Procalcitonin is a protein that is produced by the body in response to bacterial infections. It is a biomarker that helps doctors determine the presence and severity of infections, particularly in cases of sepsis. Elevated levels of procalcitonin in the blood can indicate a significant bacterial infection, guiding treatment decisions. Testing for procalcitonin is often used in emergency and critical care settings. It can help differentiate between bacterial and viral infections, which is important for appropriate antibiotic use. Lower levels of procalcitonin may suggest a viral infection or a non-infectious cause of symptoms, aiding in more accurate diagnoses.