RNA Polymerase III Ab, IgG
Label Mnemonic: RNAP
Epic Lab Code: LAB7425
Downtime Form: A-1a Miscellaneous Request
Commercial Mail-out Laboratory
5231 RCP
356-8593
Specimen(s):
Serum
Collection Medium:
Red top tube 5 mL (Clot Activator)
Minimum:
0.5 mL serum in a red top tube
Rejection Criteria:
Gross Hemolysis, Gross Lipemia
Turn Around Time:
2 working days upon receipt at reference laboratory
Reference Range:
<20.0 U (negative)
20.0-39.9 U (weak positive)
40.0-80.0 U (moderate positive)
>80.0 U (strong positive)
Interpretive Data:
A positive result supports a possible diagnosis of systemic sclerosis (see Comments). This autoantibody is strongly associated with diffuse cutaneous scleroderma and with an increased risk of acute renal crisis.

A negative result indicates no detectable IgG antibodies to RNA polymerase III, but does not rule out the possibility of systemic sclerosis (11%-23% sensitivity).
Comments:
Cautions:
A positive result indicates the presence of measurable IgG antibodies to RNA polymerase III, but does not unequivocally establish the diagnosis of systemic sclerosis or other autoimmune disease.

The level of RNA polymerase III autoantibodies does not indicate the severity of disease in patients with systemic sclerosis.

The presence of immune complexes or other immunoglobulin aggregates in the patient specimen may cause an increased level of nonspecific binding and produce false-positive results with this assay.
Methodology:
Enzyme-Linked Immunosorbent Assay (ELISA)
CPT Code:
83520