Muscle-Specific Kinase (MuSK) Autoantibody, Serum
Test Mnemonic
MUSK
CPT Codes
- 86366 - QTY (1)
Aliases
- Muscle-specific receptor tyrosine kinase
- Seronegative MG (SNMG)
Performing Laboratory
Mayo Clinic Dpt of Lab Med & Pathology
Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 1.5 mL | Serum | No additive (Red) | Refrigerated |
Alternate Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 1.5 mL | Serum | SST (Gold) | Refrigerated |
Minimum Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 1 mL |
Stability
| Environmental Condition | Description |
|---|---|
| Refrigerated | 28 days |
| Frozen | 28 days |
| Ambient | 72 hours |
Days Performed
Tue, Thu
Turnaround Time
4 - 11 days
Methodology
| Name | Description |
|---|---|
| Radioimmunoassay (RIA) |
Reference Range
| MuSK Antibody Test | |||||
|---|---|---|---|---|---|
| Sex | Age From | Age To | Type | Range | Range Unit |
| < or = 0.02 nmol/L |
Special Info
This test is New York State approved.
Clinical Info
Testing is useful for: 1. Diagnosis of autoimmune muscle-specific kinase (MuSK) myasthenia gravis (MG) 2. Second-line test aiding diagnosis of autoimmune MG in patients with new onset acquired MG evident clinically and electrophysiologically, but negative first-line serological tests 3. Establishing a quantitative baseline value for MuSK antibodies that allows comparison with future levels if weakness is worsening. A positive result, in the appropriate clinical context, confirms the diagnosis of autoimmune muscle-specific kinase MG. Seropositivity justifies consideration of immunotherapy. Cautions: 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 MG are obscured by a superimposed steroid-induced myopathy.