Is procalcitonin of any value in the emergency department? Considering that procalcitonin testing is not available in any of my hospitals, I have never been all that interested in this question. But Swami requested a procalcitonin evidence review for EM:RAP, so I waded through the endless morass of PubMed in his honour.

Procalcitonin is a precursor for calcitonin, the production of which is upregulated in response to inflammatory states.

Unlike other inflammatory markers, procalcitonin elevation is somewhat specific to certain bacterial antigens.

Conversely, viral infections typically result in the production of interferon gamma, which decreases production of procalcitonin.

Therefore, theoretically, procalcitonin might be helpful as an inflammatory marker that could distinguish between viral and bacterial illnesses.

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