Uses of Procalcitonin as a Biomarker in Critical Care Medicine.

Procalcitonin is a commonly used biomarker for infection and severity in the intensive care unit. Although relatively specific for bacterial, as opposed to viral, infections, serum procalcitonin levels also correlate with disease severity and thus cannot reliably distinguish between bacterial and nonbacterial infections in the setting of critical illness, particularly in cases of severe influenza and coronavirus disease-2019. Baseline procalcitonin levels are insufficiently discriminative to permit the withholding of antibiotics in patients with critical illness and suspected sepsis. Trends in procalcitonin levels over time, however, give us the opportunity to individualize the duration of antibiotics without negative impacts on mortality.