The main cause of high calcitoninogen in newborns is a bacterial infection. High calcitoninogen is often due to a severe bacterial infection, which normally results in very low calcitoninogen in the blood. If the infection is viral, the calcitoninogen in the blood is also significantly low. Only bacterial infections that are severe will result in high levels of calcitoninogen in the blood. Therefore, calcitoninogen can effectively identify whether the infection is bacterial or viral in origin. In summary, a significantly high calcitoninogen in newborns is often indicative of a serious bacterial infection, especially in neonates with sepsis. In this case, anti-infective treatment such as cephalosporin should be applied promptly.