From the Guidelines
Procalcitonin (PCT) is the most recommended biomarker to help diagnose and monitor bacterial infections, particularly sepsis, as it has been shown to have a high diagnostic accuracy and can guide antibiotic therapy decisions. This blood test measures levels of procalcitonin, a protein that increases significantly during bacterial infections but remains relatively low during viral infections or non-infectious inflammatory conditions. Normal procalcitonin levels are typically below 0.05 ng/mL, while levels above 0.5 ng/mL suggest possible bacterial infection, and levels exceeding 2.0 ng/mL are strongly associated with sepsis 1.
Key Points
- Procalcitonin testing is valuable for guiding antibiotic therapy decisions, as rising levels may indicate worsening infection requiring aggressive treatment, while declining levels suggest effective therapy.
- The test can be repeated every 24-48 hours to monitor treatment response.
- Procalcitonin works as a biomarker because bacterial endotoxins trigger its production by various body tissues during infection, whereas viral infections stimulate interferon production which inhibits procalcitonin release.
- While useful, procalcitonin should be interpreted alongside clinical assessment and other laboratory findings for optimal diagnostic accuracy.
Comparison with Other Biomarkers
- C-reactive protein (CRP) is another biomarker that can be used to diagnose and monitor bacterial infections, but its diagnostic accuracy is lower than that of procalcitonin 1.
- Other biomarkers, such as endotoxin activity assay, have been investigated but are not as widely used or recommended as procalcitonin 1.
Clinical Application
- Procalcitonin levels can be used to support the discontinuation of empiric antibiotics in patients who initially appeared to have sepsis, but subsequently have limited clinical evidence of infection 1.
- Procalcitonin-guided antibiotic treatment has been shown to improve survival and reduce antibiotic treatment duration in ICU patients with infection and sepsis 1.
From the Research
Biomarker for Diagnosing and Monitoring Bacterial Infections
- Procalcitonin (PCT) is a biomarker that helps diagnose and monitor bacterial infections, particularly sepsis 2, 3, 4, 5, 6
Characteristics of Procalcitonin
- PCT is a host-response biomarker that assesses the likelihood of bacterial infections and guides antibiotic treatment 3
- PCT levels mirror the severity of illness and outcome 4
- PCT is widely used with other biomarkers, such as white blood cells (WBC) count and C reactive protein (CRP), to guide antibiotic therapy 4
Diagnostic and Prognostic Power of Procalcitonin
- PCT has superior diagnostic accuracy for sepsis compared to traditional biomarkers 2
- PCT alone or combined with WBC shows the best diagnostic and prognostic power 4
- PCT is a helpful biomarker for early diagnosis of sepsis in critically ill patients 5
Clinical Usefulness of Procalcitonin
- PCT-guided algorithm reduces length of antibiotic treatment in surgical intensive care patients with severe sepsis 6
- PCT guidance leads to a significant reduction of antibiotic treatment without adverse effects on outcome 6
- Monitoring of PCT is a helpful tool for guiding antibiotic treatment in surgical intensive care patients with severe sepsis 6