BACKGROUND: Postoperative hypoparathyroidism is a common complication following total thyroidectomy. The aim of this study was to investigate the incidence of both transient and permanent hypoparathyroidism in patients undergoing total thyroidectomy in a tertiary referral centre and, furthermore, to identify early predictive risk factors.

METHODS: Based on a single-institution retrospective review, we identified 582 patients who underwent total thyroidectomy between January 2010 and March 2015. Information on age, gender, pathological diagnosis, duration of surgery, autotransplantation of parathyroid glands, neck dissection, and experience and position of the surgeon was retrieved from the medical records. Furthermore, serum levels of parathyroid hormone and calcium were registered pre- and postoperatively and after 3 and 12 months.

RESULTS: The incidence of transient hypoparathyroidism during the first 24 h and 3 months after surgery was 47.8 and 17.8%, respectively. Furthermore, the incidence of permanent hypoparathyroidism 1 year after surgery was 10.7%. A prolonged duration of surgery was significantly associated with hypoparathyroidism. Moreover, autotransplantation of parathyroid glands was a significant predictor of transient hypoparathyroidism after 24 h and 3 months, but was not associated with permanent hypoparathyroidism.

CONCLUSIONS: Transient and permanent hypoparathyroidism is common among patients undergoing total thyroidectomy in a tertiary referral centre. A duration of surgery >120 min constitutes an independent risk factor due to the risk of ischaemic damage. Regain of function of devascularized parathyroid glands must be expected to last at least 1 year postoperatively. Furthermore, the recovery of autotransplanted parathyroid glands should not be evaluated within 1-3 months after surgery.