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Test Code MGRM Myasthenia Gravis (MG) Evaluation with MuSK Reflex, Serum

Useful For

Diagnosis for autoimmune myasthenia gravis in adults and children

 

Distinguishing autoimmune from congenital myasthenia gravis in adults and children

 

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
MGRMI MG Interpretive Comments No Yes
ARBI ACh Receptor (Muscle) Binding Ab Yes Yes
STR Striational (Striated Muscle) Ab, S Yes Yes
ARMO ACh Receptor (Muscle) Modulating Ab No Yes

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
MUSK MuSK Autoantibody, S Yes No
GD65S GAD65 Ab Assay, S Yes No
CRMWS CRMP-5-IgG Western Blot, S No No
GANG AChR Ganglionic Neuronal Ab, S No No
VGKC Neuronal (V-G) K+ Channel Ab, S No No

Testing Algorithm

If acetylcholine receptor (AChR) modulating antibodies are ≥90% and striational antibodies are ≥1:120, then AChR ganglionic neuronal autoantibody, glutamic acid decarboxylase autoantibody, neuronal voltage-gated potassium channel autoantibody, and CRMP-5-IgG Western blot will be performed at an additional charge.

 

If AChR binding antibodies are ≤ to 0.02 and AChR modulating antibodies are ≤ 20%, then muscle-specific kinase (MuSK) autoantibody will be performed at an additional charge.

 

See Myasthenia Gravis Evaluation with MuSK Reflex Algorithm in Special Instructions.

Reporting Name

MG Evaluation with MuSK Reflex, S

Specimen Type

Serum


Specimen Required


Container/Tube:

Preferred: Red top

Acceptable: Serum gel

Specimen Volume: 3 mL

Additional Information: Patient should have no general anesthetic or muscle-relaxant drugs in the previous 24 hours.


Specimen Minimum Volume

2 mL

Specimen Stability Information

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

Reject Due To

Hemolysis

Mild OK; Gross reject

Lipemia

Mild OK; Gross reject

Icterus

Mild OK; Gross reject

Other

NA

 

Reference Values

ACh RECEPTOR (MUSCLE) BINDING ANTIBODY

≤0.02 nmol/L

 

ACh RECEPTOR (MUSCLE) MODULATING ANTIBODIES

0-20% (reported as __% loss of AChR)

 

STRIATIONAL (STRIATED MUSCLE) ANTIBODIES

<1:120

Day(s) and Time(s) Performed

ACh receptor (muscle) binding antibody: Monday through Friday;11 a.m., 6 p.m., and 10 p.m.; Saturday; 6 a.m.; Sunday; 6 a.m. and 10 a.m.

ACh receptor (muscle) modulating antibodies: Monday through Thursday; 2 p.m.; Saturday; 8 a.m.

Striational (striated muscle) antibodies: Monday through Friday; 4 a.m. and 3 p.m.; Saturday; 6 a.m.

CRMP-5-IgG Western blot: Monday, Wednesday, Friday; 8 a.m.

AChR ganglionic neuronal antibody: Monday through Friday; 11 a.m. and 6 p.m.; Saturday; 6 a.m.; Sunday; 6 a.m.

Neuronal VGKC autoantibody: Monday through Friday; 11 a.m. and 6 p.m.; Saturday; 6 a.m.; Sunday; 6 a.m.

GAD65 antibody assay: Monday through Friday; 6 a.m. and 4 p.m.

MUSK autoantibody assay: Tuesday and Thursday; 6 a.m.

Performing Laboratory

Mayo Medical Laboratories in Rochester

CPT Code Information

83519-ACh receptor (muscle) binding antibody

83519-ACh receptor (muscle) modulating antibodies

83520-Striational (striated muscle) antibodies

83519-AChR ganglionic neuronal antibody (if appropriate)

83519-Neuronal VGKC autoantibody (if appropriate)

84182-CRMP-5-IgG Western blot (if appropriate)

86341-GAD65 antibody assay (if appropriate)

83519-MuSK Autoantibody (if appropriate)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
MGRM MG Evaluation with MuSK Reflex, S Unable to Verify

 

Result ID Test Result Name Result LOINC Value
8338 ACh Receptor (Muscle) Binding Ab 11034-6
8879 ACh Receptor (Muscle) Modulating Ab 30192-9
8746 Striational (Striated Muscle) Ab, S 8097-8
37213 MG Interpretive Comments 69048-7

Method Name

ARBI, ARMO, GANG, VGKC: Radioimmunoassay (RIA)

STR: Enzyme Immunoassay (EIA)

CRMWS: Western Blot

Secondary ID

64289

Forms

If not ordering electronically, complete, print, and send a Neurology Specialty Testing Client Test Request (T732) with the specimen (http://www.mayomedicallaboratories.com/it-mmfiles/neurology-request-form.pdf)