PCT(procalcitonin) is a protein that rises in plasma when it is infected with severe bacteria, fungi, parasites, and sepsis and multiple organ failure. PCT does not increase in autoimmune, allergic, and viral infections.
Locally limited bacterial infections, mild infections, and chronic inflammation do not cause elevation. Bacterial endotoxin plays a crucial role in the induction process.
PCT reflects the activity of the systemic inflammatory response. Factors affecting PCT levels include the size and type of infected organs, the type of bacteria, the degree of inflammation, and the state of the immune response. In addition, PCT can only be measured 1 to 4 days after major surgery in a small number of patients.