What this study is
This study will test whether 6 months of combination therapy with levothyroxine (LT4) plus liothyronine (LT3) is superior to LT4 plus placebo in participants with hypothyroidism who have residual symptoms of hypothyroidism with TSH levels within the reference range.
What's being tested
- Liothyronine (L-T3)
Intervention · DRUG
Participants will either take LT3 with an LT4 dose that is reduced from baseline or they will take liothyronine placebo with their baseline LT4 dose.
- Levothyroxine Sodium (LT4) Tablets
Intervention · DRUG
All participants will take levothyroxine.
- Liothyronine (LT3) placebo
Intervention · DRUG
Identical placebo tablet without containing liothyronine
Study details
- Sponsor
- University of Pennsylvania
- Conditions
- Hypothyroidism Primary
- Enrolling
- 60 people
- Starts
- 2026-11
- Est. completion
- 2027-11
- Design
- Quadruple-blind, randomized, parallel groups, Phase 2
- Record
- View on ClinicalTrials.gov ↗
Who can join
Age 18 Years – 70 YearsSex ALLHealthy volunteers Not acceptedYou may qualify if
- Male or female, aged 18-70 years
- Hypothyroidism due to either thyroid failure or total thyroidectomy for structural thyroid disease (nodules, benign goiter, or thyroid cancer) for at least 6 months
- Taking 75-150 mcg per day LT4 and a minimum of 1.2 mcg/kg/day, with stable dose of LT4 for at least 3 months prior to enrollment
- TSH of 0.5 to 4.0 mU/L within 2 months of enrollment
- Persistent symptoms for at least 2 months, and a TSQ score of ≥ 5
- For females of reproductive potential: use of highly effective contraception for at least 1 month prior to screening and agreement to use such a method during study participation and for an additional 4 weeks after the end of study intervention.
You can't join if
- Current use of LT3, thyroid extracts, Tirosint liquid or capsules, amiodarone, lithium, methimazole, propylthiouracil, supraphysiologic doses of corticosteroids, immunotherapy, tyrosine kinase inhibitors, interferon, or biotin supplements
- Diseases of the pituitary or hypothalamus
- History of thyroid cancer requiring suppression of TSH secretion
- Unstable cardiac conditions, including uncontrolled hypertension (current blood pressure greater than 160/100), arrhythmia, or angina
- Uncontrolled psychiatric disorders
- Pregnancy or lactation, or planned pregnancy within the next 7 months
- History of food dye allergies
- GFR <30 ml/min/1.73 m2
- Other conditions which, in the opinion of the investigators, would prevent them from participating in the full duration of the study (for example, end-stage cancer)
Sign in and we'll check these against your records.Full criteria on ClinicalTrials.gov ↗
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Study locations (1)
1 openPenn Medicine, Smilow Center for Translational Resarch,
Philadelphia, Pennsylvania, United States
Study team
Sponsor
University of Pennsylvania
Study ID 10094647
Frequently asked questions
The sponsor hasn't published answers to common questions for this trial.