Canadian Endocrinologists' Perspectives on Treatment With Thyroid Hormone Substitutions in Euthyroid and Hypothyroid Patients: A 2023 THESIS Questionnaire Survey.

The practice of treating hypothyroid and euthyroid patients with thyroid hormones varies between countries, as observed in the recent surveys of European thyroid experts, THESIS. As part of the THESIS initiative, we investigated Canadian endocrinologists' perspectives on this topic, focusing on combination therapy with either liothyronine (LT3) plus levothyroxine (LT4) or desiccated thyroid extract (DTE). Members of the Canadian Society of Endocrinology and Metabolism (CSEM) were invited to participate in an anonymous online survey. Out of 348 eligible CSEM members, 68 (19.5%) respondents were included in the analysis. All respondents used LT4 as the first-line treatment for hypothyroid patients. Many respondents (64.7%) would consider LT4 + LT3 for patients on LT4 with persistent symptoms, whereas fewer would consider DTE (16.2%). Most respondents attributed persistent symptoms in LT4-treated patients to psychosocial factors, comorbidities, or unrealistic expectations. Approximately half of the respondents stated that thyroid hormone therapy is never indicated for euthyroid patients. The remaining respondents considered thyroid hormones for euthyroid women with infertility and high thyroid antibody levels (36.8%), depression (13.2%), and growing goiter (7.4%). Following current guidelines, LT4 tablet is the preferred treatment for hypothyroidism. Most respondents would consider triiodothyronine-containing therapy for patients with persistent symptoms, preferring LT4 + LT3 over DTE. The number of endocrinologists considering combination therapy for hypothyroid patients in Canada was higher than in Europe. Finally, at variance with current guidelines, a fraction of the respondents would consider thyroid hormones in patients with non-thyroidal conditions.