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.
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)
Methodology
Semi-Quantitative Enzyme-Linked Immunosorbent Assay/Semi-Quantitative Multiplex Bead Assay
Performed
Sun-Sat
Reported
1-3 days
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