Acetylcholine Receptor Blocking Antibody, Serum

Myasthenia Gravis (MG), AChR blocking antibody

Test Codes

EPIC: LAB8380, Beaker: XARBL, Quest: 34459

Department

Send Outs

Specimen Collection Criteria

Collect (preferred specimen): One Gold-top SST tube.
Also acceptable: One plain Red-top tube.

Physician Office/Draw Specimen Preparation

Let specimen clot 30-60 minutes then centrifuge to separate serum from cells. Transfer serum to plastic transport tube and maintain at room temperature (20-26°C or 68-78.8°F) prior to transport.

Preparation for Courier Transport

Transport: 1.0 mL serum, room temperature (20-26°C or 68-78.8°F). (Minimum: 0.5 mL)

Rejection Criteria

• Hemolyzed specimens.
• Severely lipemic specimens.
• Specimens not collected and processed as indicated.

In-Lab Processing

Let specimen clot 30-60 minutes then centrifuge to separate serum from cells within two hours of collection. Transfer serum to a plastic transport tube and refrigerate (2-8°C or 36-46°F).

Transport: 1.0 mL serum, room temperature (20-26°C or 68-78.8°F). (Minimum: 0.5 mL)

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 14 dayss
Refrigerated (2-8°C or 36-46°F): 14 days
Frozen (-20°C/-4°F or below): 30 days

Specimen Storage in Department Prior to Disposal:

Specimen retention time is determined by the policy of the reference laboratory. Contact the Send Outs Laboratory with any questions.

Laboratory

Sent to Quest Diagnostics, Wood Dale, IL.

Performed

Sunday, Tuesday, Thursday.
Results available in 4-5 days.

Reference Range

<15 % Inhibition

Test Methodology

Radioimmunoassay (RIA)

Clinical Utility

Acetylcholine Receptor Blocking Antibody – 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.

CPT Codes

86042

Contacts

Last Updated

11/19/2025