Muscle Specific Kinase (MUSK) Autoantibody, Serum

Message

For Specimen Integrity during Extreme Weather see the “Lockbox Usage in Extreme Weather” document at the top of this page.

Test Code

MUSK

CPT Codes
86366

Preferred Specimen

1.5 mL Serum from Red Top tube

Minimum Volume

1 mL

Other Acceptable Specimens

Serum from SST

Transport Container

Pour off tube

Transport Temperature

Refrigerated

Specimen Stability

Room Temperature: 72 hours
Refrigerated: 28 days
Frozen: 28 days

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Gross hemolysis, gross lipemia, gross icterus

Methodology
Radioimmunoassay (RIA)

Setup Schedule

Monday - Friday

Report Available

3 - 10 days

Limitations

Immunosuppressant therapy is a common cause of false-seronegativity. It is, therefore, important to perform a comprehensive serological evaluation before initiating immunosuppressant therapy. Interpretation of a patient’s serological and clinical status is further complicated when characteristic signs of myasthenia gravis are obscured by a superimposed steroid-induced myopathy.

Clinical Significance

Diagnosis of autoimmune muscle-specific kinase (MuSK) myasthenia gravis Second-order test to aid in the diagnosis of autoimmune myasthenia gravis when first-line serologic tests are negative Establishing a quantitative baseline value for MuSK antibodies that allows comparison with future levels if weakness is worsening.

Performing Laboratory
Mayo Clinic Laboratories
200 First Street SW
Rochester, MN 55905

Last Updated: January 1, 2024

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.