Figure 1

Example 1 (left): sepsis secondary to hydronephrosis. This graph clearly shows the rise in procalcitonin (PCT) during early onset of sepsis and its fall during antibiotic treatment. Antibiotics were discontinued when the PCT level fell to 80% of its peak value on day 8. Example 2 (right): laparoscopic cholecystectomy complicated by bile peritonitis. Good response to antibiotics initially, but PCT started to rise on day 12 which prompted us to change antibiotics. Serial PCT is useful to assess the response to treatment.