Is procalcitonin (PCT) useful for assessing post-splenectomy sepsis?

From the Guidelines

Procalcitonin is useful for post-splenectomy infection assessment, though it should not be used as the sole diagnostic marker. In post-splenectomy patients, who are at increased risk for overwhelming post-splenectomy infection (OPSI), procalcitonin can serve as an early biomarker of bacterial infection, typically rising within 2-4 hours of infection onset 1. When evaluating potential infections in these patients, obtain procalcitonin levels along with complete blood counts, blood cultures, and other inflammatory markers like C-reactive protein. Values above 0.5 ng/mL suggest possible bacterial infection, while levels exceeding 2.0 ng/mL strongly indicate severe bacterial infection requiring immediate intervention. However, clinicians should not delay antibiotic treatment while waiting for procalcitonin results in patients with suspected serious infection. The value of procalcitonin lies in its specificity for bacterial infections compared to viral ones, and its rapid elevation compared to other markers. This is particularly important in asplenic patients who may develop fulminant sepsis quickly due to their impaired ability to clear encapsulated bacteria from the bloodstream. Some key points to consider when using procalcitonin in post-splenectomy patients include:

• Measuring procalcitonin 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, but not in patients with high clinical probability of bacterial infection 1.
• PCT-guided antibiotic treatment in ICU patients with infection and sepsis patients resulted in improved survival and lower antibiotic treatment duration 1.
• Procalcitonin 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. Remember that clinical judgment remains paramount, as procalcitonin levels must be interpreted within the context of the patient's overall clinical presentation. In addition to procalcitonin, asplenic patients should receive immunization against encapsulated bacteria, and antibiotic prophylaxis should be considered in the event of any sudden onset of unexplained fever, malaise, chills, or other constitutional symptoms 1.

From the Research

Procalcitonin in Post-Splenectomy Infection Assessment

• Procalcitonin (PCT) is a host-response biomarker that has shown clinical value for assessing the likelihood of bacterial infections and guiding antibiotic treatment 2.
• Several trials have found that PCT-guided antibiotic stewardship reduces antibiotic exposure and associated side-effects among patients with respiratory infection and sepsis 2, 3.
• PCT can help differentiate bacterial from non-bacterial infections and inflammation states, particularly in respiratory illness 2.
• Low PCT levels can help rule out bacterial infection in patients with both low pretest probability for bacterial infection and low-risk general condition 2.
• In high-risk individuals and/or high pretest probability for infection, empiric antibiotic treatment is mandatory, and subsequent monitoring of PCT can help track the resolution of infection and guide decisions regarding early termination of antibiotic treatment 2.

Clinical Practice Guidelines and Procalcitonin

• Clinical practice guidelines endorse the use of procalcitonin in differential diagnosis of bacterial infections and/or to monitor antibiotic therapy 4.
• However, the evidence for or against the use of procalcitonin is weak, and more research is needed to fully understand its role in clinical practice 4.
• Procalcitonin-guided antibiotic stewardship protocols have shown appreciable reductions in antibiotic use and duration of therapy in respiratory infections, sepsis, and other infections, with positive effects on clinical outcomes 3.

Procalcitonin in Specific Clinical Settings

• Procalcitonin-guided antibiotic treatment has been shown to be safe and effective in reducing antibiotic use in patients after cardiac surgery 5.
• The use of procalcitonin in other clinical settings, such as post-splenectomy infection assessment, may also be beneficial, but more research is needed to fully understand its role in these settings.

Limitations and Future Directions

• The diagnostic cut-off value of PCT in patients early after surgery remains unclear, and more research is needed to determine the optimal cut-off values for different clinical settings 5.
• The quality of novel PCT assays and their performance in target patient populations across clinically relevant cut-off ranges must be carefully assessed before use in clinical practice 3.