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Test Code LAB3324 Muscle-Specific Kinase (MuSK) Autoantibody, Serum

Additional Codes

MUSK Ab

Useful For

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

Reporting Name

MuSK Autoantibody, S
Seattle Children's Hospital Note:

SCH Clinical System Name: MUSK Antibody

Specimen Type

Serum


Specimen Required


Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

Collection Container/Tube:

Preferred: Red top

Acceptable: Serum gel

Submission Container/Tube: Plastic vial

Specimen Volume: 1.5 mL

Collection Instructions: Centrifuge and aliquot serum into a plastic vial.


Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 28 days
  Frozen  28 days
  Ambient  72 hours

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus Reject

Reference Values

≤0.02 nmol/L

Method Description

(125)I-labeled recombinant human muscle-specific kinase (MuSK) is incubated with patient sample. Anti-human IgG is then added to form an immunoprecipitate. After washing the immunoprecipitate, the amount of (125) I-labeled antigen in the immunoprecipitate is measured using a gamma-counter. The amount of gamma emission in the precipitate is proportional to the amount of MuSK-IgG in the sample. Results are reported as units of precipitated antigen (nMol) per L of patient sample.(Lavrnic D, Losen M, Vujic A, et al. The features of myasthenia gravis with autoantibodies to MuSK. J Neurol Neurosurg Psychiatry. 2005;76[8]:1099-1102)

Day(s) Performed

Monday through Friday

Seattle Children's Hospital Note:

TAT: 5 - 12 d

Report Available

3 to 10 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test was developed using an analyte specific reagent. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

86366

LOINC Code Information

Test ID Test Order Name Order LOINC Value
MUSK MuSK Autoantibody, S 51716-9

 

Result ID Test Result Name Result LOINC Value
64277 MuSK Autoantibody, S 51716-9

Method Name

Radioimmunoassay (RIA)

Forms

If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:

-Neurology Specialty Testing Client Test Request (T732)

-General Request (T239)