From the Guidelines
Procalcitonin (PCT) is a valuable biomarker for diagnosing bacterial infections and guiding antibiotic therapy in sepsis, with its utility supported by recent guidelines and studies, including those published in 2023 1.
Key Points
- PCT levels rise significantly in bacterial infections but remain low in viral infections or non-infectious inflammatory conditions, making it more specific than traditional markers like C-reactive protein or white blood cell count.
- For sepsis diagnosis, PCT values above 0.5 ng/mL suggest possible bacterial infection, while levels exceeding 2 ng/mL strongly indicate sepsis or severe bacterial infection.
- PCT is particularly useful for antibiotic stewardship, allowing clinicians to safely discontinue antibiotics when levels fall below 0.5 ng/mL or decrease by 80% from peak values, as suggested by recent guidelines 1.
- Serial measurements are more informative than single readings, with declining levels indicating effective treatment.
- PCT is especially valuable in respiratory infections, where levels below 0.25 ng/mL suggest antibiotics can be safely withheld.
Clinical Use
- The use of PCT should be guided by clinical assessment and other diagnostic findings, as false positives can occur in conditions like trauma, surgery, or certain cancers.
- 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.
- The Society of Critical Care Medicine and the Infectious Diseases Society of America guidelines suggest measuring PCT in addition to bedside clinical evaluation in critically ill patients with a new fever and no clear focus of infection, if the probability of bacterial infection is deemed low to intermediate 1.
Limitations
- PCT levels can be elevated during severe viral illness, including influenza and COVID-19, potentially making the discriminating power for predicting the causative microorganisms less useful 1.
- The diagnostic accuracy and specificity of PCT are higher than those of CRP, but further studies are needed to define the optimal cutoff points for PCT and CRP and the diagnostic indexes in different disease stages 1.
From the Research
Utility of Procalcitonin
- Procalcitonin (PCT) is a biomarker that has been shown to be useful in diagnosing and managing sepsis and bacterial infections 2, 3, 4, 5, 6.
- PCT has been demonstrated to have superior diagnostic accuracy for a variety of infections, including sepsis, compared to other biomarkers 2, 3.
- The use of PCT can help guide antibiotic therapy, reducing unnecessary antimicrobial treatment and promoting antibiotic stewardship 4, 5.
Diagnostic Utility
- PCT can be used to differentiate between bacterial and viral inflammations, with rapidly available results 5, 6.
- PCT has been shown to be more specific for sepsis and bacterial infection than other biomarkers, such as CRP 6.
- PCT starts to rise earlier and returns to normal concentration more rapidly than CRP, allowing for an earlier diagnosis and better monitoring of disease progression 6.
Clinical Applications
- PCT can be used in a variety of clinical settings, including primary care, emergency department, and intensive care 6.
- PCT measurement can aid in the diagnosis of sepsis and guide and monitor antibiotic therapy 6.
- The use of PCT can help reduce the overuse of antibiotic therapy, decreasing the risk of side effects and emerging bacterial multiresistance 4, 5.
Limitations
- PCT is not a universal and perfect biomarker, as it can also be increased in noninfectious disease conditions 2.
- The interpretation of PCT levels must always comprise the clinical setting and knowledge about assay characteristics 4.
- Further research is needed to understand the optimal use of PCT, also in combination with other emerging diagnostic tests for most efficient sepsis care 5.