RNA Polymerase III Ab, IgG
| Label Mnemonic: | RNAP |
| Epic code: | LAB7425 |
| Downtime form: | A-1a Doctor/Provider Orders - Pathology Core and Specialty Care Nursery |
Commercial Mailout Laboratory
6240-8 RCP
356-8593
6240-8 RCP
356-8593
Specimen(s):
Serum
Collection Medium:
 |
| Red top tube 5 mL (Clot Activator) |
Minimum:
Preferred Minimum: 1 mL serum in a red top tube
Absolute Minimum: 0.2 mL serum in a red top tube
Absolute Minimum: 0.2 mL serum in a red top tube
Turn Around
Time:
1-4 days upon receipt at reference laboratory
Reference Range:
19 Units or less (Negative)
20-39 Units (Weak Positive)
40-80 Units (Moderate Positive)
81 Units or greater (Strong Positive)
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.
Clinical Sensitivity
*ANA by IFA for SSc: 90-95%
*Individual SSc-specific marker may vary based on ethnicity
Results
*ANA patterns (including centromere) are reported
*If positive, pattern and titers are reported
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.
Clinical Sensitivity
*ANA by IFA for SSc: 90-95%
*Individual SSc-specific marker may vary based on ethnicity
Results
*ANA patterns (including centromere) are reported
*If positive, pattern and titers are reported
Comments:
Recommended first-line test for the evaluation of systemic sclerosis, or connective tissue disease with renal or cutaneous involvement.
Test
Limitations:
*Negative antibody test result does not exclude SSc (5-10% of patients
with SSc are ANA IFA negative)
*Panel does not include Th/To
with SSc are ANA IFA negative)
*Panel does not include Th/To
Methodology:
Semi-Quantitative Enzyme-Linked Immunosorbent Assay
CPT Code:
83516