Procalcitonin is a precursor of the hormone calcitonin, normally produced in small amounts.

During systemic bacterial infections and sepsis, procalcitonin levels rise significantly.

Clinical uses include:

Detecting severe bacterial infections.

Differentiating bacterial vs viral infections.

Monitoring sepsis severity and progression.

Guiding antibiotic therapy (initiation, duration, discontinuation).

The test is performed using a blood sample.

Analyte: Procalcitonin concentration in blood serum.

Normal Range: < 0.1 ng/mL (varies slightly by lab).

Elevated Levels:

0.1–0.5 ng/mL: Possible local bacterial infection.

> 0.5 ng/mL: Suggests systemic bacterial infection or sepsis.

> 2 ng/mL: Strongly indicates severe sepsis or septic shock.

Clinical Use:

Differentiates bacterial vs viral infections.

Monitors infection severity and treatment response.

Helps reduce unnecessary antibiotic use.