Time to calcitonin normalization after surgery for node-negative and node-positive medullary thyroid cancer.

Calcitonin levels typically normalize within 1 week; and within a fortnight in those with node-positive MTC and preoperative calcitonin levels of 500·1-1000 pg/ml. With node-positive MTC and preoperative calcitonin levels exceeding 1000 pg/ml, and with more than ten nodal metastases, calcitonin normalization takes longer.