A procalcitonin (PCT) test is a type of blood test that measures the level of procalcitonin in the blood. Procalcitonin is a protein that is released in response to bacterial infections and can be used to differentiate the etiology of infectious processes. The test is useful in helping to detect sepsis and severe bacterial infections in the early stages and to distinguish between a bacterial and viral infection.

A PCT test can help healthcare providers diagnose if a person has sepsis from a bacterial infection or if they have a high risk of developing sepsis. Sepsis is a life-threatening condition that occurs when the bodys response to an infection damages its own tissues and organs. A high level of procalcitonin in the blood means that a person most likely has sepsis, may have a high risk of developing severe sepsis and septic shock, or may have a serious systemic bacterial infection that increases their risk for sepsis.

Other tests that may be done in conjunction with a PCT test include cultures, complete blood count, lactate, blood gases, comprehensive metabolic panel, prothrombin time, partial thromboplastin time, and C-reactive protein. The time it takes to get PCT test results depends on the laboratory performing the testing, but results may be available within an hour or so.

It is important to note that there is very little risk to having a blood test, and any symptoms such as slight pain or bruising at the spot where the needle was put in usually go away quickly.