PCT(Procalcitonin) is a peptide precursor of the hormone calcitonin. Measurement of PCT can be used as an authoritative marker for diagnosis and stratification of sepsis.

Clinical Significance

It is well-documented that early diagnosis of a bacterial infection can lead to a decrease in mortality and morbidity among all patients. Efficient diagnosis of bacterial infections allows physicians to initiate antibiotic therapy when it is deemed appropriate, thus preventing the misuse and overuse of antibiotics. As antibiotic resistance continues to rise, it has become ever more important for clinicians to determine different algorithms and laboratory tests that help sustain current antibiotic parameters.  Procalcitonin serum assays have been developed to provide physicians and nurses with an earlier detection method for determining the origin of a systemic inflammatory response (eg, bacterial versus non-bacterial). Early detection, in turn, limits the development of antibacterial resistance as well as patient exposure to antibiotics when they are no longer warranted. 
The prognostic value of procalcitonin has also shown clinical significance by providing physicians with a positive correlation between disease severity and elevated PCT serum levels, especially within septic patients.