C-reactive protein as an indicator of infection relapse in patients with abdominal sepsis.

C-reactive protein (CRP) concentrations were monitored serially in 97 patients with abdominal sepsis to determine if differences in infection type or site would produce diagnostic or prognostic CRP level elevations. After surgery and abdominal infection, the average (+/- SD) CRP peak values were 21.2 +/- 9.0 mg/dL. The CRP values rose markedly with infection, rose further with surgery, and subsided to less than 10 mg/dL with cure. Persistent levels of more than 10 mg/dL indicated abscess formation or continued infection. The average normal value at complete tissue healing after resolution of infection was 1.2 mg/dL, which was not different from that for healthy volunteers. Analysis suggested that CRP concentrations were not predictive of the type, site, or severity of abdominal infection; however, since persistent elevations were frequently associated with new or unresolved bacterial infection, serial determinations may be helpful in monitoring the course of disease and response to treatment.