From the Guidelines
Order procalcitonin (PCT) primarily for patients with suspected sepsis, lower respiratory tract infections like pneumonia, or when trying to differentiate between bacterial and viral infections, as it can help guide antibiotic initiation and discontinuation, especially in emergency departments and intensive care settings 1. When evaluating patients with suspected infections, PCT testing can be valuable in determining the need for antibiotics. The test is most useful in settings where rapid decisions about antibiotic therapy are crucial.
- PCT levels above 0.5 ng/mL suggest bacterial infection, while levels below 0.25 ng/mL make bacterial infection less likely 1.
- Serial PCT measurements can help guide antibiotic discontinuation, as declining levels (especially drops of >80% from peak) suggest resolving infection 1.
- PCT has limitations, including elevation in non-infectious conditions like trauma, surgery, and certain cancers, and may not rise significantly with localized infections or infections caused by atypical pathogens 1.
- A recent systematic review and meta-analysis demonstrated that PCT-guided antibiotic treatment in ICU patients with infection and sepsis patients resulted in improved survival and lower antibiotic treatment duration 1.
- The European Society of Clinical Microbiology and Infectious Diseases guidelines suggest the use of procalcitonin in the ED to guide the initiation of antibiotics for patients with suspected LRTI who are likely to be admitted to the hospital, with a weak recommendation and moderate certainty of evidence 2.
- PCT should complement clinical judgment rather than replace it, as no single biomarker is perfect for diagnosing infections 1.
- Using PCT appropriately can reduce unnecessary antibiotic use, decrease antibiotic duration, and potentially improve patient outcomes while combating antimicrobial resistance 1.
From the Research
When to Order Procalcitonin
Procalcitonin (PCT) is a biomarker used to guide antibiotic therapy in patients with suspected infections. The decision to order PCT should be based on the following considerations:
- Clinical presentation: PCT is useful in differentiating bacterial infections from non-infectious causes of systemic inflammatory response syndrome (SIRS) 3.
- Patient population: PCT can be used in various patient populations, including those with acute respiratory tract infections, sepsis, and septic shock 4, 5, 6.
- Antibiotic therapy: PCT can help guide the initiation and duration of antibiotic therapy, reducing the risk of antibiotic overuse and resistance 4, 5, 6.
Indications for Procalcitonin Measurement
The following are indications for measuring PCT:
- Suspected bacterial infection: PCT can help diagnose bacterial infections and guide antibiotic therapy 7, 4, 5.
- Sepsis or septic shock: PCT can help differentiate sepsis from non-infectious causes of SIRS and guide antibiotic therapy 3, 6.
- Acute respiratory tract infections: PCT can help guide antibiotic therapy in patients with acute respiratory tract infections 4, 5.
Interpretation of Procalcitonin Results
When interpreting PCT results, consider the following:
- Threshold values: Higher thresholds for diagnosing infection or de-escalating therapy should be considered in special populations, such as those with renal dysfunction or immunosuppression 7.
- Clinical context: PCT results should be considered in the context of clinical presentation, medical history, and other laboratory results 7, 3.
- Serial measurements: Serial PCT measurements can help guide antibiotic therapy and reduce antibiotic exposure 6.