PCT >2.0 ng/mL:

A PCT level above 2.0 mg/mL on the first day of ICU admission is associated with a high risk for progression to severe sepsis and/or septic shock

PCT <0.5 ng/mL:

A PCT level below 0.5 ng/mL on the first day of ICU admissioin is associated with a low risk for progression to severe sepsis and/or septic shock.

Note:

PCT levels <0.5 ng/mL do not exclude an infection, because localized infections may also be associated with such low levels.  If the PCT measurement is done very early after the systemic infection process has started, these values may still be low.

Various non-infectious conditions are known to induce changes in PCT levels, therefore PCT levels between 0.5-2.0 ng/mL should be interpreted in the context of the specific clinical background and condition(s) of the individual patient.  It is recommended to retest PCT within 6-24 hours if any concentrations are ≤ 2.0 ng/ml are obtained.