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Test Code ETAPROTEIN 14.3.3 eta, Rheumatoid Arthritis

Methodology

Enzyme-linked immunosorbent assay (ELISA)

This test was developed, and its performance characteristics determined, by LabCorp. It has not been cleared or approved by the US Food and Drug Administration (FDA).

Performing Laboratory

LabCorp Burlington, NC

Specimen Required

Container/Tube: Gold top tube

Specimen: 1 mL serum ( 0.5 mL min)

Transport Temperature: Frozen

Stability:  Room Temperature and Refrigerated  3 Days

                 Frozen  7 Days

 

Causes for Rejection       Hemolysis; lipemia

Reference Values

< 0.2  ng/mL

Test Classification and CPT Coding

83520

 

Loinc Code: 75880-5

Conputer Interface Code

PDM #  1859784

Used For

14-3-3 eta protein is a joint-derived, proinflammatory mediator that is implicated in the joint erosion process and pathogenesis of RA. Serum 14-3-3 eta is elevated in both early and established RA.

 

14-3-3 eta is highly specific for RA. Serum 14-3-3 eta may be especially helpful in identifying patients with early RA where it provides a 15% incremental benefit to the diagnostic sensitivity of markers, Rheumatoid Arthritis (RA) Factor and Cyclic Citrullinated Peptide (CCP) Antibodies.1 See table.

Diagnostic sensitivity: Complementarity between diagnostic markers (14-3-3η, RF and anti-CCP) in patients with early and established RA. Table 3A2

Marker Positivity

 

Early RA

 

Established RA

RF+

 

57

 

85

Anti-CCP+

 

59

 

79

14-3-3η+

 

64

 

77

Anti-CCP and RF+

 

72

 

88

14-3-3η+ and RF+

 

75

 

94

14-3-3η+ and anti-CCP+

 

72

 

96

14-3-3η+ and RF+ and anti-CCP+

 

78

 

96

Diagnostic sensitivity: Complementarity between diagnostic markers (14-3-3η, RF and anti-CCP) in patients with early and established RA. Table 3A2

RF: rheumatoid factor, anti-CCP: anticitrullinated protein antibodies, RA: rheumatoid arthritis

Marker Positivity

Early RA

Established RA

RF+

57

85

Anti-CCP+

59

79

14-3-3η+

64

77

Anti-CCP and RF+

72

88

14-3-3η+ and RF+

75

94

14-3-3η+ and anti-CCP+

72

96

14-3-3η+ and RF+ and anti-CCP+

78

96

Positive serum 14-3-3 eta levels are associated with higher rates of joint damage as measured by radiographic assessments (Sharp/van der Heijde Score).3

Footnotes

1. Carrier N, Marotta A, de Brum Fernandes AJ, et al. Serum levels of 14-3-3η protein supplement C-reactive protein and rheumatoid arthritis-associated antibodies to predict clinical and radiographic outcomes in a prospective cohort of patients with recent-onset inflammatory polyarthritis. Arthritis Res Ther. 2016 Feb;18:37. PubMed 26832367

2. Maksymowych WP, Naides SJ, Bykerk V, et al. Serum 14-3-3η is a novel marker that complements current serological measurements to enhance detection of patients with rheumatoid arthritis. J Rheumatol. 2014 Nov; 41(11):2014-2013. PubMed 25128504

3. Maysymowych WP, van der Heijde D, Allaart CF, et al. 14-3-3η is a novel mediator associated with the pathogenesis of rheumatoid arthritis and joint damage. Arthritis Res Ther. 2014 Apr;16(2):R99. PubMed 24751211