The normal value of calcitoninogen is mainly determined by the method of immunoassay, if the colloidal gold colorimetric method is applied, the normal value is less than 0.5 ng/mL. if the immunohistochemical luminescence method is used, the low value should be less than 0.1 pg/mL, and if the radioimmunological analysis is used, the sensitivity of the test can reach 4 pg/mL. calcitoninogen is a protein that is elevated in plasma when there is a serious infection, fungus or parasites, and in multiple organ failure such as sepsis, plasma levels are elevated. Calcitoninogen is not elevated in autoimmune allergies or viral infections, nor is it elevated in limited infections, mild infections, or chronic inflammation, so it is important to help in the clinical diagnosis of infections.