The role of thymus preservation in parathyroid gland function and surgical completeness after bilateral central lymph node dissection for papillary thyroid cancer: a randomized controlled study.

•Thymus preservation during total thyroidectomy with CLND had benefits on parathyroid gland protection.•Thymus preservation had no effects on oncologic completeness of total thyroidectomy with bilateral CLND.•Thymus preservation should be performed during bilateral CLND unless there are suspicious lymph nodes around thymus.