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).


Semi-Quantitative Enzyme-Linked Immunosorbent Assay


Sun, Tue, Thu


1-4 days

New York DOH Approval Status

This test is New York DOH approved.

Specimen Required

Patient Preparation

Serum separator tube.

Specimen Preparation

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)

Storage/Transport Temperature


Unacceptable Conditions

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.

Compliance Category



Hotline History


CPT Codes



Component Test Code* Component Chart Name LOINC
2001602 RNA Polymerase III Antibody, IgG 79182-2
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.


  • RNA pol 3
  • RNA Pol III IgG
  • RNA Polymerase III Ab
RNA Polymerase III Antibody, IgG