Acetylcholine receptor antibodies (ACRA)
Immunology
Sample and container requirements
Serum
Minimum volume required
1mL serum
Special requirements
None
Patient preparation
None
Sample viability
Turnaround time
21 days
Reference range
<0.4 nmol/L = negative. 0.4 - 0.5 nmol/L = borderline >0.5 nmol/L = positive
Clinical guidance
Acetylcholine receptor antibodies are a highly sensitive and specific marker for generalised myasthenia gravis. Please refer to LabTestsOnlineUK for more information: https://labtestsonline.org.uk/tests/acetylcholine-receptor-achr-antibody
Notes
About 10% patients with myasthenia may have no detectable ACR abs Up to 40% of Patients with exclusively ocular myasthenia may have negative ACR abs. In cases where ACR antibodies are negative and clinical presentation and suspicion of myesthenia remain high it is recommended that a repeat sample is sent and a request for ACR cluster antibodies by cell based assay is made.
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This information was last updated on 19 August 2026