Procalcitonin: what your level actually means
Also known as: PCT · Updated 19 Aug 2026 · Educational — not medical advice
The short answer: Procalcitonin is normally very low, generally under about 0.1 ng/mL, and it rises specifically in response to significant bacterial infection more than it does with viral illness, which makes it useful for distinguishing the two in situations like pneumonia or suspected sepsis. Levels above roughly 0.5 ng/mL raise concern for a serious bacterial infection, and the higher it climbs, the greater the associated risk of severe sepsis, so this test is used mainly in hospital settings to help guide antibiotic decisions.
Where does your value sit?
This Procalcitonin value is inside the normal range. Your lab's printed reference range takes precedence — ranges vary slightly between laboratories.
What Procalcitonin tells you
Procalcitonin is a precursor protein that the body releases into the blood specifically in response to bacterial toxins and the inflammatory signals they trigger, rising much less with viral infections. This relative selectivity makes it a useful tool for hospitals trying to judge how likely a bacterial cause is and whether antibiotics are warranted, and for tracking how a serious infection is responding to treatment. (Illustration is schematic.)
Common reasons it rises
- Bacterial infection — the primary driver, with higher levels generally correlating with more severe or widespread infection.
- Sepsis or septic shock — a systemic bacterial infection that produces some of the highest procalcitonin levels seen clinically.
- Major surgery or severe trauma — can cause a temporary rise even without infection, due to the body's inflammatory response to tissue injury.
- Certain non-infectious critical illnesses — severe burns or prolonged shock from any cause can modestly raise it.
And reasons it runs low
- Viral infections — typically cause little to no rise in procalcitonin, which is part of why it helps distinguish bacterial from viral illness.
- No significant bacterial infection — a low result in someone with infection symptoms makes a bacterial cause less likely and can support holding off on antibiotics.
Does food or exercise change this?
Check with your doctor first: This test is used in hospital or emergency settings for serious infection; anyone with a high procalcitonin needs prompt medical evaluation rather than home management.
General guidance for adults — not a personal diet plan. Your doctor or dietitian knows your full picture.
Checked against: CDC: Sepsis · NHS: Sepsis · MedlinePlus: Sepsis
What to do next
Ask your doctor: “Does this procalcitonin level support starting or stopping antibiotics in my situation?”
Ask your doctor: “How does this result fit with my other infection markers, like white cell count or CRP?”
Ask your doctor: “If this is being monitored serially, what trend would indicate I'm improving?”
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Questions people ask
Why is procalcitonin better than CRP at detecting bacterial infection?
Procalcitonin tends to rise more specifically with bacterial infections and stays lower with viral illness, while CRP rises with almost any kind of inflammation regardless of cause. This relative specificity is why hospitals sometimes use procalcitonin to help decide whether antibiotics are truly needed.
Can procalcitonin be used to decide when to stop antibiotics?
Yes, in many hospital settings, a falling procalcitonin trend over serial measurements is used alongside clinical improvement to help guide how long antibiotics should continue. It's typically one input among several, rather than the sole basis for that decision. This approach has been studied specifically as a way to reduce unnecessary antibiotic exposure without compromising safety in appropriately selected patients.
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