27/02/2026
A Procalcitonin test measures the level of procalcitonin in the blood to help diagnose and assess severe bacterial infections, especially sepsis. Normally, procalcitonin levels are very low, but they rise significantly in response to a systemic bacterial infection, making it a useful biomarker for distinguishing between bacterial and viral infections and guiding treatment, such as deciding when to start or stop antibiotics.
Purpose of the test
Diagnosing sepsis: To help diagnose a serious bacterial infection that can lead to sepsis, a life-threatening condition.
Distinguishing infection type: To help determine if an infection is bacterial or viral, as procalcitonin levels rise more dramatically in bacterial infections.
Assessing severity: To help assess the severity of a bacterial infection and the risk of progression to more severe outcomes like septic shock.
Guiding treatment: To help physicians decide on the appropriate use of antibiotics, monitor how a patient is responding to treatment, and determine when to stop antibiotic therapy.
Monitoring other conditions: In some cases, elevated levels can also indicate other conditions, such as certain tumors, meningitis, or organ rejection after a transplant.
How the test works
A blood sample is taken from a vein, typically in your arm.
The sample is sent to a lab for analysis to measure the procalcitonin level.
The results help doctors understand the likelihood and severity of a bacterial infection.
What high levels mean
High levels: A high procalcitonin level is a strong indicator of a serious bacterial infection or sepsis. The higher the level, the more severe the infection may be.
Normal levels: Very low or normal levels of procalcitonin are found in healthy individuals and in cases of non-bacterial inflammation. .