ARUP's Laboratory Test Directory

RNP (U1) (Ribonucleic Protein) (ENA) Antibody, IgG : 0050470

Mnemonic: RNP

Methodology: Semi-Quantitative Multiplex Bead Assay
Performed: Sun-Sat
Reported: 1-2 days
Specimen Required: 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.

Stability (collection to initiation of testing): 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% of mixed connective tissue disease and is considered specific for this syndrome if other antibodies are negative; RNP is also present in 20-30% of systemic lupus erythematosus and 15-25% of progressive systemic sclerosis.
Note: RNP antigens also contain epitopes which are immunologically identical to free Smith antigens.  The Smith antibody response must be considered when interpreting RNP results.
CPT Code(s): 86235
Cross References: Anti-RNP (ENA) Antibody (RNP (U1) (Ribonucleic Protein) (ENA) Antibody, IgG), Sm/RNP Antibody (RNP (U1) (Ribonucleic Protein) (ENA) Antibody, IgG), U1 RNP (RNP (U1) (Ribonucleic Protein) (ENA) Antibody, IgG)