Procalcitonin (PCT), a protein that consists of 116 amino acids, is the peptide precursor of calcitonin, a hormone that is synthesized by the parafollicular C cells of the thyroid and involved in calcium homeostasis. Procalcitonin arises from endopeptidase-cleaved preprocalcitonin. In current clinical practice, procalcitonin (PCT) has developed into a promising new biomarker for the early detection of systemic bacterial infections. PCT is a 116-amino acid residue first explained by Le Moullec et al. in 1984; its diagnostic significance was not recognized until 1993.[1] In 1993, Assicot et al. demonstrated a positive correlation between high serum levels of PCT and patients with positive findings for bacterial infection and sepsis (e.g., positive blood cultures ... Procalcitonin is the propeptide of calcitonin, a 116-peptide molecule with a molecular weight of 13 kDa. Procalcitonin has been studied as a sepsis biomarker, to help with diagnosing/ ruling out sepsis and to guide the initiation and cessation of antibiotics A procalcitonin test measures the level of procalcitonin in your blood. A high level may be a sign of sepsis, a life-threatening condition. Learn more.