Procalcitonin (PCT)
Blood marker that can rise sharply in serious bacterial infections and sepsis
Also known as
Definition
Procalcitonin (PCT) is present only in very small amounts in the blood of healthy people. During a serious bacterial infection, cells in many parts of the body release PCT into the blood. The test is used mainly in hospital for very ill people, to tell a bacterial from a viral infection, to estimate the risk of sepsis and to follow the course of treatment. It is not meant for routine checks in healthy people.
| Parameter | Value |
|---|---|
| Unit | ng/ml (µg/l) |
| Reference Range | Very low in healthy people. The lab sets cut-offs and how they are graded; the range printed on your report is what counts, and your doctor interprets the result. |
Agree on your personal target range with your doctor.
1 ng/ml equals 1 µg/l.
↓ What a low value means
A low PCT level is normal in healthy people. When a bacterial infection is being treated, a falling or low level can, according to MedlinePlus, indicate that treatment is working. The test does not show which germ is causing an infection, and a single value does not replace your doctor's overall assessment of symptoms, examination and other findings.
↑ What a high value means
According to MedlinePlus, the higher the PCT level, the higher the risk of sepsis and septic shock. Clearly raised levels can be related to sepsis or a serious bacterial infection affecting the whole body. Moderately raised levels also occur in early stages of such an infection, and after injuries, severe burns, surgery or a severe heart attack. Slightly raised levels can be related to a localized bacterial infection, such as a urinary tract infection, or to a viral infection. Interpreting the result is a job for your doctor.
When to test
The test is usually ordered when there are signs of sepsis or a serious bacterial infection, such as fever or chills, clammy skin, confusion, severe pain, a racing heart, shortness of breath, low blood pressure or little urine. No preparation is needed. Sepsis is a medical emergency: if an infection is not improving or is getting worse, get medical help right away.
Frequently asked questions
What is the difference between procalcitonin and CRP? +
CRP is made by the liver in response to inflammation and, according to MedlinePlus, rises with bacterial and viral infections as well as with autoimmune and other inflammatory conditions. Procalcitonin is measured mainly in very ill people, to tell a bacterial from a viral infection and to estimate the risk of sepsis. Which test makes sense is for your doctor to decide.
Does the test show which bacteria are causing the infection? +
No. Procalcitonin does not show which germ is involved. Other tests are needed for that.
Can procalcitonin be raised without an infection? +
Yes. According to MedlinePlus, tissue damage from injuries, severe burns, recent surgery or a severe heart attack can also raise the level moderately.
Is procalcitonin part of a routine check-up? +
Usually not. The test is used mainly for very ill people in hospital when a serious infection is suspected.
Procalcitonin (PCT)
Sources
Last updated: October 05, 2026
This information is for orientation only and does not replace medical advice. Reference ranges can vary by laboratory, method and country.