A blood test used to differentiate bacterial infection and sepsis. It is more specific to bacterial infections than CRP and helps guide antibiotic therapy.
Indication
- Evaluation of suspected sepsis (widespread bacterial infection)
- Differentiation between bacterial and viral causes in respiratory tract infections
- Infection monitoring in intensive care patients
- Decision-making for starting and stopping antibiotic therapy
- Suspected post-surgical infection
- Investigation of the cause of fever
- Infection surveillance in immunocompromised patients
Preparation
- No special preparation is required
- It is generally requested in hospitalized patients or those presenting to the emergency department
- It is evaluated together with other concurrent infection markers (CRP, white blood cells)
How it's performed
- A venous blood sample is drawn from the arm under sterile conditions
- The sample is promptly sent to the laboratory
- Procalcitonin levels are measured by an immunological method (ECLIA / CLIA)
- Results are usually available within 1-2 hours
- It can be repeated every 24-48 hours during treatment monitoring
Post-procedure
- Below 0.25 ng/mL: low; bacterial infection is unlikely
- 0.5 ng/mL and above: increases the likelihood of bacterial infection
- Above 2 ng/mL: suggests severe sepsis
- If treatment is effective, levels drop rapidly; monitoring guides treatment duration
- Results are interpreted alongside clinical findings and other tests
Risks
- Local bruising or pain after blood draw
- Very rare risk of infection
- Mild elevation may occur in conditions such as post-surgery, trauma, or burns even without infection
- It cannot establish a diagnosis on its own; clinical evaluation is essential
FAQ
What is the difference between procalcitonin and CRP?
Procalcitonin is more specific to bacterial infections than CRP; it usually does not rise in viral infections and provides more accurate guidance for antibiotic decisions.
Does high procalcitonin always mean infection?
No. It may also rise mildly in surgery, trauma, burns, and some tumors; however, high values raise strong suspicion of bacterial infection and sepsis.
How is it used in antibiotic decisions?
Low values may help avoid unnecessary antibiotic use; high values support early initiation of antibiotics. The decision always rests with the physician.
How long does it take to get results?
In modern laboratories, results can be reported within 1-2 hours; rapid results are important in emergency department and intensive care monitoring.
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