BACKGROUND To assess the impact of total thyroidectomy on thyroid function. METHODS Monocentric observational prospective study. Patients who benefited from a total thyroidectomy in the Department of Otolaryngology-Head and Neck Surgery between September 2017 and July 2019 were included. Three blood samples were taken from each patient during the perioperative period: preoperatively (T0), intraoperatively (T1), and postoperatively (T2). Changes in TSH, T4, T3, and thyroglobulin levels were evaluated from T0 to T2. Epidemiological data were retrieved from the medical charts. Statistical analyses were performed for the entire cohort and subgroups regarding preoperative treatment and type of disease. RESULTS Seventy-seven patients were included in the study. T4 and thyroglobulin levels increased significantly from T0 to T1. TSH, T4, T3, and thyroglobulin levels decreased significantly from T1 to T2. CONCLUSIONS Our study confirmed the hypothesis of variable kinetics of thyroid hormone levels associated with the manipulation of the thyroid gland during surgery, but none of these changes resulted in clinical effects, including thyrotoxicosis.