Smith (ENA) Antibody, IgG
0050085
Ordering Recommendation
Confirmatory test for systemic lupus erythematosus (SLE) based on ANA results.
Mnemonic
SMITH
Methodology
Semi-Quantitative Multiplex Bead Assay
Performed
Sun-Sat
Reported
1-2 days
New York DOH Approval Status
This test is New York DOH approved.
Submit With Order
Specimen Required
- Patient Preparation
- Collect
- Serum separator tube.
- Specimen Preparation
- Separate serum from cells ASAP or within 2 hours of collection. Transfer 1 mL serum to an ARUP Standard Transport Tube. (Min: 0.2 mL)
- Storage/Transport Temperature
- Refrigerated.
- Unacceptable Conditions
- Plasma or other body fluids. Contaminated, hemolyzed, or severely lipemic specimens.
- Remarks
- Stability
- After separation from cells: Ambient: 48 hours; Refrigerated: 2 weeks; Frozen: 1 year (avoid repeated freeze/thaw cycles)
Reference Interval
29 AU/mL or less | Negative |
30-40 AU/mL | Equivocal |
41 AU/mL or greater | Positive |
Interpretive Data
Smith antibody is very specific for systemic lupus erythematosus (SLE) but only occurs in 30-35% of SLE cases. The presence of antibodies to Smith is often associated with renal disease.
Components
Component Test Code* | Component Chart Name | LOINC |
---|---|---|
0050085 | Smith (ENA) Antibody, IgG | 18323-6 |
Aliases
- Anti-Sm
- Anti-Smith (ENA) Antibody
- Sm antibody IgG
- Sm/RNP