From the Guidelines
Elevated procalcitonin (PCT) levels are indicative of a systemic bacterial infection, and in such cases, antimicrobial therapy should be initiated promptly [ 1 ].
Key Points
- For patients with suspected sepsis, empiric antibiotic therapy with meropenem 1g IV every 8 hours or piperacillin-tazobactam 4.5g IV every 6 hours may be considered [ 1 ].
- The duration of antibiotic therapy should be tailored to the individual patient's response, but typically ranges from 7-14 days, with procalcitonin levels monitored daily to guide therapy discontinuation when levels decrease to less than 0.25 ng/mL [ 1 ].
- PCT levels can be used to guide antibiotic discontinuation, with levels of less than 0.5 µg/L or a decrease of greater than or equal to 80% from peak levels indicating potential discontinuation [ 1 ].
Considerations
- PCT is a precursor hormone of calcitonin produced by the parafollicular cells of the thyroid gland and neuroendocrine cells of the lung and the intestine, and its levels are associated with the severity of the infection [ 1 ].
- PCT levels begin to rise four hours after exposure to bacteria, reaching a maximum level after six to eight hours [ 1 ].
- The use of PCT-guided antibiotic treatment in ICU patients with infection and sepsis has been shown to improve survival and reduce antibiotic treatment duration [ 1 , 1 , 1 ].
From the Research
Significance of Elevated Procalcitonin (PCT) Levels
Elevated procalcitonin (PCT) levels are significant in the diagnosis and management of various conditions, including:
- Bacterial infections: PCT levels increase reliably in response to bacterial infection, making it a useful biomarker for diagnosing sepsis and guiding antibiotic therapy 2, 3, 4, 5, 6
- Sepsis: PCT levels can help differentiate sepsis from non-infectious systemic inflammatory response syndrome (SIRS) 2, 6
- Antibiotic therapy: PCT-guided antibiotic therapy can help reduce the duration of antibiotic treatment and hospital admission without adversely affecting outcomes 3, 5
- Mortality prediction: Elevated PCT levels are associated with increased mortality in critically ill patients 6
Clinical Applications of PCT
PCT has various clinical applications, including:
- Diagnosing invasive bacterial infection in children 4
- Guiding antibiotic therapy in special patient populations, such as those with renal dysfunction, cardiac compromise, or immunocompromised states 3
- Monitoring response to antimicrobial therapy 2
- Diagnosing secondary inflammations and renal involvement in pediatric urinary tract infections 2
Interpretation of PCT Levels
PCT levels should be interpreted in conjunction with clinical criteria, as they can be elevated in non-bacterial inflammatory processes and may not be effective in distinguishing between bacterial and viral infections 2, 3, 5. Typical values for maximal sensitivity and specificity are: