Identifying risk factors for hypoparathyroidism following totalthyroidectomy in patients with persistent or relapsed Graves’ disease

Abstract

Objective This article reviews the etiologies, clinical presentations, investigations, imaging, and treatments of Graves’ disease (GD). Total thyroidectomy (TT) is the preferred procedure to manage medically-refractory GD although its major weakness is postoperative hypoparathyroidism. This study aimed to identify the incidence rate of postoperative hypoparathyroidism, the associated risk factors and possible reasons. Strategies in reducing this complication are also elaborated. Patients and Method We retrospectively identified patients who underwent a TT for GD by one surgical team at our institution from 1998 to 2014, all of which were observed one night and followed-up for at least 12 months. If necessary, oral supplements were initially given 2-3 weeks after TT and lasted for 4-6 weeks, then PTH and Ca were re-tested every 4-8 weeks until serum calcium is normal without supplements. We calculate the rate of temporary and permanent hypoparathyroidism, compare patients’ characteristics in the normocalcemia and hypocalcemia group both within 24 hours and after 6 months of surgeries. Chi-square tests, Fisher’s exact tests and Mann–Whitney U are used to analyze those data. Results 627 of 716 total patients can be analyzed. Within 24 hours of surgery, 133 (21.2%) patients developed hypocalcemia, including 30 (22.6%) patients with symptoms and 103 (77.4%) patients without symptoms. 92 (14.7%) patients had temporary hypoparathyroidism while 41 (6.5%) patients had permanent hypoparathyroidism. There was significant difference (p-value <0.05) in Carbimazole dose, gland weight, serum 25-hydroxyvitamin D, PTH taken on day-0 and day-1, and hospital stay between the normocalcemia and ahypocalcemia group. Significant difference was also found in PTH taken on day-0 and day-1 between the two groups after 6 months of TT. Conclusion Temporary hypoparathyroidism is common after TT in GD. Patient and disease characteristics influenced the rate of hypoparathyroidism.