What this test measures
Three subtypes: (1) AChR binding antibodies (most common, detected in ~80% of generalised MG, ~50% of ocular MG) — diagnostic; (2) AChR blocking antibodies — measure functional block; (3) AChR modulating antibodies — measure receptor internalisation. Binding alone is usually sufficient for diagnosis. Seronegative MG (10-15% of cases) requires anti-MuSK or anti-LRP4 antibodies for diagnosis.
Why it matters
Myasthenia gravis presents with fluctuating weakness — typically ocular (ptosis, diplopia), bulbar (dysphagia, dysarthria), proximal limb, and respiratory. Indian neurological practice routinely includes AChR antibody as first-line MG workup. Positive result enables confident diagnosis and guides therapy (pyridostigmine, immunosuppressants, IVIG, thymectomy). Thymoma is associated with ~10-15% of AChR-positive MG and warrants CT chest at diagnosis.
How to prepare
No fasting required. Random sample. Disclose any recent IVIG / plasmapheresis (transient antibody decrease), thymectomy history, current immunosuppression (steroids, azathioprine, mycophenolate), and current symptoms.
Markers & reference ranges
Reference ranges below are typical adult values. Your lab's reported range may differ slightly based on the assay platform and patient demographics — always read your report against the range printed on it.
| Marker | Normal range | If low | If high |
|---|---|---|---|
| AChR Binding Antibody (nmol/L)[1][2] | Negative: < 0.5 nmol/L | Negative: AChR-positive MG ruled out. Consider seronegative MG — test for anti-MuSK and anti-LRP4 antibodies if clinical suspicion remains. | Positive: > 0.5 nmol/L confirms AChR-positive MG in the right clinical context. Titre does NOT correlate well with disease severity but persistent very high values can suggest poorer prognosis. Order CT chest to rule out thymoma. |
MG antibody workup
| Antibody | Sensitivity | When to order |
|---|---|---|
| AChR binding | 80% generalised, 50% ocular | First-line for all suspected MG |
| Anti-MuSK | 40% AChR-negative MG | AChR negative + clinical MG |
| Anti-LRP4 | 20% double-seronegative MG | AChR + MuSK negative |
| AChR modulating / blocking | Rarely additive | Complex / atypical cases |
Frequently asked questions
How accurate is the test?
AChR binding antibody is 80-90% sensitive for generalised MG and 50% for ocular MG, with >99% specificity. Negative result doesn't rule MG out — pursue anti-MuSK and anti-LRP4 testing.
Why is CT chest ordered?
Thymoma occurs in 10–15% of AChR-positive MG patients. Diagnosis at the time of MG diagnosis is important — thymectomy is therapeutic for MG and curative for thymoma.
Does titre correlate with severity?
Weakly. Titre doesn't reliably track activity — individual symptoms and Quantitative Myasthenia Gravis (QMG) score are better activity markers. Persistent very high titres may suggest worse prognosis.
Will treatment lower the antibody level?
Yes, modestly — IVIG, plasmapheresis, and B-cell depleting therapy (rituximab) reduce antibody levels. Titre often falls with chronic immunosuppression but doesn't need to be normalised to control disease.
Is this hereditary?
No — AChR-MG is autoimmune, not inherited. Family clustering is rare. Congenital myasthenic syndromes (genetic, AChR-Ab-negative) are distinct conditions.
How long does the test take?
Typically 5–7 working days at most labs (specialised radioimmunoassay or ELISA).
Related Autoimmune / Rheumatology tests
Tests commonly ordered alongside ACETYLCHOLINE RECEPTOR AUTOANTIBODY, or that help interpret an unexpected result.
Sources & references
- AAN — Myasthenia Gravis Practice Parameter · accessed 2026-05-30T00:00:00.000Z
- NIH MedlinePlus — AChR Antibody · accessed 2026-05-30T00:00:00.000Z
- Mayo Clinic Labs — AChR Antibodies · accessed 2026-05-30T00:00:00.000Z
- MGFA · accessed 2026-05-30T00:00:00.000Z
Book with Zelnoo
Get your ACETYLCHOLINE RECEPTOR AUTOANTIBODY test done at home — transparent prices, NABL-accredited labs.
Zelnoo lets you compare diagnostic test prices across NABL-accredited labs in Mumbai & Thane, book a free home phlebotomist visit, and receive digital reports in 24–48 hours into a consent-first report vault. No subscriptions, no membership fees — pay only for the test you book.
Book ACETYLCHOLINE RECEPTOR AUTOANTIBODY now