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Test Code MGRMM Myasthenia Gravis Evaluation with Muscle-Specific Kinase (MuSK) Reflex, Serum

Additional Codes

 

MAYO Test ID

MGMR

EPIC Test ID

LAB3312


Ordering Guidance


This test should not be requested for patients who have recently received radioisotopes, therapeutically or diagnostically, because of potential assay interference. The specific waiting period before specimen collection will depend on the isotope administered, the dose given, and the clearance rate in the individual patient. Specimens will be screened for radioactivity prior to analysis. Radioactive specimens received in the laboratory will be held 1 week and assayed if sufficiently decayed or canceled if radioactivity remains.



Specimen Required


Patient Preparation: For optimal antibody detection, specimen collection is recommended prior to initiation of immunosuppressant medication or intravenous immunoglobulin treatment. 

Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

Collection Container/Tube:

Preferred: Red top

Acceptable: Serum gel

Submission Container/Tube: Plastic vial

Specimen Volume: 3 mL

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


Forms

If not ordering electronically, complete, print, and send a Neurology Specialty Testing Client Test Request (T732) with the specimen.

Useful For

Diagnosing autoimmune myasthenia gravis (MG) in adults and children

 

Distinguishing autoimmune from congenital MG in adults and children or other acquired forms of neuromuscular junction transmission disorders

 

Establishing a quantitative baseline value that allows comparison with future levels if weakness is worsening

Profile Information

Test ID Reporting Name Available Separately Always Performed
MGMRI MG with MuSK Interpretation, S No Yes
ARBI ACh Receptor (Muscle) Binding Ab Yes Yes

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
ACMFS AChR Modulating Flow Cytometry, S No No
MUSK MuSK Autoantibody, S Yes No

Testing Algorithm

If acetylcholine receptor (AChR)-binding antibodies are greater than 0.02 nmol/L, then AChR muscle modulating antibody will be performed at an additional charge.

 

If AChR-binding antibodies are 0.02 nmol/L or less, then muscle-specific kinase (MuSK) autoantibody will be performed at an additional charge.

 

If unable to report AChR binding antibody due to interfering substances, then AChR muscle modulating antibody will be performed at an additional charge.

 

If unable to report AChR binding antibody due to interfering substances and AChR muscle modulating antibody is negative, then MuSK autoantibody will be performed at an additional charge.

Method Name

ARBI, MUSK: Radioimmunoassay (RIA)

ACMFS: Flow Cytometry

MGMRI: Medical Interpretation

Reporting Name

MG Evaluation MuSK Reflex, S

Specimen Type

Serum

Specimen Minimum Volume

2 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

Test ID

Reporting Name

Methodology

Reference Value

MGMRI

MG with MuSK Interpretation, S

Interpretation

NA

ARBI

ACh Receptor (Muscle) Binding Ab

Radioimmunoassay (RIA)

≤0.02 nmol/L

Reflex Information:

Test ID

Reporting Name

Methodology

Reference Value

ACMFS

AChR Modulating Flow Cytometry, S

Flow Cytometry

Negative

MUSK

MuSK Autoantibody, S

RIA

≤0.02 nmol/L

Day(s) Performed

Profile tests: Monday through Sunday; Reflex tests: Varies

Report Available

3 to 10 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

86041

86043 (if appropriate)

86366 (if appropriate)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
MGMR MG Evaluation MuSK Reflex, S 53706-8

 

Result ID Test Result Name Result LOINC Value
608981 MG with MuSK Interpretation, S 69048-7
8338 ACh Receptor (Muscle) Binding Ab 97558-1