Procalcitonin is a good marker for the diagnosis of infection and the severity of illness in patients with SIRS

To understand the presence or absence of bacterial infection in patients with systemic inflammatory response syndrome (SIRS), the level of procalcitonin (PCT), a precursor of calcitonin, was determined. Subjects consisted of 14 SIRS patients without complication by bacterial infection, 14 SIRS patients complicated by sepsis, and 14 SIRS patients complicated by severe sepsis and septic shock. PCT levels in SIRS patients with sepsis (2.9 ± 2.3 ng/ml) were significantly higher than those in SIRS patients without complication by infection (0.7 ± 1.1 ng/ml). However, there were no significant differences in the levels of C-reactive protein (CRP), interleukin 6 (IL-6) or tumor necrosis factor-α (TNF-α) between the two groups. PCT levels in SIRS patients with severe sepsis and septic shock (172.2 ± 276.3 ng/ml) were significantly higher than those in SIRS patients with sepsis. Levels of CRP, IL-6 and TNF-α were also significantly higher in the patients with sepsis compared to those in patients with local infection. Significant correlations were observed between the levels of PCT and those of CRP, IL-6 and TNF-α in SIRS patients. It was suggested that to measure the levels of procalcitonin in patients with SIRS is useful to diagnose the infection and severity of illness.