Factors contributing to unintentional parathyroidectomy during thyroid surgery

Unintentional parathyroidectomy during thyroid surgery has an incidence ranging between 1% and 31% across institutions. Many studies have identified malignancy and central neck dissection as risk factors for losing parathyroid glands, but few studies have evaluated the impact of other factors such as lymphocytic thyroiditis, hyperthyroidism, or concomitant primary hyperparathyroidism. The purpose of this study was to investigate which factors contribute to parathyroid loss during thyroid surgery. Charts of 269 patients undergoing thyroid surgery at a tertiary care medical center from 2010 to 2013 were retrospectively reviewed. Sixty-six patients (24.5%) experienced unintentional parathyroidectomy. Bivariate analysis showed no significant differences in patient characteristics. Patients with unintentional parathyroid removal had a significantly smaller largest thyroid nodule size (P = 0.002), higher rate of central neck dissection (30.3% vs 7.9%, P < 0.0001), and higher rate of malignancy (50% vs 36.0%, P = 0.04). Multivariable analysis showed that the strongest risk factor for unintentional parathyroidectomy was central neck dissection (P = 0.0008; odds ratio 4.72, confidence interval 1.91-11.71). In conclusion, central neck dissection for thyroid malignancy is the strongest risk factor for unintentional thyroidectomy. The presence of concomitant primary hyperparathyroidism, lymphocytic thyroiditis, or hyperthyroidism did not appear to increase the risk of unintentional parathyroidectomy.