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Test Code MGA1 Myasthenia Gravis (MG) Evaluation, Adult

Useful For

Initial evaluation of patients aged 20 or older with symptoms and signs of acquired myasthenia gravis (MG)

 

Bone marrow transplant recipients with suspected graft-versus-host disease, particularly if weakness has appeared

 

Confirming that a recently acquired neurological disorder has an autoimmune basis (eg, MG)

 

Providing a quantitative baseline for future comparisons in monitoring a patient's clinical course and the response to immunomodulatory treatment

 

Raising likelihood of neoplasia

Profile Information

Test ID Reporting Name Available Separately Always Performed
MGEAI MG Adult Interpretation, S No Yes
ARBI ACh Receptor (Muscle) Binding Ab Yes Yes
ARMO ACh Receptor (Muscle) Modulating Ab No Yes
STR Striational (Striated Muscle) Ab, S Yes Yes

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
GD65S GAD65 Ab Assay, S Yes No
CRMWS CRMP-5-IgG Western Blot, S Yes 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.

 

See Myasthenia Gravis: Adult Diagnostic Algorithm in Special Instructions.

Method Name

ARBI, ARMO, GANG, GD65S, VGKC: Radioimmunoassay (RIA)

STR: Enzyme Immunoassay (EIA)

Reporting Name

MG Evaluation, Adult

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

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 to Friday; 6 a.m. and 4 p.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)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
MGA1 MG Evaluation, Adult 53706-8

 

Result ID Test Result Name Result LOINC Value
34272 MG Adult Interpretation, S 69048-7
8338 ACh Receptor (Muscle) Binding Ab 11034-6
8879 ACh Receptor (Muscle) Modulating Ab 30192-9
8746 Striational (Striated Muscle) Ab, S 8097-8

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

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)