Procalcitonin

Procalcitonin is a protein your body makes as a precursor to the hormone calcitonin. During systemic bacterial infections, many tissues release procalcitonin into the bloodstream in higher amounts.

This blood test measures the level of procalcitonin to help identify bacterial infections and the body’s inflammatory response. It is often used alongside your symptoms, exam findings, and other tests to clarify what may be causing an illness.

Procalcitonin can help your care team judge the likelihood of a significant bacterial infection, such as sepsis or a severe pneumonia, and assess how active that infection may be. It is also used to monitor how you are responding to treatment over time.

Doctors may use procalcitonin results to support decisions about starting or stopping antibiotics, which helps avoid unnecessary antibiotic use and its side effects. The test is not a stand‑alone answer, but it can add confidence to clinical decisions when combined with cultures, imaging, and other labs.

Higher procalcitonin levels tend to be more consistent with bacterial infection, while lower levels suggest a nonbacterial cause or a more localized process. Your clinician will interpret your result in the context of your symptoms, exam, and other tests.

Trends over time are often more informative than a single value. Levels can rise with major surgery, severe trauma, burns, or in certain medical conditions like kidney disease, and early testing in an illness may still look low before increasing. Tell your care team about any supplements or high-dose biotin you take, since some assays can be affected. Based on your results, your clinician may recommend repeat testing, cultures, imaging, or treatment adjustments.