How to Use: C-reactive Protein

C-reactive protein (CRP) is an acute-phase protein that increases 4-6 h after an inflammatory trigger and peaks at 36-50 h. Levels decrease rapidly with the resolution of inflammation. CRP is generally highly elevated in invasive bacterial infections and is often used as a marker of inflammation. A single CRP level is neither sensitive nor specific enough to identify all children with serious bacterial infection. However, a raised CRP does suggest serious bacterial infection and should suggest further assessment is needed. CRP levels that fail to decrease, or continue to rise, after 48 h of antibiotic therapy suggest treatment failure. In infants with suspected neonatal sepsis, two CRP measurements 24 h apart that are <10 mg/l are useful in excluding sepsis.