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Smith/RNP (ENA) Antibody, IgG
0050470
Ordering Recommendation

Useful in the differential diagnosis of connective tissue diseases with or without myopathy.

Mnemonic
RNP
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
ARUP Consult®
Disease Topics
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 lessNegative
30-40 AU/mLEquivocal
41 AU/mL or greaterPositive

Interpretive Data
Smith/RNP antibodies are frequently seen in patients with mixed connective tissue disease (MCTD) and are also associated with other systemic autoimmune rheumatic diseases (SARDs) such as systemic lupus erythematosus (SLE), systemic sclerosis, and myositis. Antibodies targeting the Smith/RNP antigenic complex also recognize Smith antigens, therefore, the Smith antibody response must be considered when interpreting these results.

Note
Purified Smith/RNP antigen is used in this assay. U1RNP IgG antibodies detected using immunoassays that employ recombinant U1-70K, A, and C proteins may yield discrepant results.
Hotline History
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Components
Component Test Code*Component Chart NameLOINC
0050470Smith/RNP (ENA) Ab, IgG33983-8
* 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
  • Ribonucleoproteins
  • RNP