Procalcitonin-Guided Antibiotic Therapy
Background: Cutoffs for Procalcitonin Used in Clinical Practice
In healthy people, procalcitonin levels are very low. In systemic bacterial infections, including sepsis, procalcitonin levels are generally ≥0.5 ng/mL; higher levels correlate with the severity of illness and prognosis. Studies indicate that procalcitonin is superior to C-reactive protein, interleukin-6, and interleukin-8 for diagnosing sepsis.
Procalcitonin levels in patients with suspected respiratory tract infection (RTI) may be useful in determining if patients require antibiotic therapy. In patients with RTIs, the levels of procalcitonin are not necessarily as elevated; a cutoff >0.25 ng/mL seems to be most predictive of a bacterial RTI requiring antibiotic therapy, while a level <0.25 ng/mL signals resolution of the infection.
In neonates, there is normally a characteristic increase in procalcitonin after birth, with a rapid return to normal by 48 to 72 hours. In this circumstance, the elevated procalcitonin levels are an acute-phase reactant in response to the stress of the birth process, yet an incremental increase is still detectable in infants with neonatal sepsis. A nomogram for procalcitonin cutoffs that accounts for the time from birth in hours is recommended.
In postoperative patients, the stress of surgery may increase procalcitonin levels; however, the increase in procalcitonin in patients with infection, including those with a subclinical infection or those at high risk of infection, is incremental. Postoperatively, the procalcitonin cutoff level to identify patients with infection or at risk of infection may be higher than that used for other patient groups due to cytokine release during surgery.
- Soni NJ, Samson DJ, Galaydick JL, et al. Procalcitonin-Guided Antibiotic Therapy. Comparative Effectiveness Review No. 78 (Prepared by the Blue Cross and Blue Shield Association Technology Evaluation Center Evidence-based Practice Center under Contract No. HHSA 290-2007-10058-I). Rockville, MD: Agency for Healthcare Research and Quality; August 2012. AHRQ Publication No. 12-EHC124-EF. Available at www.effectivehealthcare.ahrq.gov/procalcitonin.cfm.
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- Christ-Crain M, Müller B. Biomarkers in respiratory tract infections: diagnostic guides to antibiotic prescription, prognostic markers and mediators. Eur Respir J 2007 Sep;30(3):556-73. PMID: 17766633.
- Luyt CE, Guérin V, Combes A, et al. Procalcitonin kinetics as a prognostic marker of ventilator-associated pneumonia. Am J Respir Crit Care Med 2005 Jan 1;171(1):48-53. PMID: 15447947.
- Simon L, Gauvin F, Amre DK, et al. Serum procalcitonin and C-reactive protein levels as markers of bacterial infection: a systematic review and meta-analysis. Clin Infect Dis 2004 Jul 15;39(2):206-17. PMID: 15307030.
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