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Laboratory Test Directory



Name Method Department Units
ENA (Sm,RNP) Enzyme-linked immunosorbent assay (ELISA)
CMI, Immunology Units

Battery Members


Specimen Requirements

Serum Spun

Container Type Container Size Specimen Volume

Red tube, (no anticoagulant), No Gel

3 mL 2 mL

Room temperature - 8 hour(s)
Refrigerated - 48 hour(s)
Frozen - indefinite day(s)

Specimen Preparation

  • Allow specimen to clot for one hour at room temperature
  • Centrifuge, remove serum and refrigerate

Reasons for Rejection

  • Plasma unacceptable
  • Frozen whole blood
  • Wrong collection tube
  • Capillary specimen
  • Bacterial contamination
  • Heat treated specimen
  • Gross lipemia
  • Gross hemolysis


Includes Smith and Ribonuclear Protein Antibodies. Positive results are answered with units

A positive result in the RNP ELISA indicates the presence of antibodies reactive with the RNP/Sm complex but cannot distinguish between anti-Sm and anti-RNP activity.

The Sm ELISA is intended for the measurement of Sm antibody activity and is considered a marker for SLE.

If the patient is positive for Sm antibodies, it is very likely that RNP antibodies are also present (it is rare to see anti-Sm in the absence of RNP antibodies). 

If a sample is negative in the Sm ELISA but positive in the RNP ELISA, then the reactivity is largely or exclusively due to RNP antibodies.

For results interpretation, consultation with Rheumatology is suggested.

CPT Code

  • 86235 (x2)