Smith and Smith/RNP (ENA) Antibodies, IgG
Ordering Recommendation
Useful for confirming a diagnosis of systemic lupus erythematosus (SLE) or mixed connective tissue disease (MCTD) following a positive ANA result. Antibodies may be useful in the differential diagnosis of other systemic autoimmune rheumatic diseases such as systemic sclerosis, Sjögren syndrome, polymyositis, dermatomyositis, and overlap syndromes.
Methodology
Semi-Quantitative Enzyme-Linked Immunosorbent Assay/Semi-Quantitative Multiplex Bead Assay
Performed
Sun-Sat
Reported
1-3 days
New York DOH Approval Status
Specimen Required
Serum Separator Tube (SST).
Separate from cells ASAP or within 2 hours of collection. Transfer 1 mL serum to an ARUP Standard Transport Tube. (Min: 0.2 mL)
Refrigerated.
Plasma or other body fluids. Contaminated, hemolyzed, or severely lipemic specimens.
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 |
---|---|---|
Smith/RNP (ENA) Ab, IgG | 19 Units or less | |
Smith (ENA) Antibody, IgG | 40 AU/mL or less |
Interpretive Data
Components | Interpretation |
---|---|
Smith/RNP (ENA) Antibody, IgG | 19 Units or less: Negative 20-39 Units: Weak Positive 40-80 Units: Moderate Positive 81 Units or greater: Strong Positive |
Smith (ENA) Antibody, IgG | 29 AU/mL or less: Negative 30-40 AU/mL: Equivocal 41 AU/mL or greater: Positive |
FDA
Note
Hotline History
Hotline History
CPT Codes
86235 x2
Components
Component Test Code* | Component Chart Name | LOINC |
---|---|---|
0050085 | Smith (ENA) Antibody, IgG | 18323-6 |
0050470 | Smith/RNP (ENA) Ab, IgG | 33983-8 |
Aliases
- Anti-Sm
- Anti-Smith (ENA) Antibody
- Sm antibody IgG
- Sm/RNP
- Sm/RNP Antibody