Procalcitonin is the prohormone for calcitonin. It is modified in the parathyroid gland to the active hormone and not normally released into the circulation. It is, however, present in the blood in certain inflammatory states.
Studies in patients with various infections indicate that it is a useful marker. Major areas of investigation have been in patients with sepsis and pneumonia. Lack of immediate availability in many community hospitals limits its usefulness at present.
In patients with pneumonia it is a useful prognostic indicator. It also shows promise in differentiating bacterial pneumonia from viral infections. Consequently it has shown promise in guiding antibiotic therapy. In this study patients whose antibiotic therapy was guided by procalcitonin measurements were able to be treated with fewer instances and shorter courses of antibiotic therapy than controls with no difference in outcomes.
With further research and eventual availability at the point of care procalcitonin measurement is likely to emerge as a useful tool for management decisions in patients with pneumonia and sepsis.