Calcitoninogen, it is a protein. It is elevated in plasma levels in severe bacterial, fungal, and parasitic infections, as well as in sepsis, and in multiple organ failure. Calcitoninogen is not elevated in autoimmune hypersensitivity and also in viral infections, localized limited bacterial infections, minor infections and chronic inflammation do not lead to its elevation. Bacterial endotoxins play a crucial role in the induction process. Calcitoninogen it reflects the activity of the systemic inflammatory response. Factors that influence calcitoninogen levels include, the size and type of the infected organ, the type of bacteria, the degree of inflammation and the status of the immune response. In addition calcitoninogen can only be measured in surgical patients 1 to 4 days after major surgical procedures. Also elevated calcitonin levels are seen in severe shock, systemic inflammatory response syndrome (SIRS) and multiorgan dysfunction syndrome (MODS), even in the absence of bacterial infection or bacterial lesions, but in these cases calcitonin levels are usually lower than in those patients with bacterial lesions. The release of cytokines or bacterial translocation from the intestine may cause induction. It is a parameter for the diagnosis and monitoring of bacterial inflammatory index infections, as an acute parameter for the differential diagnosis of bacterial and non-acute infections and inflammations, as well as for the assessment of the clinical course of severe inflammatory diseases and the prognosis, among others.