CRP and infection: Bacterial toxin mediated production of inflammatory cytokines stimulates other organs like kidneys, liver, lungs, fat and muscles to release PCT into bloodstream.9 However, PCT is not released in viral infections as increased concentration of interferon γ in viral infections suppresses secretion of procalcitinin.10 PCT levels rise early in course of infection, remain high for 8-24 hours and then return to normal earlier than CRP.7 PCT has highest sensitivity and specificity for predicting systemic bacterial infection in adults.