Epic Code LAB1231962 Muscle-Specific Kinase (MuSK) Antibody Test

Test Name Alias

LAB1500 | Quest: 18842 | MUSK AB | MuSK Autoantibody, Muscle-Specific Receptor Tyrosine Kinase, Seronegative Myasthenia Gravis (MG), Muscle-Specific Kinase (MuSK), Antibody, IgG, Muscle-Specific Kinase (MuSK) Autoantibody, Serum

Interface Order Alias

1231962

Clinical Information

MuSK Antibody Test - Detection of antibodies to muscle-specific receptor tyrosine kinase (MuSK) (titer test).

Ordering Instructions

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)

Specimen Requirements

Specimen Collection Criteria

Collect (preferred specimen): . One Gold-top SST tube.

Also acceptable: One plain Red-top tube

Physician Office/Draw Specimen Preparation

Let specimen clot 30-60 minutes then centrifuge to separate serum from cells. Transfer serum to plastic transport tube and maintain at refrigerate (2-8°C or 36-46) prior to transport.

In-Lab Processing

Let specimen clot 30-60 minutes then centrifuge to separate serum from cells. Transfer serum to plastic transport tube and maintain at refrigerate (2-8°C or 36-46) prior to transport.

Specimen Transport Temperature

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

Rejection Criteria

Lipemic specimen.
Icteric specimen.
Hemolyzed specimens.
Specimens not collected and processed as indicated.

Specimen Stability

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 72 hours
Refrigerated (2-8°C or 36-46°F): 42 days
Frozen (-20°C/-4°F or below): 1 year

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.

Test Frequency

Performed: Sunday-Tuesday, Thursday.
Results available in 3-6 days.

Reference Range

Technical Result	<1:10 titer
Interpretation	Negative

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.

Performing Department

Send Outs

Performing Department Laboratory Location

Sent to Quest Diagnostics- Wood Dale, IL

Methodology

Radioimmunassay (RIA)

CPT

83516

LOINC

Unavailable

Reviewed Date

11/1/2025

Orderable Regions