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ANA Sm and Sm/RNP Antibodies

CPT/HCPCS 86235x2
Order Code CH275
Turnaround Time 48-72 hrs
Specimen Requirements
Specimen Source
Serum
Transport Container
(Specimen Container)

Transport Tube

Preferred Specimens
1 mL Serum
Minimum Volume (uL)
0.5 mL
Collection Instructions
(Transport Temperature)
Room Temperature
Specimen Stability
Temperature Period
Room temperature 4 days
Refrigerated 7 days
Frozen 30 days
Reject Criteria

Gross hemolysis, Grossly lipemic, Grossly icteric

Test Details
Methodology
Immunoassay
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.

Reference Ranges

<1.0 AI Negative