Asymptomatic Medullary Thyroid Carcinoma With Isolated Carcinoembryonic Antigen Elevation in a Patient With Chronic Kidney Disease: A Case Report.

Medullary thyroid carcinoma (MTC) is rare and typically presents with a palpable nodule. We report a 64-year-old asymptomatic woman with chronic kidney disease (CKD) diagnosed with MTC after incidental procalcitonin elevation on routine labs, highlighting procalcitonin as an atypical clue and the need to distinguish tumor-related from CKD-related hypercalcitoninemia.