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Test Code MG Eval Ped Myasthenia Gravis (MG) Evaluation, Pediatric

Useful For

Recommended for initial investigation of patients presenting at less than age 20 with a defect of neuromuscular transmission


Confirming that a recently acquired neurological disorder has an autoimmune basis


Distinguishing acquired myasthenia gravis from congenital myasthenic syndromes (persistently seronegative)


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

Seattle Children's Hospital Note:

Clinical System Name:  Myasthenia Gravis Evaluation Panel

Profile Information

Test ID Reporting Name Available Separately Always Performed
MGEPI MG Pediatric Interpretation, S No Yes
ARBI ACh Receptor (Muscle) Binding Ab Yes Yes
ARMO ACh Receptor (Muscle) Modulating Ab No Yes

Testing Algorithm

See Myasthenia Gravis: Pediatric Diagnostic Algorithm in Special Instructions.

Method Name

Radioimmunoassay (RIA)

Reporting Name

MG Eval, Pediatric

Specimen Type


Specimen Required


Preferred: Red top

Acceptable: Serum gel

Specimen Volume: 2 mL

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

Specimen Minimum Volume

1.5 mL

Specimen Stability Information

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

Reject Due To


Mild OK; Gross reject


Mild OK; Gross reject


Mild OK; Gross reject



Reference Values


≤0.02 nmol/L



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

Method Description

Muscle acetylcholine receptor (AChR) binding (IgG and IgM) are measured quantitatively by immunoprecipitation assays. The high-affinity ligand (125)I-alpha-bungarotoxin is complexed with detergent-solubilized muscle AChR prepared from a mixture of innervated and denervated human muscle. AChR modulating antibodies is detected in a bioassay; (125)I-bungarotoxin measures percent loss of AChR from viable, noninnervated, monolayer cultures of human muscle cells following 14-hour incubation with patient's serum.(Griesmann GE, Kryzer TJ, Lennon VA: Autoantibody profiles of myasthenia gravis and Lambert-Eaton myasthenic syndrome. In Manual of Clinical and Laboratory Immunology. Sixth edition. Edited by NR Rose, RG Hamilton, B Detrick. Washington, DC, ASM Press, 2002, pp 1005-1012)

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.

Seattle Children's Hospital Note:

TAT: 5 - 7 days

Performing Laboratory

Mayo Medical Laboratories in Rochester

Test Classification

See individual components

CPT Code Information

83519-ACh receptor (muscle) binding antibody

83519-ACh receptor (muscle) modulating antibodies

LOINC Code Information

Test ID Test Order Name Order LOINC Value
MGP1 MG Eval, Pediatric 53705-0


Result ID Test Result Name Result LOINC Value
8338 ACh Receptor (Muscle) Binding Ab 11034-6
8879 ACh Receptor (Muscle) Modulating Ab 30192-9
34275 MG Pediatric Interpretation, S 69048-7


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