High incidence of chronic hypoparathyroidism secondary to total thyroidectomy

INTRODUCTION: Hypoparathyroidism (HypoPT) is the most common complication after total thyroidectomy (TT). Recent literature report incidences of HypoPT that are higher than previously anticipated. This study aimed to assess the incidence of transient and chronic HypoPT in patients undergoing TT and to specify risk factors and recovery time.

METHODS: This was a retrospective review of patients undergoing TT in the period from 2013 to 2018 due to benign thyroid disease in a Danish university hospital. In total, 187 patients were eligible for inclusion. Data were collected from internal medical files, the Thykir database sheets and patient records. HypoPT was defined as SE-ionised-Ca2+ levels (Less than 1.16 mmol/l) and inappropriately low parathyroid hormone levels.

RESULTS: The incidence of transient and chronic HypoPT was 81 (43.3%) and 25 (13.4%), respectively. Younger ages and toxic indication for surgery were independent risk factors for transient and chronic HypoPT. Incidences in Graves' disease population were 70.5% and 27.3%, respectively. Resolution within the first months was seen in 48.2% of the patients with acute transient HypoPT.

CONCLUSIONS: The incidence of chronic HypoPT after TT is higher than previously reported. This is primarily due to a lack of consistency in the definition and follow-up time between studies. Younger patients and those with a toxic indication for surgery are at higher risk of HypoPT after TT than other patients.

FUNDING: none.

TRIAL REGISTRATION: The study was approved by the Danish Data Protection Agency (REG-015-2019) and The Ethical Committee of Central Denmark (No. 66792).