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Study on Levothyroxine and Liothyronine for Patients with Autoimmune Hypothyroidism and Persistent Tiredness

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial is focused on studying the effects of a combination therapy for patients with autoimmune hypothyroidism, a condition where the thyroid gland does not produce enough hormones, leading to symptoms like tiredness. The study will compare the effects of a combination of two medications, levothyroxine and liothyronine, against the use of levothyroxine alone. Levothyroxine is a synthetic form of the thyroid hormone thyroxine, while liothyronine is a synthetic form of the hormone triiodothyronine. The trial will also include a group receiving a placebo, which looks like the medication but contains no active ingredients.

The purpose of the study is to investigate whether the combination of levothyroxine and liothyronine can reduce tiredness more effectively than levothyroxine alone in patients who continue to feel tired despite treatment. The study will last for one year, during which participants will receive either the combination therapy, levothyroxine alone, or a placebo. Researchers will monitor changes in tiredness and other thyroid-related symptoms, as well as overall quality of life. The study will also explore if certain genetic variations in participants affect the treatment outcomes.

Participants will be asked to take the medication orally and will have regular check-ups to assess their symptoms and any side effects. The trial aims to provide insights into whether the combination therapy offers a better treatment option for those with persistent symptoms of autoimmune hypothyroidism. The findings could help improve treatment strategies and enhance the quality of life for patients with this condition.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial assessment

    Upon joining the study, an initial assessment will be conducted to confirm eligibility. This includes reviewing your medical history and current health status.

    You will be asked to provide information about your experience with hypothyroidism and any persisting tiredness or other complaints.

  2. Step 2

    Randomization

    You will be randomly assigned to one of two groups: one receiving levothyroxine (LT4) alone or a combination of levothyroxine (LT4) and liothyronine (LT3).

    This process ensures that the study results are unbiased and reliable.

  3. Step 3

    Medication administration

    If assigned to the LT4 group, you will continue your current LT4 dosage, which ranges from 75 to 225 micrograms per day, based on your previous treatment.

    If assigned to the LT4/LT3 combination group, you will receive a combination of LT4 and LT3. The specific dosages will be determined by the study team.

    The medication will be taken orally, as tablets, once daily for the duration of the study.

  4. Step 4

    Regular follow-ups

    Throughout the study, regular follow-up appointments will be scheduled to monitor your health and response to the treatment.

    These appointments will include physical examinations, blood tests, and questionnaires to assess your quality of life and any changes in symptoms.

  5. Step 5

    Completion of study

    The study will last for 52 weeks, after which a final assessment will be conducted.

    This assessment will evaluate the overall effects of the treatment on your tiredness and other symptoms related to hypothyroidism.

Who can join the trial?

7 criteria

  • Patients must be 18 years or older.
  • Patients must have either overt (clear symptoms) or subclinical hypothyroidism (mild or no symptoms but abnormal blood test results).
  • Patients must have been on LT4 monotherapy (a treatment with a thyroid hormone called levothyroxine) for at least 6 months.
  • The dose of LT4 must be between 75-225 micrograms, with at least 1.2 micrograms per kilogram of body weight.
  • TSH levels (a hormone that stimulates the thyroid) must be within the normal range for at least 3 months.
  • Patients must experience severe tiredness that significantly affects daily life for at least 6 months, with or without other ongoing complaints. This is based on the patient's own experience.
  • Patients must be able to speak and read Dutch fluently.

Who cannot join the trial?

4 criteria

  • Patients who do not have **autoimmune hypothyroidism**. This is a condition where the immune system attacks the thyroid gland, leading to low thyroid hormone levels.
  • Patients who are not experiencing **persisting tiredness** despite being treated with **LT4 monotherapy**. LT4 is a medication used to treat low thyroid hormone levels.
  • Patients who are not within the specified age range for the study.
  • Patients who are part of a vulnerable population, which means they might need special protection or care.
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Investigated drugs

  • LT4

    is a medication used to treat people with an underactive thyroid, a condition known as hypothyroidism. It is a synthetic form of a hormone that the thyroid gland normally produces. This hormone helps regulate the body's energy and metabolism. In this trial, LT4 is used to see if it can help reduce tiredness in patients with autoimmune hypothyroidism.

  • LT3

    is another medication used in the treatment of hypothyroidism. Like LT4, it is a synthetic form of a thyroid hormone, but it is a different type of hormone. LT3 works more quickly in the body compared to LT4. In this trial, LT3 is combined with LT4 to see if this combination can better reduce tiredness in patients with autoimmune hypothyroidism compared to using LT4 alone.

What is already known about the treatment

  • Levothyroxine (LT4)

    Levothyroxine is administered orally in the form of tablets and is commonly used to treat hypothyroidism, a condition where the thyroid gland does not produce enough hormones. It is well-established in medical practice and literature as a standard treatment for this condition. The main therapeutic indication is to replace or supplement the thyroid hormone in patients with an underactive thyroid. At the molecular level, levothyroxine works by being converted into triiodothyronine (T3) in the body, which then enters cells and influences the metabolism and energy production. It is classified as a thyroid hormone replacement therapy.

  • Liothyronine (LT3)

    Liothyronine is also administered orally in tablet form and is used in combination with levothyroxine to treat hypothyroidism, particularly in patients who continue to experience symptoms despite standard treatment. This combination therapy is currently being studied in clinical trials to assess its effectiveness in improving quality of life for these patients. Liothyronine acts directly as the active thyroid hormone T3, which regulates metabolism and energy levels at the cellular level. It is classified as a thyroid hormone replacement therapy.

Investigated diseases

Hypothyroidism – Hypothyroidism is a condition where the thyroid gland does not produce enough thyroid hormones. This deficiency leads to a slowing down of the body's metabolism. Symptoms often include fatigue, weight gain, and sensitivity to cold. As the condition progresses, individuals may experience dry skin, hair loss, and muscle weakness. If left untreated, it can lead to more severe symptoms such as depression and impaired memory. The progression of symptoms can vary widely among individuals.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2024-513883-24-00Estimated enrolment600 patientsSponsorErasmus Universitair Medisch Centrum Rotterdam (Erasmus MC)

sourced from the EU Clinical Trials Register and site verification

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