Ordering Recommendation

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

Mnemonic

RNP

Methodology

Semi-Quantitative Enzyme-Linked Immunosorbent 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: 30 days (avoid repeated freeze/thaw cycles)

Reference Interval

19 Units or less Negative
20-39 Units Weak Positive
40-80 Units Moderate Positive
81 Units or greater Strong 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.

Compliance Category

FDA

Note

An affinity purified RNP/Sm antigen complex is used in this assay.

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