Inflammation
Procalcitonin
Procalcitonin (PCT) is the peptide precursor of the hormone calcitonin, and its blood concentration rises quickly during systemic bacterial infection. At the point of care it is used mainly to support the recognition of sepsis and to help inform antibiotic decisions, always alongside the wider clinical picture.
Why it is measured
PCT climbs within a few hours of a serious bacterial insult and falls as infection resolves, so serial measurement can help distinguish bacterial sepsis from viral or non-infective causes. This dynamic behaviour underpins its role in antibiotic stewardship pathways.
| Typical range | Indicative adult values: apparently healthy individuals are typically below 0.1 ng/mL (numerically equal to µg/L). A commonly cited decision threshold for significant systemic bacterial infection sits around 0.5 ng/mL, with values above 2.0 ng/mL associated with greater severity. Cut-offs and reference intervals vary by assay method, population and clinical context. |
|---|---|
| Sample | Whole blood (capillary or venous), or plasma/serum depending on the platform. Several point-of-care systems accept a small whole-blood volume of roughly 20 to 100 µL. |
| Turnaround | Approximately 15 to 25 minutes on point-of-care immunoassay analysers. |
Point of care devices that report it
- Radiometer AQT90 FLEX immunoassay analyser
- BRAHMS PCT direct (Thermo Fisher Scientific)
- Wondfo Finecare FIA PCT (Suresign Finecare)
Questions, answered
Does a normal procalcitonin result rule out infection?
No. A low PCT lowers the likelihood of systemic bacterial infection but does not exclude it. Values can still be low if blood is sampled very early, often within about 6 hours of onset, before levels have risen, and PCT may stay low in localised infection. Results are interpreted together with the full clinical assessment, not in isolation.
What can raise procalcitonin without a bacterial infection being present?
PCT can rise in several non-infective situations, including major surgery, severe trauma, burns, cardiogenic shock and certain forms of severe physiological stress, and it is normally higher in the first days of life. This is general educational background and not an interpretation of any individual result.
How is point-of-care procalcitonin used in relation to antibiotics?
In some clinical pathways, PCT levels and their trend over time are used to support antibiotic stewardship, for example to help indicate whether antibacterial therapy is likely to be of benefit and when it might be reviewed or stopped. Such decisions remain clinical and follow local protocols and guidelines.