle-Specific Kinase (MuSK) Ab, IgG (ARUP test code 3001576) will be added. Additional charges apply.

Hotline History
N/A
CPT Codes

83519; 83516; if reflexed, add 83516, 83519

Components
Component Test Code* Component Chart Name LOINC
0080009 Acetylcholine Binding Antibody 11034-6
0099580 Acetylcholine Blocking Antibody 42937-3
* 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.
Aliases
  • AChR Antibody
  • AChR reflex panel
  • Muscle nicotinic Acetylcholine Receptor (AChR) Binding Antibody
  • Muscle-Specific Kinase Antibody by RIA
  • Muscle-Specific Receptor Tyrosine Kinase
  • MuSK
  • MuSK Autoantibody
  • Myasthenia Gravis Antibodies
  • Myasthenia Gravis Antibodies Reflex
Myasthenia Gravis Reflexive Panel