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Test Code LAB3604 Muscle-Specific Kinase (MuSK) Autoantibody, Serum

Additional Codes

MUSK

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

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
Medical University of South Carolina Note:

On-campus collections: Tube to 99 or deliver to University Extension Hospital Room EH318.
 
Off-campus collections: Centrifuge and aliquot within 2 hours. Specimen to be stored/transported at Refrigerated temp. 

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus Reject

Reference Values

≤0.02 nmol/L

Interpretation

A positive result, in the appropriate clinical context, confirms the diagnosis of autoimmune muscle-specific kinase myasthenia gravis.

 

Seropositivity justifies consideration of immunotherapy.

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

Report Available

3 to 10 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

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)

Secondary ID

64277

Specimen Retention Time

28 days

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)