Persistent hyperprocalcitoninemia as the initial diagnostic clue to sporadic medullary thyroid carcinoma

Persistent elevation of procalcitonin in the absence of infection should raise suspicion for medullary thyroid carcinoma and other neuroendocrine malignancies.Procalcitonin may serve as a useful adjunct biomarker alongside calcitonin in the diagnostic evaluation and postoperative follow-up of medullary thyroid carcinoma.Awareness of non-infectious causes of hyperprocalcitoninemia can prevent unnecessary antimicrobial therapy and reduce diagnostic delay in internal medicine practice.