Neurology Myasthenia Gravis Reflexive Panel
Label Mnemonic: MGEA
Epic Lab Code: LAB7630
Downtime Form: A-1a Miscellaneous Request
Commercial Mail-out Laboratory
5231 RCP
356-8593
Specimen(s):
Serum
Specimen Instructions:
Patient should have no general anesthetic or muscle-relaxant drugs in the previous 24 hours.

Testing Algorithm:
If acetylcholine receptor (AChR) modulating antibodies are > or =90% and striational antibodies are > or =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.
Collection Medium:
Red top tube 5 mL (Clot Activator)
Minimum:
Preferred Minimum: 3 mL serum
Absolute Minimum: 2 mL serum
Testing Schedule:
Monday through Sunday
Turn Around Time:
3 days upon receipt at reference laboratory
Reference Range:
ACh Receptor (Muscle) Binding Ab: < or =0.02 nmol/L
ACh Receptor (Muscle) Modulating Ab: 0-20% loss of AChR
Striational (Striated Muscle) Antibodies: <1:120
GAD65 Ab Assay, S: < or =0.02 nmol/L
CRMP-5-IgG Western Blot, S: Negative
AChR Ganglionic Neuronal Ab, S: < or =0.02 nmol/L
Neuronal (V-G) K+ Channel Ab, S: < or =0.02 nmol/L
Interpretive Data:
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.
Comments:
This mailout test requires Neurology attending approval. Mailouts staff will not process order without approval. If approval is given, the name of the Neurology attending can be selected in the drop-down menu to the right of the approval warning in Epic when ordering the test.

Depending on results of initial testing, the reference laboratory performing this mailout test can initiate further reflex testing that will involve additional charges for the patient.

If muscle AChR modulating antibody value is (or exceeds) 90% acetylcholine receptor (AChR) loss and striational antibody is detected, thymoma is likely. Reflexive testing will include CRMP-5-lgG Western blot, ganglionic AChR antibody, and VGKC antibody (which are frequent with thymoma).
Methodology:
Radioimmunoprecipitation (RIA); Enzyme Immunoassay (EIA); Western Blot
CPT Code:
83519-ACh receptor (muscle) binding antibody
83519-ACh receptor (muscle) modulating antibodies
83520-Striational (striated muscle) antibodies
86341-GAD65 antibody assay (if appropriate)
84182-CRMP-5-IgG Western blot (if appropriate)
83519-AChR ganglionic neuronal antibody (if appropriate)
83519-Neuronal VGKC autoantibody (if appropriate)