Anti RNP
Sample: Serum
Schedule: Daily
Units: Titer
Range: Negative
Remarks: RNP antibodies are found in 95-100% of patients with mixed connective tissue disease (MCTD) and is considered specific for this syndrome if other antibodies are negative. RNP antibodies are also found in 20-30% of patients with systemic lupus erythematosus (SLE) and 15% of patients with progressive systemic sclerosis (PSS). Also RNP antibodies may present in other diseases such as MCTD, SS (see SS-A/Ro antibodies and SS-B/La antibodies), and rheumatoid arthritis. Moreover, the presence of RNP antibodies in SLE, in contrast to Sm antibodies, is associated with a relatively benign course and a lower incidence of renal disease. When patients with RNP antibodies develop nephritis, it is usually associated with the presence of antibodies against antigens other than RNP, most notably dsDNA antibodies.
