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Muscle-Specific Kinase (MuSK), Antibody, IgG

MuSK Autoantibody, Muscle-Specific Receptor Tyrosine Kinase, Seronegative Myasthenia Gravis (MG)

Test Codes

EPIC: Miscellaneous Send Out (XMISC), ARUP: 3006198

NOTE:  The tests below must be ordered first. If the below tests are negative, testing will be sent out for MuSK.

• Acetylcholine Receptor Binding Antibody (LAB5921)
• Acetylcholine Receptor Blocking Antibody (LAB5922)
• Acetylcholine Receptor Modulating Antibody (LAB5923)

Department

Send Outs

Specimen Collection Criteria

Collect (preferred specimen): One plain Red-top tube.

Also acceptable: One Gold-top SST tube.

Physician Office/Draw Specimen Preparation

Let specimen clot 30-60 minutes then centrifuge to separate serum from cells within two hours of collection. Transfer serum to a plastic transport tube and refrigerate (2-8°C or 36-46°F).

Preparation for Courier Transport

Transport: 2.0 mL serum, refrigerated (2-8°C or 36-46°F). (Minimum: 0.5 mL)

Rejection Criteria

• Grossly lipemic specimen.
• Grossly icteric specimen.
• Hemolyzed specimens.
• Specimens not collected and processed as indicated.

In-Lab Processing

Let specimen clot 30-60 minutes then centrifuge to separate serum from cells within two hours of collection. Transfer serum to a plastic transport tube and refrigerate (2-8°C or 36-46°F).

Transport: 1.0 mL serum, refrigerated (2-8°C or 36-46°F). (Minimum: 0.5 mL)

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 48 hours
Refrigerated (2-8°C or 36-46°F): 14 days
Frozen (-20°C/-4°F or below): 1 month

Specimen Storage in Department Prior to Disposal:

Specimen retention time is determined by the policy of the reference laboratory. Contact the Send Outs Laboratory with any questions.

Laboratory

Sent to ARUP Laboratories, Salt Lake City, UT.

Performed

Monday, Wednesday and Friday.
Results available in 1-6 days.

Reference Range

See report.

Test Methodology

Semi-Quantitative Cell-Based Indirect Fluorescent Antibody

Interpretation

Muscle-specific kinase (MuSK) antibody is found in a subset of patients with myasthenia gravis, primarily those seronegative for muscle acetylcholine receptor (AChR) antibody. Decreasing antibody levels may be associated with therapeutic response; therefore, clinical correlation must be strongly considered. A negative test result does not rule out a diagnosis of myasthenia gravis. 

CPT Codes

83516

Contacts

Last Updated

9/19/2024