Association between the location of the parathyroid glands and the risk of postoperative hypocalcemia and hypoparathyroidism following thyroidectomy

Background: Postoperative hypocalcemia after total thyroidectomy is associated with injury, inadvertent removal, or devascularization of the parathyroid glands; however, the role of their anatomical position relative to the thyroid capsule remains poorly characterized. Objective: To evaluate the association between the anatomical position of the parathyroid glands (intracapsular or extracapsular) and the risk of postoperative hypocalcemia and hypoparathyroidism after total thyroidectomy. Material and methods: A single-center retrospective study including patients who underwent total thyroidectomy between 2013 and 2017. Patients were classified based on the anatomical location of at least two parathyroid glands (intracapsular defined as ≥ 50% of the gland surface in contact with the thyroid capsule). Rates of transient, prolonged, and permanent hypocalcemia and hypoparathyroidism were analyzed. OR with 95% CI were calculated, and p < 0.05 was considered significant. Results: A total of 68 patients were included, with 11.8% having glands in an intracapsular position. Hypocalcemia was more frequent in this group (62.5% vs. 16.7%; OR: 4.4; p = 0.009), as was transient hypoparathyroidism (37.5% vs. 8.3%; OR: 42.7; p < 0.001). No significant differences were observed in prolonged or permanent hypoparathyroidism. Conclusions: Intracapsular location of the parathyroid glands is associated with an increased risk of postoperative hypocalcemia and transient hypoparathyroidism. Prophylactic supplementation should be considered in these patients.