Procalcitonin (PCT) is a biomarker that exhibits greater specificity than other proinflammatory markers (e.g., cytokines) in identifying patients with sepsis and can be used in the diagnosis of bacterial infections. A procalcitonin test may be used to help: Diagnose sepsis and other bacterial infections, such as meningitis. Diagnose kidney infections in children with urinary tract infections. Procalcitonin (PCT) is a blood test frequently performed if there is a suspicion of bacterial sepsis, a severe systemic infection that can become life-threatening. The procalcitonin test is an easy way to make the diagnosis quickly and potentially save lives.