The serum PCT concentration is 0.01-0.05 ng/mL under normal conditions, and the PCT level rises significantly within 2-6 hours after bacterial infection, so it can be used as a predictor of bacterial infection, however, it has some limitations, and it is not specifically up-regulated in major surgery, early post-operative period, trauma, severe burns, inhalation injuries, heatstroke, acute pancreatitis, and cardiac arrest-induced hypothermia and other massive inflammatory states (Choi and McCarthy, 2018; Xu et al., 2022). Here, CALCA is linked to bacterial infectious disease.