Muscle-Specific Kinase (MuSK) Antibody, IgG by CBA-IFA with Reflex to Titer, Serum
Also known as: MuSK SER
Use
This test is used as a secondary diagnostic tool for generalized or ocular myasthenia gravis in patients who do not have detectable acetylcholine receptor (AChR) antibodies. It identifies the presence of Muscle-specific kinase (MuSK) antibody, which is found in a subset of patients with myasthenia gravis, primarily those seronegative for AChR antibody. Monitoring decreasing antibody levels can indicate a therapeutic response, necessitating clinical correlation. However, a negative test result does not rule out myasthenia gravis.
Special Instructions
If the MuSK SER antibody IgG result is positive, a titer will be automatically added. Additional charges will apply for the titer test. This test involves a semi-quantitative cell-based indirect fluorescent antibody method. Ensure separation from cells as soon as possible, ideally within 2 hours of collection, and transfer the serum into an ARUP standard transport tube.
Limitations
This test does not guarantee a definitive diagnosis of myasthenia gravis due to potential seronegative results. It cannot entirely rule out the disease, especially in cases where antibody levels fluctuate. The assay is developed by ARUP Laboratories and has not received clearance or approval from the U.S. Food and Drug Administration, though it is performed in a CLIA-certified lab for clinical use. Test results should always be considered in conjunction with other clinical variables.
New York Approved
Methodology
Cell-based / Cytometry
Biomarkers
LOINC Codes
- 38362-0
Result Turnaround Time
1-6 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
2 mL
Minimum Volume
0.5 mL
Container
ARUP standard transport tube
Collection Instructions
Collect one 4 mL plain red or serum separator tube (SST).
Storage Instructions
Store refrigerated.
Causes for Rejection
Grossly lipemic, icteric, or hemolyzed specimens.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 48 hours |
| Refrigerated | 2 weeks |
| Frozen | 1 month |