Procalcitonin

<0.5 ng/ml: PCT level below 0.5 ng/ml does not exclude an infection. Localized infections may be associated with these low levels. Also, if the PCT measurement is done at an early stage of a bacterial infection (<6 hours), PCT value may still be low.
0.5 - <2.0 ng/ml: It has a moderate risk for progression to a severe systemic infection. The patient should be closely monitored clinically and re-assessed for PCT levels within 6-24 hours.
2.0 - <10 ng/ml: It has a high risk for progression to a severe systemic infection or sepsis.
=,>10 ng/ml: It has a high likelihood of severe sepsis or septic shock. It may has high risk of death.