PCT significantly increases during severe sepsis and septic shock, making it a valuable marker for determining prognosis and monitoring antibiotic therapy. PCT concentrations increase considerably in patients with septic shock and decrease with successful treatment of septic infection.
As the PCT increases, so does the risk for severe sepsis and septic shock. In healthy individuals, PCT is < 0.05 ng/mL. Moderately elevated levels (up to 2.0 ng/mL) indicate that sepsis is possible, and there is a slight risk of progression to severe sepsis. PCT levels in sepsis are generally greater than 2 ng/mL and often can reach values between 10 and 100 ng/mL in severe sepsis, or considerably higher in septic shock.
However, the role of PCT in the discrimination between SIRS and sepsis is still controversial. Although the majority of studies have shown higher values in patients with sepsis, a recent randomized trial did not support its use and patients in the PCT group actually had longer hospital stays.*
Reference: Faix J. Sepsis: New approaches to diagnosis and treatment. Clin Lab News. July 2012:38(7);12-14.