From the Guidelines
This pattern of lab results—normal C-reactive protein (CRP), elevated erythrocyte sedimentation rate (ESR), and very high interleukin levels—suggests an inflammatory process that may not necessitate immediate escalation of immunosuppressive therapy, but rather warrants clinical observation and monitoring, as indicated by the 2021 American College of Rheumatology/Vasculitis Foundation guideline for the management of giant cell arteritis and takayasu arteritis 1.
Key Considerations
- The discrepancy between CRP and ESR levels is noteworthy, as they typically rise together in most inflammatory conditions.
- High interleukin levels, particularly IL-6, can drive ESR elevation without corresponding CRP increases in some cases, as seen in certain autoimmune conditions involving IL-6 pathways.
- The presence of elevated ESR and normal CRP in the context of high interleukin levels may indicate a specific cytokine-driven inflammatory process, which could be associated with conditions like rheumatoid arthritis, systemic lupus erythematosus, or adult-onset Still's disease.
Clinical Approach
- Consultation with a rheumatologist is recommended for proper evaluation and interpretation of these lab results, as this pattern often requires specialized testing.
- While awaiting specialist consultation, tracking symptoms such as joint pain, skin rashes, fever patterns, and fatigue would be helpful for diagnosis.
- It is advisable to avoid taking anti-inflammatory medications before testing if possible, as they may mask important diagnostic findings.
- Treatment will depend on the specific diagnosis but might include targeted biologic therapies that block specific interleukin pathways, such as tocilizumab for IL-6 mediated conditions, as suggested by the guideline for managing conditions with similar inflammatory markers 1.
From the Research
Significance of Normal CRP Levels, Elevated ESR, and Markedly Increased IL Levels
- Normal C-Reactive Protein (CRP) levels and elevated Erythrocyte Sedimentation Rate (ESR) can indicate the presence of chronic inflammatory conditions, as ESR is more helpful in monitoring these conditions due to the longer half-life of fibrinogen 2.
- Markedly increased Interleukin (IL) levels, in combination with normal CRP and elevated ESR, may suggest an underlying inflammatory or autoimmune condition, such as systemic lupus erythematosus (SLE) 3.
- The combination of normal CRP, elevated ESR, and increased IL levels can be seen in patients with new onset rheumatic disease, such as polymyalgia rheumatica or seronegative rheumatoid arthritis 4.
- It is essential to consider the clinical context and other laboratory results when interpreting these markers, as discrepancies between ESR and CRP measurements can occur due to various physiological factors, including noninfectious conditions and resolution of inflammation 5, 6.
- In patients with SLE, acute-phase proteins behave differently depending on the kind of organ damage evaluated, with serum complement proteins being reliable laboratory markers for nephritis, while CRP is best in patients with arthritis 3.