Procalcitonin: Importance for the diagnosis of bacterial infections

In contrast to calcitonin, which is primarily synthesized in the thyroid, procalcitonin is a prohormone which is synthesized in many different tissues of infected organs. To diagnose mild, localized, or early infections an assay needs to have a functional assay sensitivity of approximately 0.02 mu g/L. We demonstrated that procalcitonin modifies the outcome of respiratory infections with regard to minimizing the use of antibiotics and duration of antibiotic treatment. High concentrations, especially over time, indicate high risk of a severe outcome. In this respect, procalcitonin is superior to other infection markers, such as C-reactive protein. High procalcitonin levels can also be found in non-bacterial diseases, such as malaria, severe trauma, burns, and medullar carcinoma of the thyroid. Procalcitonin, as a marker, has improved the diagnosis of bacterial infections. However, procalcitonin needs to be used in conjunction with other laboratory markers, clinical examination, and medical history.