Pathology Handbook

MuSK Antibodies

Clinical Indications

Acetylcholine receptor antibody negative myasthenia gravis

(Specialist request only)

Please note: Approximately 15% of patients with Myasthenia gravis are negative for acetylcholine receptor antibodies (AChR). Up to 50% of these AChR negative patients will have MuSK antibodies.

Test Includes

Detection of IgG antibodies to muscle-specific receptor tyrosine kinase.

Request Form 

Request via ICE.


Assay performed weekly.

Specific Criteria

It is essential to provide relevant clinical information.

Patient Preparation

No special preparation is required.

Turnaround Time

All samples are generally sent to referral laboratory within 3 working days of receipt in the laboratory. Samples are batched and the assay is performed weekly.


Red top tube. Gold top tube will be accepted.


7 ml


Vacutainer red top


Samples should be transported to the laboratory as soon as is practicably possible.

Lab Handling

Aliquot and store at 4-8°C prior to testing and at -20°C or below for up to 1 month after receipt.

Causes for Rejection

Unlabelled/inadequately labelled sample.

Inadequately completed request form.

Delay in sample reaching laboratory.

Reference Range

A qualitative result is given and samples are reported as Positive or Negative.