Extremely elevated C-reactive protein.

Background: C-reactive protein (CRP) is a widely used inflammatory marker. Yet, the clinical significance and outcome of extremely elevated CRP levels are poorly characterized.

Methods: We collected all patients seen at a university hospital in 2004 with at least one CRP level above 500 mg/l and retrospectively analyzed their electronic files, focusing on patient characteristics, clinical diagnosis, microbiology and vital outcome.

Results: CRP was above 500 mg/l in 130 patients with a median age of 62 years. Patient characteristics, settings, etiologies of inflammation, comorbidities and microbiology varied widely. Infections, mainly bacterial, accounted for 88% of episodes. Outcome was fatal in 36% of all patients and in 61% of patients with active malignancies.

Conclusion: A wide variety of infections, especially bacterial, that are generally readily identified account for the majority of instances of extreme CRP elevation. Mortality is high, certainly in oncological patients.