SeroNeg RAdx4 Profile

CPT: 83516(x3); 83520
Updated on 12/23/2022
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Test Includes

14-3-3 eta protein; Anti-CEP1 (citrullinated alpha-enolase 1) Ab; Anti-Sa (citrullinated vimentin) Ab; Anti-CarP (carbamylated protein) Ab

Expected Turnaround Time

7 - 10 days

7 - 10 days

7 - 10 days

7 - 10 days

7 - 10 days

Specimen Requirements




3 mL

Minimum Volume

1.5 mL (Note: This volume does not allow for repeat testing.)


Red-top tube or gel-barrier tube


Separate serum from cells within one hour of collection. Transfer to a plastic transport tube before shipping.

Storage Instructions


Stability Requirements



Room temperature

7 days


14 days


60 days

Freeze/thaw cycles

Stable x1

Causes for Rejection

Grossly hemolyzed; bacterial contamination; lipemic, icteric, non-serum specimen types

Test Details


SeroNeg RAdx4 is a diagnostic and prognostic panel for Rheumatoid Arthritis designed to complement traditional RF and Anti-CCP testing.

This profile, consisting of 14-3-3 eta protein, Anti-CEP1 (citrullinated alphaenolase 1) Ab, Anti-Sa (citrullinated vimentin) Ab, and the novel Anti-CarP (carbamylated protein) Ab, enhances the diagnosis of established or early RA (especially in individuals seronegative for RF and Anti-CCP Ab) and may also help predict disease severity.

Decrease in 14-3-3 eta and/or Anti-Sa Ab with treatment is associated with less radiographic progression. The presence of Anti-CEP1 and Anti-CCP Antibodies suggests the imminent progression of pre-clinical RA into clinical RA. Anti-CarP may predict the development of RA independently of Anti-CCP and may be present years before the onset of symptoms in RA. Anti-CarP may confer a 10% incremental benefit in identify early RA and is associated with more active disease and higher risk of developing joint erosions.


This test was developed and its performance characteristics determined by Labcorp. It has not been cleared or approved by the Food and Drug Administration.


Enzyme-linked immunosorbent assay (ELISA)


Truchetet ME, Dublanc S, Barnetche T, et al. Association of the Presence of Anti- Carbamylated Protein Antibodies in Early Arthritis with a Poorer Clinical and Radiologic Outcome. Arthritis Rheumatol. 2017 Dec;69(12):2292-2302.28853240


Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
520305 SeroNeg RAdx4 Profile 520206 14.3.3 ETA, Rheum. Arthritis ng/mL 75880-5
520305 SeroNeg RAdx4 Profile 520207 Anti-CEP-1 Ab, IgG (RDL) Units 96561-6
520305 SeroNeg RAdx4 Profile 520208 Anti-Sa Ab, IgG (RDL) Units 54022-9
520305 SeroNeg RAdx4 Profile 520317 Anti-CarP Ab Units 66445-8

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