Higher Post-Operative L-Thyroxine Dosage Needed After Right Compared to Left-Lobe Hemithyroidectomy.

PURPOSE: Usually, the right lobe of the thyroid gland is larger than the left lobe. Post hemithyroidectomy, the remaining lobe grows by up to 30% as compensation. Thyroxine replacement is still necessary for 22%-60% of all patients. We aimed at investigating whether a right-lobe hemithyroidectomy requires higher postoperative levothyroxine dosages. PATIENTS AND METHODS: 426 adult patients who received a hemithyroidectomy and a follow-up visit (median 9 months post-surgery) at the Medical University of Vienna between 1994 and 2018 were identified and investigated in this retrospective study with a weight and pre-surgery TSH-adjusted model. RESULTS: Patients required a higher mean levothyroxine dosage after right-lobe hemithyroidectomy (mean = 68.1 μg/day, p = 0.018) compared to the left lobe (mean = 60.2 μg/day). CONCLUSION: Patients require roughly 13% more levothyroxine substitution after hemithyroidectomy of the right lobe compared to the left lobe, which should be considered in post-op care.