Inadvertent parathyroidectomy during thyroid surgery

Introduction: Inadvertent parathyroidectomy is a recognised complication of thyroid surgery. We aimed to investigate the incidence of and risk factors for inadvertent parathyroidectomy during thyroid surgery, in our patient cohort. Methods: A retrospective review of the records of all patients undergoing thyroid surgery in our institution between January 2012 and December 2014 was performed. Medical records, laboratory investigations and histopathology reports were evaluated. Patient demographics, indication for surgery, surgery performed, final pathology, incidental parathyroidectomy and post-operative hypocalcaemia were recorded. Univariate analysis using the Fisher’s exact test was performed. Results: Two hundred and thirty procedures were included: 147 hemi-thyroidectomies and 83 total thyroidectomies. Central neck dissection was also performed in 13 cases. The most common indication for surgery was indeterminate cytology (81 cases). Post-operatively, malignant disease was reported in 52 cases (22.6%). Inadvertent parathyroidectomy occurred in 40 cases (17.3%). There was a statistically significant increased risk of inadvertent parathyroidectomy with malignant disease (p = 0.001) and after central neck dissection (p = 0.013) but no difference was seen between hemi- and total thyroidectomies (p = 0.47), gender (p = 1.00) or with increasing age (p = 1.00). Hypocalcaemia occurred in four cases and was transient in three. Conclusion: Inadvertent parathyroidectomy is a potential risk during thyroid surgery but post-operative hypocalcaemia as a result is rare. Malignancy and more extensive surgery appear to carry an increased risk for this complication.