Acetylcholine Receptor Binding Antibody with reflex to Muscle-Specific Kinase (MuSK) Ab, IgG

3001868
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Additional Technical Information

Ordering Recommendation

Initial diagnostic test when suspicion of myasthenia gravis is high.

Mnemonic

ACHR BIN R

Methodology

Quantitative Radioimmunoassay

Performed

Sun-Sat

Reported

2-8 days

New York DOH Approval Status

This test is New York DOH approved.

Specimen Required

Patient Preparation
Collect

Serum Separator Tube (SST).

Specimen Preparation

Separate from cells ASAP or within 2 hours of collection. Transfer 0.5 mL serum to an ARUP Standard Transport Tube. (Min: 0.3 mL)

Storage/Transport Temperature

Refrigerated.

Unacceptable Conditions

Plasma. Contaminated, hemolyzed, or severely lipemic specimens.

Remarks
Stability

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

Reference Interval

Test Number
 Components
 Reference Interval
0080009 Acetylcholine Receptor Binding Antibody
Negative 0.0-0.4 nmol/L
Positive 0.5 nmol/L or greater

3001576 Muscle-Specific Kinase (MuSK) Antibody, IgG
Negative 0.00-0.03 nmol/L
Positive 0.04 nmol/L or greater

Interpretive Data

Approximately 85-90 percent of patients with myasthenia gravis (MG) express antibodies to the acetylcholine receptor (AChR), which can be divided into binding, blocking, and modulating antibodies. Binding antibody can activate complement and lead to loss of AChR. Blocking antibody may impair binding of acetylcholine to the receptor, leading to poor muscle contraction. Modulating antibody causes receptor endocytosis resulting in loss of AChR expression, which correlates most closely with clinical severity of disease. Approximately 10-15 percent of individuals with confirmed myasthenia gravis have no measurable binding, blocking, or modulating antibodies.

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

Laboratory Developed Test (LDT)

Note

If Acetylcholine Receptor Binding Antibody result is less than or equal to 0.4 nmol/L then Muscle-Specific Kinase (MuSK) Ab, IgG (ARUP test code 3001576) will be added. Additional charges apply.

Hotline History

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Hotline History

Date of Change
Test Name Change
Methodology
Performance/Reported Schedule
Specimen Requirements
Reference Interval
Interpretive Data
Note
CPT Code
Component Change
Other Interface Change
New Test
Inactive
08/19/2019
X
N/A

CPT Codes

83519; if reflexed, add 83519

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Components

Component Test Code* Component Chart Name LOINC
0080009 Acetylcholine Binding Antibody 11034-6
* 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

  • AChR Antibody
  • ACHR blocking antibody
  • Muscle nicotinic Acetylcholine Receptor (AChR) Binding Antibody
  • Muscle-Specific Kinase Antibody by RIA
  • Muscle-Specific Receptor Tyrosine Kinase
  • MuSK
  • MuSK Autoantibody
  • Myasthenia Gravis Antibodies
Acetylcholine Receptor Binding Antibody with reflex to Muscle-Specific Kinase (MuSK) Ab, IgG