What is the use of Procalcitonin (PCT)?

From the Guidelines

Procalcitonin (PCT) is used as a biomarker to guide antibiotic therapy and diagnose bacterial infections, particularly sepsis [ 1 ]. It helps clinicians determine whether a patient has a bacterial infection, and if so, whether antibiotics are necessary and for how long they should be administered. Elevated procalcitonin levels indicate a potential bacterial infection, while decreasing levels suggest a positive response to treatment [ 1 ]. The use of procalcitonin can help reduce unnecessary antibiotic use, minimize antibiotic resistance, and improve patient outcomes [ 1 ].

Key Points

• Typical cutoff values for procalcitonin include 0.25-0.5 ng/mL for guiding antibiotic initiation and 0.25 ng/mL for guiding antibiotic discontinuation [ 1 ].
• PCT levels can be used to support shortening the duration of antimicrobial therapy in sepsis patients [ 1 ].
• PCT 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 ].
• 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 ].
• Decisions on initiating, altering, or discontinuing antimicrobial therapy should not be made solely based on changes in PCT or CRP levels [ 1 ].

Clinical Use

The clinical use of procalcitonin is supported by several studies, including a meta-analysis of 11 RCTs involving 4,482 patients, which reported that PCT-guided antibiotic treatment in ICU patients with infection and sepsis patients resulted in improved survival and lower antibiotic treatment duration [ 1 ]. Additionally, a systematic review and meta-analysis of 16 studies and greater than 5000 patients showed that PCT-guided antibiotic discontinuation appeared to decrease antibiotic utilization by 1 day and improve mortality [ 1 ]. However, the evidence is not strong, and the use of procalcitonin should be considered in the context of clinical judgment and other diagnostic tools [ 1 ].

From the Research

Use of Procalcitonin (PCT)

• Procalcitonin (PCT) is a host-response biomarker used to assess the likelihood of bacterial infections and guide antibiotic treatment 2, 3.
• PCT can help differentiate bacterial from non-bacterial infections and inflammation states, particularly in respiratory illness 2.
• The use of PCT has been shown to reduce antibiotic exposure and associated side-effects among patients with respiratory infection and sepsis 2, 3.

Clinical Applications of PCT

• PCT can be used to guide antibiotic stewardship, reducing the overuse of antibiotic therapy without increasing risk to patients 3, 4.
• PCT-guided antibiotic therapy has been shown to reduce the duration of antibiotic courses by 25-65% in hospitalized patients with community-acquired pneumonia and sepsis 3.
• PCT can be used to track the resolution of infection and guide decisions regarding early termination of antibiotic treatment 2.

Interpretation of PCT Levels

• Interpretation of PCT levels must always comprise the clinical setting and knowledge about assay characteristics 3.
• Highly sensitive PCT assays should be used in clinical practice, and cut-off ranges must be adapted to the disease and setting 3, 4.
• PCT levels should be used in combination with clinical and radiological findings, evaluation of severity of illness, and patient characteristics to correctly interpret results 4.

Limitations and Future Directions

• There are uncertainties on the optimal cut-offs to be used for starting or discontinuing antibiotic treatment in patients with suspected bacterial infection or sepsis 5.
• Several diseases can produce an elevation of PCT levels, resulting in false positive results 5.
• Further research is needed to fully understand the role of PCT in different clinical settings and to establish standardized guidelines for its use 6, 5.