Acetylcholine Receptor Binding Antibody, Serum

What it is:
This blood test detects acetylcholine receptor (AChR) binding antibodies in the serum. These autoantibodies interfere with communication between nerves and muscles by blocking or destroying acetylcholine receptors.

Uses

• Diagnose myasthenia gravis (MG), an autoimmune neuromuscular disorder

• Differentiate MG from other neuromuscular conditions

• Monitor response to therapy in patients with MG

Symptoms That May Lead to the Test

• Muscle weakness that worsens with activity and improves with rest

• Drooping eyelids (ptosis)

• Double vision (diplopia)

• Difficulty swallowing or speaking

• Fatigue or generalized weakness

Abnormal Results

• Positive (high antibody levels):

  • Strongly suggests myasthenia gravis

  • May also be seen in patients with thymoma (thymus tumor)

• Negative (low/absent antibodies):

  • Does not completely rule out MG (some patients are seronegative)

Risks

• Minimal, limited to standard risks of a blood draw (mild pain, bruising, or dizziness).