From the Guidelines
Procalcitonin should be measured in addition to bedside clinical evaluation in critically ill patients with a new fever and no clear focus of infection, but only when the probability of bacterial infection is deemed low to intermediate, as suggested by the most recent guidelines from the Society of Critical Care Medicine and the Infectious Diseases Society of America 1.
Key Points to Consider
- Procalcitonin (PCT) is a biomarker that helps diagnose bacterial infections and guide antibiotic therapy decisions, with levels rising in proportion to infection severity 1.
- Normal PCT 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 strongly indicate severe bacterial infection or sepsis 1.
- PCT is particularly valuable because it increases specifically in response to bacterial infections but remains relatively low in viral infections, helping clinicians distinguish between these conditions and make informed decisions about antibiotic use 1.
- The test is most useful in respiratory infections, sepsis evaluation, and monitoring infection response, though it should always be interpreted alongside clinical assessment and other diagnostic tests rather than used in isolation 1.
- Recent studies, including a meta-analysis of 11 RCTs involving 4,482 patients, have shown that PCT-guided antibiotic treatment in ICU patients with infection and sepsis patients resulted in improved survival and lower antibiotic treatment duration 1.
Clinical Application
- Measuring PCT or CRP in critically ill patients with a new fever and no clear focus of infection with low to intermediate clinical probability of bacterial infection is recommended in addition to bedside clinical evaluation 1.
- However, in patients with high clinical probability of bacterial infection, measuring PCT is not recommended to rule out bacterial infection 1.
- PCT levels of less than 0.5 µg/L or levels that decrease by greater than or equal to 80% from peak levels may guide antibiotic discontinuation once patients stabilize 1.
- Clinicians should not initially withhold antibiotics in ICU patients with suspected sepsis, but PCT can help guide antibiotic discontinuation once patients stabilize 1.
From the Research
Procalcitonin Overview
- Procalcitonin (PCT) is a host-response biomarker that has shown clinical value for assessing the likelihood of bacterial infections and guiding antibiotic treatment 2, 3.
- PCT levels rise in response to systemic inflammation, especially of bacterial origin, and can be used to differentiate bacterial from non-bacterial infections and inflammation states 2, 4.
Clinical Applications
- PCT-based algorithms can safely reduce antibiotic use in clinical scenarios such as respiratory infections and suspected sepsis 2, 5.
- In stable, low-risk patients with respiratory infections, PCT levels of <0.25 µg/L can guide the decision to withhold antibiotics or stop therapy early 2.
- In critically ill patients with suspected sepsis, PCT levels of <0.5 µg/L or levels that decrease by ≥80% from peak can guide discontinuation of antibiotics once patients stabilize 2.
Diagnostic and Therapeutic Guidance
- PCT can help diagnose sepsis and guide antibiotic therapy, but its use should be combined with careful patient assessment, evidence-based clinical algorithms, and continuous notification and regular feedback from all antibiotic stewardship stakeholders 3, 5.
- Low PCT levels can help rule out bacterial infection in patients with low pretest probability for bacterial infection and low-risk general condition, while high-risk individuals and/or high pretest probability for infection require empiric antibiotic treatment 3.
- PCT monitoring can track the resolution of infection and guide decisions regarding early termination of antibiotic treatment 3, 6.
Pediatric Intensive Care
- PCT is frequently used in pediatric intensive care units to guide therapeutic decisions in children with suspected bacterial infections and sepsis 6.
- Interpretation of PCT in critically ill children can be challenging due to the complexity of underlying conditions and its impact on PCT values, and requires consideration of the clinical context, timing of measurement, and evidence on PCT values 6.