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.

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 highly specific (greater than 90 percent) for systemic lupus erythematosus (SLE) but only occurs in 30-35 percent of SLE cases. The presence of antibodies to Smith has variable associations with SLE clinical manifestations.

Compliance Category

FDA

Note

Hotline History

N/A

CPT Codes

86235

Components

Component Test Code* Component Chart Name LOINC
0050085 Smith (ENA) Antibody, IgG 18323-6
* 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

  • Anti-Sm
  • Anti-Smith (ENA) Antibody
  • Sm antibody IgG
  • Sm/RNP
Smith (ENA) Antibody, IgG