Acetylcholine Receptor Blocking Antibody

Test Code
34459

Preferred Specimen
1 mL serum

Minimum Volume
0.5 mL

Transport Container
Plastic screw-cap vial

Transport Temperature
Room temperature

Specimen Stability
Room temperature: 14 days
Refrigerated: 14 days
Frozen: 30 days

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Microbially contaminated • Gross hemolysis • Grossly lipemic

Methodology
Radioimmunoassay (RIA)

Limitations
Antibodies may not be found in congenital myasthenia.

Reference Range
< 15% of Inhibition

Clinical Significance
Myasthenia Gravis (MG) is an autoimmune neuromuscular disorder characterized by muscle weakness, most commonly due to autoantibody-mediated loss of functional acetylcholine receptors (AChR) in the neuromuscular junction. AChR binding autoantibodies are diagnostic of MG, and are found in 85-90% of MG patients. AChR blocking autoantibodies prevent inter-action of binding antibodies with the AChR. Fewer than 1% of patients have blocking antibodies without binding antibodies. Blocking antibodies are present in about 50% of patients with MG, but rare in other conditions. Therefore, blocking antibodies have utility in ruling out a possible false positive binding assay and detecting the rare patient without AChR binding antibodies.

Performing Laboratory
Quest Diagnostics Nichols Institute
14225 Newbrook Drive
Chantilly, VA 20153




The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.