Medullary thyroid carcinoma without marked elevation of calcitonin: a diagnostic and surveillance dilemma.

Calcitonin is a sensitive tumor marker for medullary thyroid cancer (MTC) and is useful in preoperative diagnosis and postoperative surveillance for recurrent disease. Calcitonin-negative MTC is a rare occurrence. We present the case of a 68-year-old man with a 6.5 cm sporadic MTC with a 5-cm metastasis in the neck, but only minimally elevated serum calcitonin levels. He underwent total thyroidectomy, resection of internal jugular vein, and limited ipsilateral lymph node dissection. He remains disease-free 12 months after surgery. We review the literature on calcitonin-negative MTC and discuss methods of postoperative surveillance in this subset of patients.