摘要Background:To observe the changes in serum calcitonin levels after application of different surgical methods for primary medullary thy-roid microcarcinoma (MTMC) and explore a more reasonable surgical method.Methods:A retrospective analysis of 36 patients with MTMC,16 in group A and 20 in group B,was performed.In group A,tumors were single and confined to the thyroid lobe,and thyroid lobectomy with isthmusectomy was performed.In group B,tumors were in the isthmus or invaded the thyroid gland,or there were multiple foci in bilateral lobes,and patients with primary foci underwent total thyroidectomy.The median follow-up time was 3.6 years.Clinical and pathological characteristics and changes in serum calcitonin (CTn) and carcinoembryonic antigen levels after the surgery were compared between the 2 groups.Results:The difference in the biochemical cure rate after surgery was statistically significant between patients with preoperative serum calcitonin levels<150 pg/mL and ≥150 pg/mL (P<0.01).No significant differences in the biochemical cure rates and serum calcitonin levels were noted at different time points after surgery between group A and group B (P>0.05).One recurrence and metastasis were ob-served in each group after surgery.Conclusions:After performing different surgical methods for the primary foci of MTMC,the changes in serum calcitonin and carcinoembryonic antigen levels are similar.Especially for patients with single foci confined to the thyroid lobe without lateral cervical lymph node metastasis and with serum calcitonin levels<150 pg/mL,the unilateral thyroid lobectomy with isthmectomy can achieve the same therapeutic effect and biochemical cure rate as total thyroidectomy.