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HelpTest Code LAB2056 RNA Polymerase III Antibodies, IgG, Serum
Additional Codes
RNAP
Useful For
Evaluating patients suspected of having systemic sclerosis as part of systemic sclerosis criteria antibody tests
Providing diagnostic and prognostic information in patients with systemic sclerosis
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
SerumSpecimen Required
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 0.3 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
Specimen Minimum Volume
See Specimen Required
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 21 days | |
| Frozen | 21 days |
On-campus collections: Tube to 99 or deliver to University Extension Hospital Room EH318
Off-campus collections: Centrifuge and aliquot within 2 hours. Specimen to be stored/transported Refrigerated.
Reference Values
<20.0 U (negative)
20.0-39.9 U (weak positive)
40.0-80.0 U (moderate positive)
>80.0 U (strong positive)
Day(s) Performed
Tuesday, Thursday
CPT Code Information
83516
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| RNAP | RNA Polymerase III Ab, IgG, S | 79182-2 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| RNAP | RNA Polymerase III Ab, IgG, S | 79182-2 |
Interpretation
A positive result for RNA polymerase III antibody may support a diagnosis of systemic sclerosis (SSc) in the appropriate clinical context. Anti-RNA polymerase III autoantibody in patients with SSc is associated with the diffuse cutaneous form of disease and an increased risk of sclerodermal renal crisis.
A negative result indicates no detectable IgG antibodies to RNA polymerase III and does not rule out a diagnosis of SSc. The RNA polymerase III IgG enzyme-linked immunosorbent assay tests only for the RP155 dominant epitope, other epitopes in the antigenic complex are absent and cannot be detected.(6) The overall pooled prevalence of anti-RNA polymerase III antibody is reported to be 11%, 95% CI: 8 to 14, range of 0% to 41% in published studies.(4)
Method Description
The immunodominant fragment of RNA polymerase III antigen is derived from recombinant DNA technology. Purified RNA polymerase III antigen is adsorbed to the wells of a polystyrene microtiter plate under conditions that preserve the antigen in its antigenic state. Prediluted controls and diluted patient sera are added to separate wells. Unbound sample is washed away, and an enzyme-labeled antihuman IgG conjugate is added to each well. After incubation and washing away of unbound enzyme-labeled antihuman IgG, the bound conjugate is measured by adding a chromogenic substrate. The intensity of the absorbance produced is measured with an automated microwell plate reader. Results are calculated by comparison to a single-point calibrator.(Package insert: QUANTA Lite RNA Pol III. INOVA Diagnostics; 05/2019)
Report Available
2 to 7 daysSpecimen Retention Time
14 daysReject Due To
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | OK |
| Heat-treated specimen | Reject |
Method Name
Enzyme-Linked Immunosorbent Assay (ELISA)