What are the indicative CRP (C-Reactive Protein) and ESR (Erythrocyte Sedimentation Rate) values for osteomyelitis?

From the Guidelines

In osteomyelitis, CRP values are typically elevated above 10-20 mg/L, often reaching 50-100 mg/L or higher in acute cases, while ESR is usually elevated above 30 mm/hr and frequently exceeds 70-100 mm/hr, with a highly elevated ESR (≥70 mm/h) having a sensitivity, specificity, and AUC for the diagnosis of DFO of 81%, 80%, and 0.84, respectively, as reported in the most recent study 1.

Key Points

• CRP and ESR are valuable indicators of infection severity and treatment response in osteomyelitis, although they are not specific to the condition.
• CRP rises rapidly within 6-8 hours of infection onset and normalizes faster, typically within days of effective treatment, making it useful for monitoring treatment efficacy 1.
• ESR increases more slowly and may remain elevated for weeks despite clinical improvement.
• The degree of elevation of these markers often correlates with infection severity, but values can vary based on the causative organism, infection chronicity, patient age, and comorbidities.
• A highly elevated ESR (≥70 mm/h) is suggestive of osteomyelitis, with a sensitivity of 81%, specificity of 80%, and AUC of 0.84 for the diagnosis of DFO 1.

Diagnostic Considerations

• Normal inflammatory markers do not exclude osteomyelitis, especially in chronic or partially treated cases.
• Diagnosis should incorporate clinical assessment, microbiological data, and imaging findings for comprehensive evaluation.
• These markers should be measured at diagnosis to establish a baseline and then monitored regularly during treatment, with declining values suggesting therapeutic success.

Treatment and Outcome

• Appropriate treatment of osteomyelitis can lead to resolution of signs and symptoms, but the outcome is often less favorable when infection involves deep soft tissue structures or bone, and may require surgical debridement, bone resection, or partial amputations 1.
• Factors that predict healing include the absence of exposed bone, palpable pedal pulses, and adequate blood pressure in the toe or ankle, among others 1.

From the Research

Indicative CRP and ESR Values for Osteomyelitis

The following values are indicative of osteomyelitis:

• ESR:

  • 60 mm/h is considered a high likelihood of osteomyelitis 2

  • 49 mm/h is considered indicative of osteomyelitis in diabetic foot cases 3

  • 20 mm/h is elevated and initially found in 92% of acute hematogenous osteomyelitis cases 4

• CRP:

  • 7.9 mg/dL is considered a high likelihood of osteomyelitis 2

  • 35 mg/L is considered indicative of osteomyelitis in diabetic foot cases 3

  • 19 mg/L is elevated and initially found in 98% of acute hematogenous osteomyelitis cases 4

  • 6 mg/L is considered elevated in cases of osteomyelitis 5

Variability in CRP and ESR Values

It's essential to note that CRP and ESR values can vary depending on the infecting organism and the specific case of osteomyelitis:

• Staphylococcus aureus and antibiotic-resistant organisms tend to have higher mean CRP and ESR values 6
• Culture-negative and non-pyogenic organisms tend to have lower laboratory values 6
• The effectiveness of therapy and recovery can be reflected in the decrease of CRP and ESR values 4