Procalcitonin for early diagnosis and differentiation of SIRS, sepsis, severe sepsis, and septic shock

Objective: To determine the value of procalcitonin (PCT) in the early diagnosis (and differentiation) of patients with SIRS, sepsis, severe sepsis, and septic shock in comparison to C-reactive protein (CRP), white blood cell and thrombocyte count, and APACHE-II score (AP-II).¶Design: Prospective cohort study including all consecutive patients admitted to the ICU with the suspected diagnosis of infection over a 7-month period.¶Patients and methods: A total of 185 patients were included: 17 patients with SIRS, 61 with sepsis, 68 with severe sepsis, and 39 patients with septic shock. CRP, cell counts, AP-II and PCT were evaluated on the first day after onset of inflammatory symptoms.¶Results: PCT values were highest in patients with septic shock (12.89 ± 4.39 ng/ml; P < 0.05 vs patients with severe sepsis). Patients with severe sepsis had significantly higher PCT levels than patients with sepsis or SIRS (6.91 ± 3.87 ng/ml vs 0.53 ± 2.9 ng/ml; P < 0.001, and 0.41 ± 3.04 ng/ml; P < 0.001, respectively). AP-II scores did not differ significantly between sepsis, severe sepsis and SIRS (19.26 ± 1.62, 16.09 ± 2.06, and 17.42 ± 1.72 points, respectively), but was significantly higher in patients with septic shock (29.27 ± 1.35, P < 0.001 vs patients with severe sepsis). Neither CRP, cell counts, nor the degree of fever showed significant differences between sepsis and severe sepsis, whereas white blood cell count and platelet count differed significantly between severe sepsis and septic shock.¶Conclusions: In contrast to AP-II, PCT appears to be a useful early marker to discriminate between sepsis and severe sepsis.