CALCA and Sepsis: Elevation of the serum PCT concentration is a more sensitive marker than the white blood cell (WBC) count and C-reactive protein (CRP) level in the early identification of bacterial infection and sepsis in adults and children3, 4, 5, 6, 7, 8, 9, 10, because PCT is released into the blood several hours after infection onset1, 2, 11, 12.