Procalcitonin and neopterin in infectious diseases

Abstract

Procalcitonin, a new inflammation parameter, has been shown to be markedly increased in patients with severe bacterial and parasitic infections, septic shock, and multiple organ failure. In contrast, in severe viral infections or inflammatory reactions of non-infectious origin (e.g. toxic acute respiratory distress syndrome or toxic pancreatitis) as well as in autoimmune disorders, there is little or moderate increase of procalcitonin serum levels. Therefore procalcitonin may be used for differential diagnosis of bacterial versus non-bacterial inflammation. Furthermore, procalcitonin correlates with the severity of infection and sepsis and it is considered to be a valid parameter for monitoring both the severity and the course of sepsis and multiple organ failure as well as the success of surgical and intensive therapy in critically ill patients. Neopterin production is closely associated with activation of the cellular immune system. High neopterin levels are found in several inflammatory diseases and certain malignancies. Neopterin measurements are useful for monitoring allograft recipients to detect immunological complications. In autoimmune diseases, neopterin concentrations reflect the extent and activity of disease. In infectious diseases, neopterin helps in the differential diagnosis of acute viral and bacterial infections and provides prognostic information in human immunodeficiency virus disease and in patients with multiple trauma and sepsis. In this article the clinical application of procalcitonin and neopterin in infectious diseases is reviewed, and special emphasis is given to clinical situations in which the combined determination of both parameters, neopterin and procalcitonin, is able to support differential diagnosis.