14.3.3 eta, Rheumatoid Arthritis

TEST: 504550
CPT: 83520
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Test Details

Synonyms

  • 14.3.3η Protein ETA
  • Augurex

Use

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.

Limitations

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).

Methodology

Enzyme-linked immunosorbent assay (ELISA)

Reference Interval

<0.2 ng/mL

Additional Information

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

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

Specimen Requirements

Specimen

Serum, frozen

Volume

1 mL

Minimum Volume

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

Container

Red-top tube or gel-barrier tube

Collection

Serum must be separated from cells within 45 minutes of venipuncture. Send serum in a plastic transfer tube.

Storage Instructions

Refrigerate. Stable at room temperature or refrigerated for three days. Frozen for seven days. Freeze/thaw cycles x6.

Causes for Rejection

Hemolysis; lipemia

Clinical Information

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;18:37.26832367
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):2014-2013.25128504
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):R99.24751211

LOINC® Map

Order Code Order Code Name Result Code Result Code Name UofM Result LOINC
504550 14.3.3 ETA, Rheum. Arthritis 504551 14.3.3 ETA, Rheum. Arthritis ng/mL PENDING
504550 14.3.3 ETA, Rheum. Arthritis 504552 14.3.3 ETA, Rheum. Arthritis N/A

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