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.

Reference Ranges

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
Each laboratory should check if the reference ranges are transferable to its own patient population and determine own reference ranges if necessary. For diagnostic purposes, the results should always be assessed with the patient’s medical history, clinical examinations and other findings.

*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. 


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