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

All Canadian endocrinologist respondents used LT4 as the first-line treatment for hypothyroid patients.

• Survey included 68 respondents out of 348 eligible CSEM members (19.5% response rate).
• Respondents were members of the Canadian Society of Endocrinology and Metabolism (CSEM).
• The survey was conducted as an anonymous online questionnaire in 2023 as part of the THESIS initiative.

A majority of Canadian endocrinologists (64.7%) would consider LT4+LT3 combination therapy for patients on LT4 with persistent symptoms.

• 64.7% of respondents would consider LT4+LT3 combination therapy for persistent symptoms in LT4-treated patients.
• Only 16.2% of respondents would consider desiccated thyroid extract (DTE) for the same indication.
• The number of Canadian endocrinologists considering combination therapy was described as higher than in Europe.

Most Canadian endocrinologists attributed persistent symptoms in LT4-treated patients to psychosocial factors, comorbidities, or unrealistic expectations.

• This attribution was the predominant explanation given by respondents for persistent symptoms despite LT4 therapy.
• This finding was noted among respondents who nonetheless might still consider combination therapy.

Approximately half of the respondents stated that thyroid hormone therapy is never indicated for euthyroid patients.

• The remaining respondents considered thyroid hormones for euthyroid patients in select circumstances.
• 36.8% of respondents would consider thyroid hormones for euthyroid women with infertility and high thyroid antibody levels.
• 13.2% would consider thyroid hormones for euthyroid patients with depression.
• 7.4% would consider thyroid hormones for euthyroid patients with a growing goiter.

Canadian endocrinologists' consideration of combination triiodothyronine-containing therapy for hypothyroid patients was higher than rates observed in European surveys.

• The THESIS initiative previously surveyed European thyroid experts, providing a comparative dataset.
• The paper states 'the number of endocrinologists considering combination therapy for hypothyroid patients in Canada was higher than in Europe.'
• Both LT4+LT3 and DTE were assessed as triiodothyronine-containing options, with LT4+LT3 preferred over DTE.

A fraction of Canadian endocrinologist respondents would consider thyroid hormones in patients with non-thyroidal conditions, at variance with current guidelines.

• Current guidelines do not support thyroid hormone therapy for euthyroid patients.
• Non-thyroidal indications considered included infertility with high antibodies (36.8%), depression (13.2%), and growing goiter (7.4%).
• The paper explicitly notes this practice is 'at variance with current guidelines.'