Procalcitonin Infection Test - Procalcitonin Test

The procalcitonin (PCT) test is a quantitative measurement of the serum level of the peptide procalcitonin. Procalcitonin is a precursor to the hormone calcitonin, and its blood levels are normally very low. During severe systemic bacterial infections (sepsis), many tissues (especially outside the thyroid gland) produce large amounts of it, leading to a sharp increase in its blood level. It rises less dramatically in viral infections or non-infectious inflammations, making it a useful differential marker.