The outcomes of levothyroxine therapy and thyroid hormone after thyroidectomy: A retrospective study

Background: Optimal pharmacotherapy and maintenance of thyroid hormone homeostasis following thyroidectomy are essential for effective metabolic regulation and overall endocrine balance. Surgical techniques that preserve neural integrity play a critical role in maintaining endocrine balance and ensuring stability of thyroid hormone dosage, thereby influencing the overall success of thyroid hormone replacement therapy. Objective: This study assessed the impact of intraoperative nerve monitoring (IONM) during thyroidectomy on postoperative endocrine outcomes, with prominence on thyroid hormone stability and levothyroxine dose requirements. Methods: The study includes review of 45 patients who underwent thyroid surgery from 2018 to 2023 at a tertiary care center in Turkey. The patients were subsequently allocated into two groups: The first group underwent surgery with IONM (n = 23), whereas the second group underwent surgery without IONM (n = 22). The primary outcome was levothyroxine dose stability, defined as achievement of euthyroid status (TSH 0.4–4.0 mIU/L with normal FT4 levels) without further dose adjustment over two consecutive follow-up visits. Secondary outcomes included time to euthyroid status, number of dose adjustments, postoperative hypocalcemia, RLN injury and hospital stay duration. Postoperative thyroid function tests were assessed at 2, 6 and 12 weeks. Statistical analysis was conducted using SPSS Statistics version 26.0. Result: Patients undergoing thyroid surgery with IONM had an average hospital stay of 1.67 days, while those who did not have IONM had an average hospital stay of 1.77 days. No statistically significant difference between the two groups regarding total time in the operating room. Patients in the IONM group demonstrated a more stable pattern of postoperative thyroid hormone levels and a lower rate of endocrine-related complications compared to the non-IONM group. Conclusion: This study suggests that IONM was associated with postoperative hormonal stability as well as more predictable pharmacotherapy with respect to levothyroxine use. Given the retrospective design, these findings demonstrate association rather than causation and further prospective studies are required.