Specimen

Serum

Collection Medium:

Minimum:

Recommended minimum: 0.5 mL serum
Adult and Pediatric absolute minimum: 0.3 mL serum

Analytic Time:

1 week

Reference Range:

Negative:      0  - 20% modulation
Indeterminate: 21 - 25% modulation
Positive:      26% or greater modulation

Test
Limitations:

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 antibody.  Binding antibody can 
activate complement and lead to loss of AChR.  Blocking antibody may 
impair AChR binding 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 
antibody.

Methodology:

Radioreceptor Assay

CPT Code:

83519