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Blood Markers Used to Diagnose Rheumatoid Arthritis

Date : 10 Mar, 2017

Rheumatoid arthritis (RA) is a common autoimmune disease estimated to affect roughly one percent of the global population. Approximately 80 percent of people diagnosed with RA will suffer from synovitis (inflammation of the soft synovial joint tissue), cartilage damage and develop bony erosions within one year of diagnosis. Rheumatoid arthritis causes significant loss in work productivity, with up to one-third of those diagnosed unable to work within two years of the onset of RA.

Traditional methods of diagnosing RA rely both on a physical examination and on blood markers that differentiate RA from other autoimmune connective tissue diseases. Research into new blood markers shows promise in providing additional blood tests to help diagnose RA earlier, before symptoms appear; those diagnosed earlier could then be started on drug therapies designed to halt or slow down debilitating disease effects.

The five most common blood markers used to diagnose rheumatoid arthritis

Erythrocyte sedimentation rate (ESR)

The ESR measures general inflammation, and is not specific for RA. It measures the rate at which red cells settle in one hour. The higher the value, the higher the level of inflammation.

C-Reactive protein (CRP)

This blood test also measures the presence and level of inflammation in the body. It, too, is not specific for RA. CRP is a protein produced by the liver that becomes elevated with inflammation.

Rheumatoid Factor (RF)

The rheumatoid factor is an auto-antibody directed against the Fc portion of immunoglobulin found in the blood of about 80 percent of people with rheumatoid arthritis. This is the most common blood test used in diagnosing RA. However, up to 30 percent of those with RA won’t have a positive RF, and it may not be present early in the course of the disease. Other diseases also may show elevated RF levels. There are 2 methods of detection for Rheumatoid Factor (RF) - which include Agglutination tests and Immunoassay methods.

Anti-cyclic citrullinated peptide antibody (anti-CCP)

Citrullination is a normal process that can go awry when specific enzymes and proteins leak out of dying cells and contact the immune system, leading to the production of autoantibodies, i.e. anti-CCPs. This is a newer blood marker that has begun to be widely used to diagnose RA, especially in combination with RF. CCP antibodies are rarely seen in patients who don’t have RA, and so this test was incorporated into the American College of Rheumatology’s revised 2010 criteria for diagnosis of RA.

Protein biomarker 14-3-3eta

This is a blood test for RA based on a protein biomarker known as 14-3-3. Early RA treatment can benefit patients. The 14-3-3η isoform is expressed extracellularly in the joints of patients with rheumatoid arthritis (RA) and expression in both serum and joint fluid correlates strongly with expression of metalloproteinases. 14-3-3η activates pro-inflammatory signaling cascades and inflammatory mediators relevant to the pathogenesis of RA.

Up-regulation of cytokines and chemokines predates the onset of rheumatoid arthritis

A study conducted by Swedish researchers compared donated blood samples before onset of RA symptoms (pre-patient) and after onset with matched control subjects. The plasma levels of 30 cytokines and other markers were measured. Cytokines are a group of proteins that can promote or reduce inflammation. Researchers concluded that those people who later developed RA had “significantly increased levels of several cytokines, cytokine-related factors and chemokines representing the adaptive immune system (Th1, Th2, and Treg cell-related factors).” This study and others like it may help point the way toward development of additional RA-specific blood tests and ultimately, drug therapies based on novel biomarkers.

The article was published as “Up-regulation of cytokines and chemokines predates the onset of rheumatoid arthritis” in Volume 62, Issue 2 – Journal Arthritis & Rheumatology

Transasia offers the ERBA Rheumatoid Factor Kit with the following features.

  • Based on Immunoturbidimetric assay
  • Ready to use liquid stable reagents
  • Liquid stable calibrator traceable to WHO standard material
  • Linearity up to 600 IU/ml
  • Packs available for System pack/Liquid stable and turbilatex kits
  • Application sheets available for all fully and semi-automated analysers

References
http://www.conversantbio.com/blog/bid/355170/5-Blood-Markers-Used-to-Diagnose-Rheumatoid-Arthritis
http://www.ncbi.nlm.nih.gov/pubmed/25365087