Lyme Disease and Inflammatory Markers
Lyme disease can cause elevated CRP and ESR, but this elevation is most pronounced in early localized and early disseminated stages of infection, while later manifestations typically show normal or minimally elevated inflammatory markers.
Pattern of Inflammatory Marker Elevation by Disease Stage
Early Lyme Disease (Erythema Migrans and Early Dissemination)
- CRP and SAA levels are significantly elevated during early localized and early disseminated Lyme disease, when spirochete burden is highest in skin and blood 1
- In a study of patients with erythema migrans, 86% demonstrated abnormally elevated serum CRP concentrations (range 14-158 mg/L) 2
- Multiple proteins involved in acute immune responses, including CRP, show significantly altered serum levels at the time of initial diagnosis in patients presenting with erythema migrans 3
Late Lyme Disease
- CRP and SAA levels are NOT significantly elevated in later stages of active infection, after the organism has disseminated to extracutaneous sites 1
- This decline in inflammatory markers occurs despite ongoing active infection, reflecting a shift in the pathophysiology of disease 1
Special Circumstances
- Antibiotic-refractory Lyme arthritis shows elevated CRP (but not SAA), suggesting inflammatory mechanisms distinct from active infection 1
- Post-treatment Lyme disease syndrome also demonstrates elevated CRP levels driven by different inflammatory pathways than acute infection 1
Clinical Interpretation and Diagnostic Utility
Diagnostic Limitations
- Patients with single erythema migrans lesions typically lack Borrelia-specific IgG, making serologic diagnosis challenging in the earliest presentations 4
- The absence of elevated inflammatory markers does NOT rule out Lyme disease, particularly in later stages 1
Monitoring Treatment Response
- CRP can be useful for monitoring treatment response, as demonstrated by one patient whose CRP decreased from 29 mg/L to 13 mg/L after antibiotic therapy 2
- CRP is more useful than ESR for monitoring acute inflammatory conditions due to its shorter half-life and faster normalization with treatment 5
- ESR has a longer half-life than CRP, making it less responsive to acute changes in inflammation 5
Common Pitfalls to Avoid
- Do not rely on normal CRP/ESR to exclude Lyme disease, especially in patients presenting with late manifestations such as arthritis or neurological symptoms 1
- Be aware that many factors can cause falsely elevated or lowered inflammatory markers independent of infection 5
- Recognize that the timing of presentation significantly affects the likelihood of finding elevated inflammatory markers—early disease is more likely to show elevation than late disease 1