Comparing LT4LT3 Combination Therapy to LT4 Alone for Adults with Autoimmune Hypothyroidism and Persistent Tiredness

What this Trial Is About

Researchers are investigating the effectiveness of adding liothyronine LT3 to levothyroxine LT4 treatment in patients with autoimmune hypothyroidism who continue to experience severe tiredness despite having normalized thyroid hormone levels on LT4 alone. This study addresses the problem that LT4 monotherapy may not fully replicate the natural balance of thyroid hormones, as healthy individuals produce some T3 directly. The trial also explores whether certain genetic factors influence response to combination therapy. The study begins with a run-in period where all participants switch to a standardized generic LT4 to stabilize thyroid hormone levels. After confirming normal TSH levels and persistent tiredness, participants enter a one-year randomized, double-blind trial comparing LT4LT3 combination therapy to LT4 with placebo. The LT4LT3 group takes LT4 once daily and LT3 twice daily at a set ratio. Visits occur at baseline and multiple times over the year to adjust doses and monitor health. Participants undergo physical exams, ECGs, blood tests, and complete questionnaires about tiredness, quality of life, and medical resource use throughout the study. Additional measures include bone markers, scans, cardiovascular and metabolic assessments, and neurocognitive tests in subgroups. The main outcome is the change in tiredness scores over 52 weeks, with safety and genetic factors also evaluated. The total study duration includes the run-in and treatment phases, lasting several months to over a year.

LT4/LT3 Combination Therapy Versus LT4 Monotherapy in Patients with Autoimmune Hypothyroidism.