A procalcitonin test measures the level of procalcitonin in your blood. A high level could signify a serious bacterial infection, such as sepsis. Sepsis is the body's severe response to infection. Sepsis happens when an infection in one area of your body, such as your skin or urinary tract, spreads into your bloodstream. This triggers an extreme immune reaction. It can cause a rapid heartbeat, shortness of breath, decreased blood pressure, and other symptoms. Without quick treatment, sepsis can lead to organ failure or even death.