Procalcitonin - potential, limitations and availability

Bacterial infections and sepsis are major problems in critically ill patients. Timely diagnosis and therapy reduce morbidity and mortality. Many studies have included the investigation of various biomarkers whose elevated concentrations can indi cate sepsis; among them, PCT proved to be most useful. PCT is synthesized in the thyroid gland as a prohormone of calcitonin. In healthy individuals the PCT concentration is <0.1 ng/mL. The advantage of the PCT is a high nega tive predictive value for the exclusion of sepsis, with the cut-off value of 0.5 ng/ml. A concentration between 2 and 10 ng/ml indicates strong sepsis, whereas a value ≥10 ng/ml is associated with septic shock. In addition to the diagnosis of sepsis, the measurement of PCT concentration is use ful for the introduction and monitoring of antibiotic therapy, which is performed ac cording to an algorithm based on the cutoff value for PCT. Immunoassays are used to measure PCT concentrations in serum or plasma. It is possible to determine the concentration in whole blood by using point-of-care testing. In pathological conditions that are not associated with sepsis, PCT is useful as a prognostic indicator of disease complica tions. Some studies suggest that PCT is a potential early indicator of acute coronary syndrome.