ARUP's Laboratory Test Directory

Acetylcholine Receptor Blocking Antibody : 0099580

Mnemonic: ACHRBLO

Methodology: Semi-Quantitative Radioimmunoassay
Performed: Mon-Sat
Reported: 1-4 days
Specimen Required: Collect: 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: Refrigerated.

Unacceptable Conditions: Contaminated, hemolyzed, or severely lipemic specimens.

Stability (collection to initiation of testing): After separation from cells: Ambient: 2 hours; Refrigerated: 2 weeks; Frozen: 1 year (avoid repeated freeze/thaw cycles)

Reference Interval:
Negative: 0-15% blocking
Indeterminate: 16-24% blocking
Positive: 25% 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.

Refer to Statement B under Testing Information at http://www.aruplab.com.
CPT Code(s): 83516
Cross References: Myasthenia Gravis Antibodies (Acetylcholine Receptor Blocking Antibody)