What is Procalcitonin (as calcitonin precursor; distinct from the sepsis marker)?
Procalcitonin is the prohormone from which mature calcitonin is cleaved. Some medullary thyroid carcinomas, particularly poorly differentiated tumours, secrete procalcitonin and related peptides disproportionately to mature calcitonin, and procalcitonin is biologically more stable. It is occasionally measured to resolve discordant or borderline calcitonin results, and should not be conflated with the identically named inflammatory and sepsis biomarker, which reflects a different tissue source.