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RNA Polymerase III Antibody, IgG
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Ordering Recommendation
First-line test for the evaluation of systemic sclerosis, or connective tissue disease with renal or cutaneous involvement. Preferred test is Comprehensive Systemic Sclerosis Panel (3000480).
Mnemonic
Methodology
Semi-Quantitative Enzyme-Linked Immunosorbent Assay
Performed
Sun, Tue, Thu
Reported
1-4 days
New York DOH Approval Status
Specimen Required
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)
Refrigerated.
After separation from cells: Ambient: 48 hours; Refrigerated: 2 weeks; Frozen: 1 year
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
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.
FDA
Note
Hotline History
CPT Codes
83516
Components
| Component Test Code* | Component Chart Name | LOINC |
|---|---|---|
| 2001602 | RNA Polymerase III Antibody, IgG | 79182-2 |
Aliases
- RNA pol 3
- RNA Pol III IgG
- RNA Polymerase III Ab
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