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Procalcitonin

Published: July 27, 2026Updated: August 25, 2026

Procalcitonin measures the level of a precursor protein of calcitonin, which increases in bacterial infections and can aid in diagnosing sepsis and other bacterial infections.

Quick summary

Procalcitonin is a biomarker for diagnosing bacterial infections and sepsis.

Medically reviewed by WellAlly Editorial TeamLast reviewed August 25, 2026Editorial policy

Key facts at a glance

Units
ng/mL
Clinical utility
diagnostic
Result kind
quantitative
FDA-cleared
Roche PCT, Abbott PCT, Brahms PCT, Thermo Fisher PCT
interpretation: {"text":"Levels between 0–0.25 ng/mL are considered normal and indicate a low likelihood of bacterial infection.","label":"Low Levels"}; {"text":"Levels above 0.5 ng/mL suggest a high probability of bacterial infection or sepsis, warranting further investigation and treatment.","label":"High Levels"}

Procalcitonin (PCT) is a peptide precursor of the hormone calcitonin, which is produced by the C cells of the thyroid gland. Its levels rise significantly in response to bacterial infections and sepsis, making it a valuable diagnostic tool.

In healthy individuals, procalcitonin levels are typically very low (0–0.25 ng/mL). However, in the presence of bacterial infections, levels can rise dramatically, often exceeding 0.5 ng/mL.

The utility of procalcitonin testing lies in its ability to help differentiate between bacterial and viral infections, guiding clinicians in making informed decisions about the use of antibiotics.

Frequently asked questions

What is a normal procalcitonin level?
A normal procalcitonin level is between 0–0.25 ng/mL.
How is procalcitonin used in clinical practice?
Procalcitonin is used to help diagnose bacterial infections and sepsis, and to guide decisions about antibiotic therapy.
  1. 1
    Procalcitonin - Lab Tests OnlineSource
  2. 2
    Clinical Utility of Procalcitonin - NCBISource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 25, 2026. · Read our editorial policy