CRP Levels in Myeloproliferative Neoplasms
CRP levels in myeloproliferative neoplasms are often elevated but highly variable, with many MPN patients showing increased levels that reflect the chronic inflammatory state driven by the neoplastic clone, though specific numeric ranges are not well-established in clinical guidelines. 1
Understanding CRP Elevation in MPNs
The inflammatory burden in MPNs is driven by the neoplastic clone itself, which triggers a paracrine secretion of inflammatory cytokines (particularly IL-6 and TNF-alpha) from cells within the tumor microenvironment. 1 This cytokine storm leads to:
- Chronic systemic inflammation that manifests as elevated acute phase reactants including high-sensitivity CRP (hs-CRP) 1
- Constitutional symptoms that negatively impact quality of life 1
- Increased thrombotic risk, as elevated CRP and pentraxin-3 (PTX-3) are linked to both arterial and venous thrombosis 1
- Disease progression and premature atherosclerosis 1
Expected CRP Range
While precise numeric thresholds are not defined in MPN guidelines, the available evidence suggests:
- CRP is frequently elevated in MPN patients, though the degree varies considerably 1
- Levels are typically lower than acute bacterial infections (which show median CRP of 120 mg/L) but can be substantial 2
- Many patients may have CRP <10 mg/L, as approximately 33% of cancer patients overall have values below this threshold 3
- CRP >6.1 mg/L has been associated with poor prognosis in related myeloid disorders (myelodysplastic syndromes), suggesting this may be a clinically relevant threshold 4
Clinical Significance and Prognostic Value
Including inflammatory markers in MPN assessment is important for risk stratification:
- High-sensitivity CRP and PTX-3 plasma levels are often increased in MPN patients and may help identify those with high inflammatory burden 1
- Elevated inflammatory markers can guide decisions about more aggressive therapy, including ruxolitinib or allogeneic stem cell transplantation 1
- The inflammatory profile combined with adverse molecular features helps identify patients who may benefit from curative approaches 1
Important Clinical Caveats
Do not interpret CRP in isolation:
- Multiple non-malignant factors influence CRP levels including age, sex, race, BMI, smoking, diet, sleep, and medications 3
- CRP >10 mg/L does not always indicate acute infection—approximately 20% may be related to smoking and lifestyle factors 2
- Normal or mildly elevated CRP does not exclude significant disease, as one-third of cancer patients have CRP <10 mg/L 3
- Serial measurements are more informative than single values for assessing disease activity and inflammatory burden 1
The key clinical takeaway: CRP elevation in MPNs reflects the chronic inflammatory state intrinsic to these diseases, but specific numeric ranges are not standardized. Focus on trends over time and correlation with clinical symptoms, disease burden, and thrombotic risk rather than absolute values. 1