Procalcitonin (PCT), the precursor of the hormone calcitonin, is primarily expressed in thyroid C cells and PCT serum levels in healthy individuals are very low (< 0.05 ng/mL). In response to microbial systemic infections and sepsis, PCT is ubiquitously expressed in multiple tissues via stimulation by inflammatory cytokines or bacterial endotoxins and may increase up to 1000 ng/mL.
|Systemic infection (sepsis) is unlikely*||< 0.5 ng/mL|
|Systemic infection (sepsis) is possible. Patient should be closely monitored||≥ 0.5 and < 2 ng/mL|
|Represent a high risk of severe sepsis and/or septic shock||≥ 2 and < 10 ng/mL|
|Severe sepsis or septic shock, almost exclusively due to severe bacterial infection||≥ 10 ng/mL|
*Low levels do not exclude an infection, because localized infections (without systemic signs) may be associated with such low levels.
Note: PCT levels may be elevated independently of bacterial infection in neonates (< first 3 days of life, physiological elevation). Increased levels of PCT may also occur in patients with special medical conditions eg. polytrauma, major surgery and severe burns.