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HelpCatalog ID RNAP3 RNA Polymerase III Antibody, IgG
Additional Codes
CPOE: Ref RNA Polymerase III Antibody, IgG
DOE: Ref RNA P3
Specimen
Gold SST tube, collect 2.0 mL blood
Centrifuge specimen within 2 hours of collection
Serum, 1.0 mL (0.2 mL minimum), refrigerated
Rejection Criteria
Plasma, CSF, other body fluids, specimens not centrifuged < 2 hours from collection, specimens at room temperature >48 hours, insufficient quantity, unlabelled specimen
Interpretative Information
The presence of RNA polymerase III IgG antibody, when considered in conjunction with other laboratory and clinical findings, is an aid in the diagnosis of systemic sclerosis (SSc) with increased incidence of skin involvement and renal crisis with the diffuse cutaneous form of SSc. RNA polymerase III IgG antibody occur in about 11-23 percent of SSc patients, and typically in the absence of anti-centromere and anti-Scl-70 antibodies.
A negative result indicates no detectable IgG antibodies to the dominant antigen of RNA polymerase III and does not rule out the possibility of SSc. False-positive results may also occur due to non-specific binding of immune complexes. Strong clinical correlation is recommended.
If clinical suspicion remains, consider additional testing for other antibodies associated with SSc, including centromere, Scl-70, U3-RNP, PM/Scl, or Th/To.
Performing Lab
ARUP Laboratories
Turn-Around-Time
1-4 days (performed on Sundays, Tuesdays, and Thursdays)
Reference Values
| 19 Units or less | Negative |
| 20-39 Units | Weak Positive |
| 40-80 Units | Moderate Positive |
| 81 Units or greater | Strong Positive |