CALCA and Shock: Serum PCT is a well-established biomarker for distinguishing bacterial from nonbacterial infections and is widely used for therapeutic decision-making and antibiotic stewardship.[6,8,9] The highest PCT levels are observed in patients with systemic bacterial infection and sepsis, which is defined as “life-threatening organ dysfunction caused by a dysregulated host response to infection,” or septic shock, which can be clinically identified by the requirement for vasopressors to increase the mean arterial blood pressure despite fluid resuscitation.[7,8]