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Test Code MISCLM Myasthenia Gravis (MG)/Lambert-Eaton Syndrome (LES) Evaluation

Additional Codes

 

MAYO Test ID

MGL1

EPIC Test ID

LAB2608

 

Useful For

Confirming the autoimmune basis of a defect in neuromuscular transmission (eg, myasthenia gravis: MG, Lambert-Eaton syndrome: LES)

 

Distinguishing LES from 2 recognized autoimmune forms of MG

 

Raising the index of suspicion for cancer, particularly primary lung carcinoma (N-type calcium channel antibody)

 

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

Profile Information

Test ID Reporting Name Available Separately Always Performed
MGLEI MG Lambert-Eaton Interpretation, S No Yes
CCPQ P/Q-Type Calcium Channel Ab No Yes
CCN N-Type Calcium Channel Ab 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
CRMWS CRMP-5-IgG Western Blot, S Yes No
GANG AChR Ganglionic Neuronal Ab, S No No

Testing Algorithm

If acetylcholine receptor (AChR) modulating antibodies are ≥90% and striational antibodies are ≥1:120, then AChR ganglionic neuronal antibody and CRMP-5-IgG Western blot will be performed at an additional charge.

 

This evaluation is recommended for patients presenting with an acquired defect of neuromuscular transmission in whom the differential diagnosis includes Lambert-Eaton syndrome (LES). It is not recommended for patients with a past history of, or risk factors for, lung cancer and/or concurrent neurological symptoms/signs not attributable to LES; for those situations, order PAVAL / Paraneoplastic Autoantibody Evaluation, Serum. Testing for a newly recognized alternative antibody of myasthenia gravis (MG) (muscle-specific receptor tyrosine kinase) is indicated when all tests are negative.

 

See Myasthenia Gravis/Lambert Eaton Syndrome Diagnostic Algorithm in Special Instructions.

Method Name

CCN, CCPQ, ARBI, ARMO, GANG: Radioimmunoassay (RIA)

STR: Enzyme Immunoassay (EIA)

Reporting Name

MG/LES Evaluation

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)

 

N-TYPE CALCIUM CHANNEL ANTIBODY

≤0.03 nmol/L

 

P/Q-TYPE CALCIUM CHANNEL ANTIBODY

≤0.02 nmol/L

 

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.

P/Q-type calcium channel antibody; N-type calcium channel antibody: Monday through  Friday; 6 a.m

Analytic Time

3 days

Performing Laboratory

Mayo Medical Laboratories in Rochester

CPT Code Information

83519-ACh receptor (muscle) binding antibody

83519-ACh receptor (muscle) modulating antibodies

83519-P/Q-type calcium channel antibody

83519-N-type calcium channel antibody

83520-Striational (striated muscle) antibodies

83519-AChR ganglionic neuronal antibody (if appropriate)

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

LOINC Code Information

Test ID Test Order Name Order LOINC Value
MGL1 MG/LES Evaluation 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
81184 N-Type Calcium Channel Ab 33979-6
81185 P/Q-Type Calcium Channel Ab 33980-4
8746 Striational (Striated Muscle) Ab, S 8097-8
34273 MG Lambert-Eaton Interpretation, S 69048-7

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)