Summary
| Direction in Rheumatoid Arthritis | ↑ Elevated — higher than in the comparison group |
|---|---|
| Category | Inflammatory |
| Compared against | RA vs healthy (acute phase reactant, classification criterion) |
| Test type | Blood test (serum / plasma / whole blood) |
| LOINC code | 1988-5 |
| Source | Kourilovitch et al. 2014 — doi:10.1016/j.jaut.2014.01.027 |
| Condition atlas | Rheumatoid Arthritis Biomarker Atlas |
Other conditions where CRP is reported
- CRP in Atrial Fibrillation — ↑ elevated vs AF vs normal population
- CRP in COPD — ↑ elevated vs smokers/COPD vs non-smokers
- C-Reactive Protein (CRP) in Gulf War Illness — ↑ elevated vs HGV
- CRP in Inflammatory Bowel Disease (Crohn's/UC) — ↑ elevated vs active/moderate-to-severe IBD vs symptomatic remission
- C-Reactive Protein (CRP) in Long COVID — ↑ elevated vs HC, R
- CRP in Low Back Pain — ↑ elevated vs nonspecific LBP vs healthy (association evidence)
- C-Reactive Protein (CRP) in Lyme Disease — ↕ inconsistent vs HC
- CRP in Major Depressive Disorder — ↑ elevated vs females with depression vs healthy female controls
- C-Reactive Protein (CRP) in ME/CFS — ↕ inconsistent vs HC
- CRP in Osteoarthritis — ↑ elevated vs OA vs healthy (elevated but less than RA)
See the cross-condition hub: CRP across conditions.
Related Inflammatory markers in Rheumatoid Arthritis
Full list: Rheumatoid Arthritis Biomarker Atlas.
Frequently asked questions
Is CRP high or low in Rheumatoid Arthritis?
Elevated. Studies summarised in the OSMF atlas report higher CRP in Rheumatoid Arthritis than in the reference group of the cited comparison (RA vs healthy (acute phase reactant, classification criterion)). Source: Kourilovitch et al. 2014.
Which test measures CRP?
It is measured as a blood test (serum / plasma / whole blood). The standard laboratory code is LOINC 1988-5. Many of the cited studies used research-grade assays, so clinical availability may vary.
Is one abnormal CRP result diagnostic of Rheumatoid Arthritis?
No. No single biomarker is diagnostic of Rheumatoid Arthritis. CRP findings come from group comparisons, overlap considerably between patients and controls, and vary with study design, timing and comparison group. A result should be interpreted by a clinician alongside symptoms, history and other tests.
Is CRP specific to Rheumatoid Arthritis?
No. The same marker is also reported in Atrial Fibrillation, COPD, Gulf War Illness, Inflammatory Bowel Disease (Crohn's/UC), Long COVID, Low Back Pain, Lyme Disease, ME/CFS, Major Depressive Disorder, Osteoarthritis in this atlas, so it reflects shared biology (for example inflammation or vascular stress) rather than a condition-specific signature.
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Last reviewed: 2026-07-03 · Page generated from rheumatoid-arthritis.json · Browse: Rheumatoid Arthritis atlas · Biomarker Index · All marker pages
Disclaimer: This page is an educational synthesis of published, peer-reviewed research and is not medical advice. Biomarker findings vary across studies with case definitions, comparison groups, timing and assay methods. Direction of change reflects the predominant finding in the cited source and does not establish a diagnostic threshold. Discuss any test result with a qualified clinician.