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Sm and Sm/RNP Antibodies

Test Code

7448

CPT Code(s)

86235 (x2)

Preferred Specimen(s)

1 mL serum

Minimum Volume

0.5 mL

Transport Container

Plastic screw-cap vial

Transport Temperature

Room temperature

Specimen Stability

Room temperature: 4 days
Refrigerated: 7 days
Frozen: 30 days

Reject Criteria

Gross hemolysis • Hyperlipemic • Grossly icteric

Methodology

Immunoassay (IA)

Performing Laboratory

Quest Diagnostics-Miami
10200 Commerce Parkway
Miramar, FL 33025-3938

Reference Range(s)

Sm Antibody  <1.0 AI Negative
Sm/RNP Antibody  <1.0 AI Negative 

Clinical Significance

Antibodies to Sm are highly specific for systemic lupus erythematosus (SLE) and when present are considered a marker antibody. However, these antibodies are found in only 20% of patients with SLE. RNP antibodies (also known as anti-u1 or ribonucleoprotein antibodies) are found in 45% of SLE patients but are also observed in numerous other disease states such as Sjögren's syndrome, scleroderma and polymyositis. Elevated levels of antibodies to RNP are seen in mixed connective tissue disease. In SLE, RNP antibodies have been associated with a relatively benign disease course with lower incidence of renal and central nervous system involvement. Patients may be considered positive for RNP antibodies when the RNP antibody result is significantly higher than the Sm antibody result.

Alternative Name(s)

Anti-Ribonucleic Protein Antigen, Anti-ENA Antibody, ENA Antibodies, Anti-Smith Antibody, Ribonuclear Protein Antibody, RNP Antibody

LOINC®' Code(s)

The Result and LOINC information listed below should not be used for electronic interface maintenance with Quest Diagnostics. Please contact the Quest Diagnostics Connectivity Help Desk for more information at 800-697-9302.

NOTE: The codes listed in the table below are not orderable Test Codes.

Result
Code
Result NameLOINC CodeComponent Name
45061025SM ANTIBODY43182-5Smith extractable nuclear Ab
45061030SM/RNP ANTIBODY14030-1Smith extractable nuclear Ab+Ribonucleoprotein extractable nuclear Ab

Reference ranges are provided as general guidance only. To interpret test results use the reference range in the laboratory report.

The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.

LOINC assignment is based on a combination of test attributes, including the method used by the performing laboratory. For tests not performed by Quest Diagnostics, codes are assigned by the performing laboratory.

* The tests listed by specialist are a select group of tests offered. For a complete list of Quest Diagnostics tests, please refer to our Directory of Services.