RNP (U1) (Ribonucleic Protein) (ENA) Antibody, IgG
0050470
Ordering Recommendation
May be useful in the evaluation of neuropsychiatric SLE, positive predictive value is variable.
Submit With Order
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.
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
RNP antibody is seen in 95-100 percent of mixed connective tissue disease and is considered specific for this syndrome if other antibodies are negative; RNP is also present in 20-30 percent of systemic lupus erythematosus and 15-25 percent of progressive systemic sclerosis. RNP antigens also contain epitopes that are immunologically identical to free Smith antigens, therefore, the Smith antibody response must be considered when interpreting RNP results..
Note
CPT Code(s)
86235
Components
Component Test Code*Component Chart Name
0050470Ribonucleic Protein (U1) (ENA) Ab, IgG
* 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.
Cross References
  • Anti U1RNP
  • Anti-Ribonuclear Protein
  • Anti-RNP (ENA) Antibody
  • Sm/RNP Antibody
  • U1 RNP