1-4 days after setup at PeaceHealth Laboratories’ reference lab; next run if repeat testing is necessary.
CPT Code:
83519-90
Specimen Collection Details
Collection:
One 7.5 mL serum separator tube (SST).
Handling:
Allow to clot, centrifuge and immediately separate serum from cells. Refrigerate. Avoid repeated freeze/thaw cycles.
Stability:
After separation from cells, specimen stable 2 hours ambient, 7 days refrigerated, or 12 weeks frozen.
Standard Volume:
1 mL serum.
Minimum Volume:
0.5 mL serum.
Transport:
Refrigerated.
Rejection Criteria:
Severely lipemic, contaminated, or hemolyzed specimen.
Reference Range:
Negative:
0-15% blocking
Indeterminate:
16-24% blocking
Positive:
≥ 25% 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.
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