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.
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

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.

No compliance statements are in use for this test.

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
N/A
CPT Codes

86235

Components
Component Test Code* Component Chart Name LOINC
0050470 Smith/RNP (ENA) Ab, IgG 33983-8
* 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
Smith/RNP (ENA) Antibody, IgG