Thyroidectomy with and without laryngectomy: Differences in post-operative hypocalcemia and management

Background: Total laryngectomy (TL) with thyroidectomy can pose significant risks to parathyroid function, and variance in rates of post-operative hypocalcemia (POH) based on extent of thyroidectomy have not been previously reported. Our objective is to identify the rates of hypocalcemia and hypoparathyroidism in TL+/-thyroidectomy and compare this to matched thyroidectomy alone cohorts. Methods: Multi-institutional retrospective chart review of patients treated surgically for laryngeal cancer with TL or benign/malignant thyroid disease with thyroidectomy at regional tertiary care centers in New Orleans and Baton Rouge, Louisiana from 2016 to 2019. Cases were evaluated for post-operative and post-discharge calcium and parathyroid hormone levels, post-operative and long-term calcium supplementation, and intraoperative parathyroid identification and management. Results: 101 TL and 319 thyroidectomy patients' charts were reviewed. Regression analysis revealed increased odds of hypocalcemia and hypoparathyroidism in TL + TT versus TT alone (OR 10.7, OR 16.5, p < 0.001, respectively). TL + HT versus HT alone had increased odds of hypoparathyroidism (OR 1.6, p < 0.001). TL with any thyroidectomy compared to TL alone demonstrated both increased odds of hypocalcemia and hypoparathyroidism (OR 4.4 p = 0.009, and OR 4.5 p = 0.05). Odds of requiring long-term calcium supplementation were significantly increased with the addition of thyroidectomy across all groups. TL + TT was 8 times as likely (p = 0.002) and TL + HT was 5.3 times as likely (p = 0.001) to require long-term calcium supplementation compared to TL alone. Conclusions: Thyroidectomy combined with TL demonstrates marked increased risk of parathyroid dysfunction and resultant POH. Despite improved visualization of soft tissue anatomy with TL, risk of parathyroid injury in these settings requires special attention to extent of parathyroid dissection and potential devascularization to reduce long-term sequelae of hyperparathyroidism. Therefore, post-operative calcium monitoring after TL is necessary and should resemble the long-standing stringent protocols that already exist for monitoring in thyroidectomy populations.