Summary
| Direction in ME/CFS | ↕ Inconsistent — reported as both higher and lower across studies, with no consistent direction |
|---|---|
| Category | Inflammatory |
| Also described as | Acute phase protein |
| Compared against | HC (healthy controls) |
| Associated symptoms | Low-grade inflammation |
| Test type | Blood test (serum / plasma / whole blood) |
| LOINC code | 1988-5 |
| Source | Strawbridge et al. 2019 — doi:10.1016/j.psyneuen.2019.06.019 |
| Condition atlas | ME/CFS 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
- CRP in Osteoarthritis — ↑ elevated vs OA vs healthy (elevated but less than RA)
- CRP in Rheumatoid Arthritis — ↑ elevated vs RA vs healthy (acute phase reactant, classification criterion)
See the cross-condition hub: CRP across conditions.
Trials, interventions and tests
In clinical-trial registrations this marker maps to the outcome term C-Reactive Protein (21 registered trials use a matching outcome measure).
Clinical trials using C-Reactive Protein (CRP) as an outcome
- NCT06142253: Water-based Activity to Enhance Recovery in Long COVID-19 (Recruiting)
Outcome measure: Change in Blood labs - NCT06597396: Study to Investigate the Efficacy of Abrocitinib in Adult Participants With Severe Fatigue From Post COVID Condition/Long COVID (Active Not Recruiting)
Outcome measure: The difference in blood high sensitivity C-reactive protein (HSCRP) from baseline visit to Day 84 - NCT06437223: Study of Xiflam™ Treatment in Patients Post COVID-19 Infection Suffering From What is Known as Long COVID (LC) (Completed)
Outcome measure: Secondary Endpoint - NCT07285707: Acupuncture and Chinese Herbal Medicine for Long COVID (Recruiting)
Outcome measure: Change in Laboratory Biomarkers - C-reactive protein - NCT05877508: Anti-SARS-CoV-2 Monoclonal Antibodies for Long COVID (COVID-19) (Active Not Recruiting)
Outcome measure: C-Reactive Protein (CRP) - NCT05524532: Effects of Immulina TM Supplements With PASC Patients (Completed)
Outcome measure: Plasma CRP (C-Reactive Protein, ng/mL) - NCT05836402: Long COVID-19 Syndrome Lifestyle Intervention Study (Completed)
Outcome measure: Improvement of long-COVID syndrome signs: Measures of inflammation - NCT06967428: Effect of Metabolic Modulation on a Post-acute COVID-19 Vaccination Syndrome (PACVS) Cohort (Not Yet Recruiting)
Outcome measure: C-Reactive Protein
13 more trials reference this marker.
Interventions studied alongside this marker
Hypothesis-generating links from trial outcome usage and literature co-occurrence. Not treatment recommendations.
- Coenzyme Q10 — 2 trials, 6 PubMed co-citations
e.g. Effects of Coenzyme Q10 on Lipid, Glycemic, and Inflammatory Markers in Metabolic Disorders: A Systematic… - Exercise therapy — 2 trials, 6 PubMed co-citations
e.g. Management of pericarditis: recent advances. - Abrocitinib — 1 trial, 1 PubMed co-citations
e.g. Durability of Response to Abrocitinib in Patients with Moderate-to-Severe Atopic Dermatitis After Treatment… - Acupuncture — 1 trial, 6 PubMed co-citations
e.g. Finegoldia magna Infection in the Lumbar Intervertebral Disc Following Acupuncture with Cupping: A Rare Case… - Low Carbohydrate Diet Intervention — 1 trial, 1 PubMed co-citations
e.g. [The effects of a very low carbohydrate diet intervention on improving cardiovascular risk factors in obese… - Vitamin K2 — 1 trial, 6 PubMed co-citations
e.g. Potential Cardioprotective Role of Menaquinone-4 Against Cardiac Ischemia-reperfusion Injury. - Vitamin D — 1 trial, 6 PubMed co-citations
e.g. Prune Consumption and Bone Health in Older Men: A One-Year Randomized Controlled Trial. - Endurance Training — 1 trial, 6 PubMed co-citations
e.g. Resilience against exercise-related coronary atherosclerosis: A case study in a master athlete participating…
Commercial test availability
C-Reactive Protein (CRP) — commercial laboratory test.
Links are for reference only; availability, specimen requirements and coverage vary by location.
Related Inflammatory markers in ME/CFS
- Interleukin-10 (IL-10) ↕
- Leptin ↑
- Interleukin-8 (IL-8 / CXCL8) ↕
- Resistin ↕
- Interleukin-6 (IL-6) ↕
- Tumor Necrosis Factor-α (TNF-α) ↕
- Transforming Growth Factor-β (TGF-β) ↑
- Interleukin-1 (IL-1α/β) ↑
Full list: ME/CFS Biomarker Atlas.
Frequently asked questions
Is C-Reactive Protein (CRP) high or low in ME/CFS?
Mixed. Some studies report higher and others lower C-Reactive Protein (CRP) in ME/CFS compared with healthy controls, so no single direction is established. Source: Strawbridge et al. 2019.
What symptoms is C-Reactive Protein (CRP) associated with in ME/CFS?
The cited literature associates this marker with Low-grade inflammation. These are population-level associations and do not mean the marker causes the symptoms.
Which test measures C-Reactive Protein (CRP)?
It is measured as a blood test (serum / plasma / whole blood). The standard laboratory code is LOINC 1988-5. Commercial laboratories such as Quest Diagnostics, LabCorp, Ulta Lab Tests list an orderable assay.
Is one abnormal C-Reactive Protein (CRP) result diagnostic of ME/CFS?
No. No single biomarker is diagnostic of ME/CFS. C-Reactive Protein (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 C-Reactive Protein (CRP) specific to ME/CFS?
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, Major Depressive Disorder, Osteoarthritis, Rheumatoid Arthritis 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: 2026-06-29 · Page generated from me-cfs.json · Browse: ME/CFS 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.