Reference Range

Interpretive Guidelines: Procalcitonin

Interpretation of Levels in ng/mL

<0.5 ng/mL:  Systemic infection is not likely, and progress of systemic infection is low risk.

0.5-2.0 ng/mL:  Levels in this range are a nonspecific indicator of inflammation and can be seen in conditions such as autoimmune disease and localized infection.  Early onset sepsis may be in this range.  Condsider repet testing in 6-12 hours if appropriate.

2.0-10.0 ng/mL:  Systemic infection is likely (unless other cause of inflammation is known), and progression to severe systemic infection is high risk.

>10 ng/mL:  Major Systemic inflammatory response, almost always due to severe bacterial sepsis.

MONITORING OF ANTIBIOTIC THERAPY:
Antibiotic therapy can be stopped if one of the following sets of criteria is met:

1.  Clinical signs and symptoms of infection are improved + follow-up PCT is less than 0.5 ng/mL.
2.  Clinical signs and symptoms of infection are improved + follow-up PCT drop to 25 to 35% of the initial value over 3 days or more.