Unintentional parathyroidectomy during total thyroidectomy surgery

In this study, we investigated incidental parathyroidectomy during total thyroidectomy surgery that required central lymph node dissection and the potential risk factors. Patients requiring total thyroidectomy and tracheoesophageal groove node dissection were enrolled in the study from January 2013 to June 2015 and we obtained all medical information, including pathology reports. Furthermore, we recorded the parathyroid hormone level in all patients prior to operation and then 3 further times: 1 day, 1 week, and 3 months after surgery. A total of 341 patients (66 male and 275 female) were enrolled in the study. Microscopic examination of postoperative specimens revealed that incidental parathyroidectomy existed in 35 (10.3%) cases: 32 (91.4%) patients had 1 parathyroid gland excised, 3 (8.6%) patients had 2 parathyroid glands excised, and no patients had 3 or more parathyroid glands resected. The mean size of the resected glands was 4.6mm. Parathyroid tissue from 16 (42.1%) cases was located in the intrathyroidal position, 6 glands were located in central lymphatic adipose tissue, and 16 glands were located within or along with thymus tissue. Lateral neck dissection significantly increased the risk of incidental parathyroidectomy (P < 0.001). No other factors including age, sex, and postoperative symptomatic hypocalcemia were significantly associated with incidental parathyroidectomy (all P > 0.05), though incidental parathyroidectomy tended to cause transient hypoparathyroidism (P= 0.051). Therefore, the risk of incidental parathyroidectomy in total thyroidectomy is relatively low; the majority of the resected parathyroid tissue is situated outside the thyroid, therefore we suggest future operations focus on preserving the parathyroid gland when the node dissection is close to the thymus. Incidental parathyroidectomy appears to have an effect on the expression of parathyroid hormone and it is significantly associated with lateral cervical lymph node dissection.