Abstract
Procalcitonin (PCT) is formed in IL6-mediated, IL8-mediated, and TNFα-mediated systemic inflammation conditions, in multiple organs and structures of the body. In patients with sepsis, significantly increased PCT levels are found. The PCT levels are highly correlated with the severity of the illness, and decreased PCT levels under therapy correlates with a better prognosis. In the differential diagnosis, measuring the PCT level helps differentiate between bacterial and viral infections. Noninfectious inflammatory reactions can, however, show moderately increased PCT levels. Cut-off values depend on renal and hepatic function. A therapeutic algorithm using PCT levels could be used for determining duration of a course of antibiotics, which can reduce antibiotic usage. In this paper, the differential diagnostic and differential therapeutic possibilities of PCT levels for critically ill patients are discussed.