Intensive Care Medicine (ICM) Practice Exam 2025 - Free Intensive Care Medicine Practice Questions and Test Prep.

An elevated procalcitonin level in critically ill patients primarily indicates a bacterial infection and is particularly useful in differentiating sepsis from other causes of systemic inflammation. Procalcitonin is a peptide that is produced by various tissues in response to bacterial infection, and its levels significantly increase in the presence of severe bacterial infections and sepsis.

In clinical practice, measuring procalcitonin can guide clinicians in the decision to initiate or discontinue antibiotic therapy. Higher levels of procalcitonin are associated with a greater likelihood of bacterial infection, allowing for better diagnostic and therapeutic strategies. Conversely, if procalcitonin levels are lower, it suggests that the infection may be viral or of a different origin, which helps to refine the diagnosis and manage treatment appropriately.

The other answer choices do not accurately reflect the primary clinical utility of procalcitonin in critically ill patients. While autoimmune reactions, viral infections, and chronic inflammatory diseases can result in elevated markers of inflammation, procalcitonin specifically has its most significant association with bacterial infections, particularly in the context of sepsis diagnosis.