Procalcitonin
BiomarkerAlso known as: PCT, Pro-Calcitonin
Calcitonin PrecursorsResearch phase: Clinical (diagnostic biomarker)Regulatory: FDA-cleared as diagnostic biomarker for bacterial infection and sepsis.
Mechanism
Procalcitonin is the precursor of calcitonin that surges in the blood during bacterial infections. It is widely used in hospitals to diagnose bacterial infections and guide antibiotic decisions.
Technical detail
Procalcitonin (PCT) is the 116-amino acid precursor of calcitonin, normally processed to mature calcitonin in thyroid C-cells only. During bacterial infection, PCT is produced ubiquitously (liver, lung, adipocytes, monocytes) induced by bacterial endotoxin and IL-1β/TNF-α, while viral infections suppress PCT via IFN-γ. Serum PCT >0.5 ng/mL strongly suggests bacterial infection. FDA-cleared assays guide antibiotic initiation/discontinuation in sepsis and lower respiratory tract infections.