Ordering Recommendation

Acceptable reflexive panel for the differential diagnosis of acquired neuromuscular junction disorders. Panel includes acetylcholine receptor binding, blocking, and modulating antibodies; ganglionic acetylcholine receptor antibodies; P/Q-type and N-type voltage-gated calcium channels; voltage-gated potassium channels; titin antibody; striated muscle antibodies; and leucine-rich glioma-inactivated protein 1 antibody and contactin-associated protein-2 antibody IgG with reflex to titers.

Mnemonic

MUWA R2

Methodology

Quantitative Radioimmunoassay/Qualitative Radiobinding Assay/Semi-Quantitative Flow Cytometry/Semi-Quantitative Indirect Fluorescent Antibody

Performed

Refer to individual components

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 serum from cells ASAP or within 2 hours of collection. Transport 2 mL serum. (Min: 1 mL)

Storage/Transport Temperature

Refrigerated.

Unacceptable Conditions

Plasma. Contaminated, hemolyzed, or severely lipemic specimens.

Remarks
Stability

Ambient: 48 hours; Refrigerated: 2 weeks; Frozen: 1 year

Reference Interval

Test Number
Components
Reference Interval
  Striated Muscle Antibodies, IgG Screen Less than 1:40
  Acetylcholine Binding Antibody 0.4 nmol/L or less
  P/Q-Type Calcium Channel Antibody 24.5 pmol/L or less
  Acetylcholine Blocking Antibody 26 % blocking or less
  Voltage-Gated Potassium Channel Ab, Ser 31 pmol/L or less
  Titin Antibody 0.45 IV or less
  N-Type Calcium Channel Antibody 69.9 pmol/L or less
  Ganglionic Acetylcholine Receptor Ab 8.4 pmol/L or less

Interpretive Data

Refer to report.


Component Interpretation
Acetylcholine Receptor Binding Antibody 0.0-0.4 nmol/L  Negative
0.5 nmol/L or greater  Positive
Acetylcholine Receptor Blocking Antibody 0-26% blocking  Negative
27-41% blocking  Indeterminate
42% or greater blocking  Positive
P/Q-Type Voltage-Gated Calcium Channel (VGCC) Antibody 0.0 to 24.5 pmol/L  Negative
24.6 to 45.6 pmol/L  Indeterminate
45.7 pmol/L or greater  Positive
Voltage-Gated Potassium Channel (VGKC) Antibody, Serum 31 pmol/L or less  Negative
32-87 pmol/L Indeterminate
88 pmol/L or greater  Positive
Titin Antibody 0.00-0.45 IV  Negative
0.46-0.71 IV  Indeterminate
0.72 IV or greater   Positive
N-Type Calcium Channel Antibody 0.0 to 69.9 pmol/L  Negative
70.0 to 110.0 pmol/L  Indeterminate
110.1 pmol/L or greater Positive
Ganglionic Acetylcholine Receptor Antibody 0.0 - 8.4 pmol/L  Negative
8.5 - 11.6 pmol/L  Indeterminate
11.7 pmol/L or greater  Positive

Compliance Category

Laboratory Developed Test (LDT)

Note

If Acetylcholine Receptor Binding Antibody result is greater than 0.4 nmol/L or Acetylcholine Receptor Blocking Antibody result is greater than 26 percent, then Acetylcholine Receptor Modulating Antibody will be added. If Striated Muscle Ab is detected, then a titer will be added. If VGKC is Indeterminate or Positive, LGI1 Antibody IgG and CASPR2 Antibody IgG will be added. If LGI1 antibody IgG is positive, then LGI1 antibody IgG titer will be added. If CASPR2 antibody IgG is positive, then CASPR2 antibody IgG titer will be added. Additional charges apply.

Hotline History

N/A

CPT Codes

83519 x3; 83516 x2; 86255; 86596 x2; if reflexed, add 83516; 86255 x2; 86256 x3

Components

Component Test Code* Component Chart Name LOINC
0050747 Striated Muscle Antibodies, IgG Screen 49692-7
0080009 Acetylcholine Binding Antibody 11034-6
0092629 P/Q-Type Calcium Channel Antibody 33980-4
0099580 Acetylcholine Blocking Antibody 42937-3
2004890 Voltage-Gated Potassium Channel Ab, Ser 41871-5
2005637 Titin Antibody 100371-4
3002047 N-Type Calcium Channel Antibody 33979-6
3003019 Ganglionic Acetylcholine Receptor Ab 42233-7
* 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

Autoimmune Neuromuscular Junction Reflexive Panel