The information in this website is intended only for healthcare professionals. By entering this site, you are confirming that you are a healthcare professional.
The information in this website is intended only for laboratory professionals. By entering this site, you are confirming that you are a laboratory professional.
Rheumatoid Arthritis
While many treatments exist for RA, early identification of symptoms and diagnosis may be an even better approach to preventing the development of joint erosion and delaying disease progression. In fact, RA may be considered a potentially curable condition if identified and treated before it fully evolves from inflammatory arthritis to established disease.1 A clinical history and examination are chief to identifying RA, with imaging and laboratory tests providing additional specificity that can help you diagnose patients and begin treatment earlier.1,2
The 2010 American College of Rheumatology/European League Against Rheumatism collaborative initiative classification criteria are based on clinical presentation of synovitis (joint swelling), serology, acute-phase reactants, and duration of symptoms. Once other conditions have been ruled out, a patient is classified as having RA if a score of ≥6 out of a possible 10 is reached.3
Joint Distribution (0-5)
1 large joint – 0
2-10 large joints – 1
1-3 small joints (large joints not counted) – 2
4-10 small joints (large joints not counted) - 3
>10 joints (at least one small joint) – 5
Symptom Duration (0-1)
<6 weeks – 0
≥6 weeks – 1
Serology (0-3)
Negative RF AND negative CCP – 0
Low positive RF OR low positive CCP – 2
High positive RF OR high positive CCP – 3
Acute Phase Reactants (0-1)
Normal CRP AND normal ESR - 0
Abnormal CRP AND abnormal ESR – 1
A score ≥6 = rheumatoid arthritis3
Who Should Be Tested
- Patients suspected of having RA
- Patients requiring differential diagnosis of RA from osteoarthritis or psoriatic arthritis
Clinical Guidelines to Aid in Diagnosis
Numerous international guidelines recommend RF IgM and anti-CCP as first-line tests to aid in the diagnosis of rheumatoid arthritis. CCP antibodies appear in the early stages of rheumatoid disease.4,5
International guidelines classification criteria also recommend laboratory testing for:
- Erythrocyte Sedimentation Rate (ESR)
- C-Reactive Protein (CRP)
Many tests measure rheumatoid factor (RF) using nephelometry or turbidometry. However, using an RA panel that can distinguish between the different RF isotypes—RF IgA and RF IgM in particular—can give you important additional diagnostic guidance.6-8
Tests Available to Help Aid in the Diagnosis of RA
The EliA™ Rheumatoid arthritis panel offers a full range of automated RF isotypes, including the best-in-class Cyclic Citrullinated Peptide (CCP2) Antibody (IgG) test. Leveraging the exceptional sensitivity and specificity of these tests can provide the early diagnostic guidance needed to potentially improve outcomes for patients with rheumatoid arthritis.
INCREASING TITER, INCREASING NUMBER OF MARKERS 9, 10
EliA RF IgM11
Sample material: Serum, plasma (EDTA, citrate)
Reference Values
| Measuring range: 0.4–200 EliA U/mL |
|
| Value | Classification |
| <3.5 EliA U/ml | Negative |
| 3.5-5 ElA U/ml | Equivocal |
| >5 EliA U/ml | Positive |
EliA RF IgA12
Sample material: Serum, plasma (EDTA, citrate)
Reference Values
| Measuring range: 0.2–214 EliA U/mL |
|
| Value | Classification |
| <14 EliA U/ml | Negative |
| 14-20 ElA U/ml | Equivocal |
| >20 EliA U/ml | Positive |
EliA CCP13
Sample material: Serum, plasma (EDTA, citrate)
Reference Values
| Measuring range: 0.4–340 EliA U/mL |
||
| Value | Classification | |
| <7 EliA U/ml | Negative | |
| 7-10 EliA U/ml | Equivocal | It is recommended to retest patients with equivocal results after 8-12 weeks. |
| <10 EliA U/ml | Positive | |
Reference values apply to all ages. Reference values, coating, dilution and sample material have been taken from respective Phadia 250 instrument Directions for Use. These data are intended as a guide and should be treated accordingly.
If you have any questions or uncertainty please contact us >
- Heidari B. Rheumatoid Arthritis: Early diagnosis and treatment outcomes. Caspian J Intern Med. 2011;2(1):161-170.
- Da Mota LMH, Laurindo I, dos Santos Neto L, et al. Imaging diagnosis of early rheumatoid arthritis. Rev Bras Reumatol. 2012;52(5):757-766
- Aletaha D, Neogi T, Silman AJ. 2010 Rheumatoid arthritis classification criteria: an American College of Rheumatology/European League Against Rheumatism collaborative initiative. Arthritis Rheum. 2010;62:2569-581.
- Schellekens GA, Visser H, de Jong BA, et al. The diagnostic properties of rheumatoid arthritis antibodies recognizing a cyclic citrullinated peptide. Arthritis Rheum. 2000;43(1):155-63.
- Berglin E, Padyukov L, Sundin U, et al. A combination of autoantibodies to cyclic citrullinated peptide (CCP) and HLA-DRB1 locus antigens is strongly associated with future onset of rheumatoid arthritis. Arthritis Res Ther. 2004;6(4): R303–R308.
- Bobbio-Pallavicini F, Caporali R, Alpini C, et al. High IgA rheumatoid factor levels are associated with poor clinical response to tumour necrosis factor α inhibitors in rheumatoid arthritis. Ann Rheum Dis. 2007;66(3):302-307.
- Jónsson T, Valdimarsson H. Is measurement of rheumatoid factor isotypes clinically useful? Ann Rheum Dis. 1993;52(2):161-164.
- Shakiba Y, Koopah S, Jamshidi AR, et al. Anti-cyclic citrullinated peptide antibody and rheumatoid factor isotypes in Iranian patients with rheumatoid arthritis: evaluation of clinical value and association with disease activity. Iran J Allergy Asthma Immunol. 2014;13(3):147-156.
- Halldórsdóttir HD, et al. A prospective study on the incidence of rheumatoid arthritis among people with persistent increase of rheumatoid factor. Ann Rheum Dis. 2000;59:149–151.
- Jaskowski TD Relationship between rheumatoid factor isotypes and IgG anti-cyclic citrullinated peptide antibodies. J Rheumatol. 2010 Aug 1;37(8):1582-8.
- Phadia™ EliA™ RF IgM Directions for Use for the Phadia 250 Laboratory System. Issued April 2017.
- EliA RF IgA Directions for Use for the Phadia 250 Laboratory System. Issued April 2017.
- EliA CCP Directions for Use for the Phadia 250 Laboratory System. Issued March 2017.
© 2023 Thermo Fisher Scientific Inc. All Rights Reserved.