Ordering Recommendation

Secondary diagnostic testing for patients with generalized or ocular myasthenia gravis and no detectable antibodies to acetylcholine receptor (AChR).

Mnemonic

MSK AB

Methodology

Quantitative Radioimmunoassay

Performed

Mon, Thu

Reported

2-8 days

New York DOH Approval Status

This test is New York DOH approved.

Specimen Required

Patient Preparation
Collect

One 4 mL Plain Red or Serum Separator Tube (SST).

Specimen Preparation

Separate from cells ASAP or within 2 hours of collection.  Transfer 2 mL of serum to an ARUP Standard Transport Tube. (Min: 0.5 mL)

Storage/Transport Temperature

Refrigerated.

Unacceptable Conditions

Grossly lipemic, icteric, or hemolyzed specimens.

Remarks
Stability

After separation from cells: Ambient: 48 hours; Refrigerated: 2 weeks; Frozen: 1 month (avoid multiple freeze/thaw cycles)

Reference Interval

Negative 0.00-0.03 nmol/L
Positive 0.04 nmol/L or greater

Interpretive Data

Muscle-specific kinase (MuSK) antibody is found in a subset of patients with myasthenia gravis, primarily those seronegative for muscle acetylcholine receptor (AChR) antibody. Decreasing antibody levels may be associated with therapeutic response; therefore, clinical correlation must be strongly considered. A negative test result does not rule out a diagnosis of myasthenia gravis.

This test was developed and its performance characteristics determined by ARUP Laboratories. It has not been cleared or approved by the US Food and Drug Administration. This test was performed in a CLIA certified laboratory and is intended for clinical purposes.

Compliance Category

Analyte Specific Reagent (ASR)

Note

Hotline History

N/A

CPT Codes

83519

Components

Component Test Code* Component Chart Name LOINC
3001577 Muscle-Specific Kinase (MuSK) Ab, IgG 51716-9
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.

Aliases

  • Muscle-Specific Kinase Antibody by RIA
  • Muscle-Specific Receptor Tyrosine Kinase
  • MuSK
  • MuSK Autoantibody
Muscle-Specific Kinase (MuSK) Antibody, IgG