Comparison Among the Daily Levothyroxine Doses According to the Etiology of Hypothyroidism

Abstract

Background: The initial doses of levothyroxine (LT4) replacement therapy in patients with hypothyroidism in clinical practice are usually empirical, perhaps because of the lack of data suggesting how much hormone is needed in each patients situation. The aim of our study is to evaluate the daily dose of oral LT4 needed to achieve the TSH goals in patients with hypothyroidism caused by different etiologies.

Methods: Patients were divided and analyzed according to the etiology of the hypothyroidism. We retrospectively evaluated data from 557 patients (501 women) with hypothyroidism who had normal serum TSH and free T4 (FT4) levels in at least two consecutive appointments in which they were using the same levothyroxine doses.

Results: The mean dose of levothyroxine in the total sample was 91.3 37.18 g/day (1.39 0.63 g/kg/day). Stratifying by group: central hypothyroidism 53.94 28.07 g/day (0.82 0.48 g/kg/day); primary hypothyroidism (no intervention) 81.37 29.84 g/day (1.25 0.53 g/kg-day); post radioactive iodine (I¹³¹) 97.42 28.32 g/day (1.33 0.55 g/kg/day); post-thyroidectomy for benign causes 102.8 36.96 g/day (1.54 0.59 g/kg/day); post-thyroidectomy for thyroid cancer 138.5 35.25 g/day (2.17 0.58 g/kg/day).

Conclusion: The dose of LT4 required to stabilize the patient varies according to different hypothyroidism etiologies.




J Endocrinol Metab. 2013;3(1-2):1-6
doi: https://doi.org/10.4021/jem165w