Useful in the differential diagnosis of connective tissue diseases with or without myopathy.
Semi-Quantitative Multiplex Bead Assay
Serum separator tube.
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)
Plasma or other body fluids. Contaminated, hemolyzed, or severely lipemic specimens.
After separation from cells: Ambient: 48 hours; Refrigerated: 2 weeks; Frozen: 1 year (avoid repeated freeze/thaw cycles)
|29 AU/mL or less||Negative|
|41 AU/mL or greater||Positive|
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.
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.
|Component Test Code*||Component Chart Name||LOINC|
|0050470||Smith/RNP (ENA) Ab, IgG||33983-8|