What is Procalcitonin (PCT)?

PCT is a marker of inflammatory response and is stimulated by bacterial products (endotoxins/LPS) and cytokines (IL-1,IL-2, IL-6, TNFα).1–5 The exact biological role of PCT remains largely unknown, however, recent data suggests that PCT may play a pathologic role in sepsis.2


PCT is 116 amino acid prohormone of the hormone calcitonin. Calcitonin is exclusively produced by C-cells of the thyroid gland in response to hormonal stimuli, whereas PCT can be produced by several other cell types from a wide range of organs in response to inflammation or infection.1,2,6

PCT and Sepsis
Plasma PCT has a half life of 25–30 hours.1 Levels typically increase within 3–6 hours of the stimulus,2,4 and higher levels are associated with poorer prognosis.7 Elevated values are highly suggestive of an infection, typically bacterial, with a systemic response (sepsis, or severe sepsis or septic shock). In healthy people, PCT concentrations are typically below 0.05 ng/mL, but concentrations can increase up to 1000 ng/mL in patients with sepsis, severe sepsis or septic shock.1,3 Average levels of PCT increase from SIRS to septic shock, with the highest levels associated with severe sepsis and septic shock. 7


PCT has been shown to be a useful tool that can aid in the diagnosis of sepsis.2,4,7 PCT levels can be helpful in facilitating early diagnosis thus allowing for early therapeutic interventions that have been shown to improve patient outcomes.8

PCT (ng/mL)

Possible causes


Normal values

Local inflammation or infection is possible, systemic inflammatory response unlikely

On first day of ICU admission indicates a low risk for progression to severe sepsis and/or septic shock

≥0.5 and <2.0

Systemic inflammatory response present due to infection, or severe trauma, or major surgery or cardiogenic shock

If the patient has a proven infection it could be sepsis

≥2.0 and <10

Likely to be sepsis (severe systemic inflammatory response due to infection)

On first day of ICU admission indicates a high risk for progression to severe sepsis and/or septic shock


Severe sepsis or septic shock

Organ dysfunction

High risk of death

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