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Levothyroxine

Clinical trials investigating Levothyroxine are studying how it may help in different patient groups, including children receiving radiation, adults with subclinical hypothyroidism, and patients after thyroid surgery. These studies look at outcomes such as hypothyroidism prevention, sexual function, and kidney function. Most trials are Phase 3 and focus on whether treatment works and how well it is measured over time.

Table of Contents

Clinical trial overview

The trial data show three interventional studies of Levothyroxine, and all are in Phase 3.[1][2][3] Phase 3 studies usually test treatment effects in larger groups and measure results carefully over time.[1][2][3]

These trials study very different situations: prevention of thyroid problems after radiation, effects on sexual function in subclinical hypothyroidism, and kidney function after thyroid surgery.[1][2][3] The enrolled groups are small to moderate in size, with 65, 90, and 56 participants planned or included in the listed studies.[1][2][3]

Radiation-related hypothyroidism prevention

One authorised Phase 3 trial, called WINHYPO 2021, studies children and young people with medulloblastoma and patients with Hodgkin or non-Hodgkin lymphoma who need radiation therapy near the thyroid area.[1] The study asks whether adding Levothyroxine during radiotherapy can protect the thyroid and reduce later hypothyroidism.[1]

The brief summary says the goal is to reduce the incidence of hypothyroidism after radiation by using TSH suppression during irradiation.[1] TSH suppression means lowering TSH levels, which are measured in blood and used to check thyroid function.[1]

The main endpoint is hypothyroidism-free survival at 3 years after radiotherapy, in patients whose thyroid tissue is partly or fully included in the radiation field.[1] The analysis uses the intention-to-treat population, and patients are followed with TSH blood tests to see whether hypothyroidism appears within 3 years from the start of radiotherapy.[1]

Levothyroxine and sexual function in subclinical hypothyroidism

Another Phase 3 trial, which is completed, studied adults with subclinical hypothyroidism and erectile dysfunction.[2] The brief summary says the researchers wanted to assess the impact of Levothyroxine treatment on sexual activity in patients with TSH greater than 5, adjusted for body weight and baseline TSH values.[2]

This study also included sildenafil as a comparison treatment in the listed interventions, but the trial data focus on how Levothyroxine was used in the study design.[2] The target population was patients with thyroid underactivity that was mild or not fully obvious, together with erectile dysfunction.[2]

The study measured changes in several questionnaires over time, including IIEF-15, EHS, PGIC, and EDITS, from baseline to 3 months after treatment.[2] These tools help show how patients feel about erectile function, erection firmness, satisfaction with treatment, and overall change.[2]

Early thyroid hormone replacement after hemithyroidectomy

A third authorised Phase 3 randomised controlled trial studies patients at risk of postoperative hypothyroidism after hemithyroidectomy, which means removal of one half of the thyroid gland.[3] The study also includes patients with incident kidney dysfunction and chronic kidney disease in the listed conditions.[3]

Researchers want to know whether postoperative treatment with Levothyroxine improves kidney function compared with standard care without Levothyroxine.[3] The brief summary says the key question is whether early thyroid hormone replacement leads to better kidney function 3 months after surgery.[3]

The primary outcome is the change in eGFR from baseline to 3 months after surgery, measured with standard laboratory methods.[3] eGFR is a standard way to estimate how well the kidneys are filtering blood.[3]

Main outcomes and how they are measured

The radiation study uses a time-based outcome, looking at whether patients stay free from hypothyroidism for 3 years after radiotherapy.[1] It also uses TSH blood testing to check when hypothyroidism begins.[1]

The sexual function study uses patient-reported questionnaires, which means the patients answer questions about symptoms and treatment effects themselves.[2] The listed tools measure erectile function, erection hardness, treatment satisfaction, and the patient’s own impression of change.[2]

The kidney study uses a laboratory outcome, eGFR, to track change in kidney function over 3 months.[3] This gives a clear number that can be compared before and after surgery.[3]

Who may be included in these studies

The first study is for patients with medulloblastoma at any stage and any biological risk, plus pediatric patients with Hodgkin or non-Hodgkin lymphoma who need radiation on the thyroid site.[1] This means the trial is focused on children and young people whose cancer treatment may affect the thyroid.[1]

The second study includes patients with subclinical hypothyroidism and erectile dysfunction, with TSH greater than 5 mentioned in the brief summary.[2] The trial is aimed at adults who have both a mild thyroid problem and sexual function symptoms.[2]

The third study includes patients at risk of hypothyroidism after hemithyroidectomy and looks at kidney-related outcomes after surgery.[3] The trial also lists chronic kidney disease and incident kidney dysfunction among the conditions studied.[3]

Trial ID Phase Condition studied Status Enrollment
2024-512642-42-00 Phase 3 Hodgkin and non-Hodgkin lymphoma, medulloblastoma; prevention of radiation-related hypothyroidism Authorised 65
2024-514789-38-00 Phase 3 Subclinical hypothyroidism and erectile function Completed 90
2025-524175-23-00 Phase 3 Hypothyroidism risk after hemithyroidectomy; kidney function and quality of life Authorised 56

FAQ

  • What are clinical trials with Levothyroxine trying to find out? These trials are testing whether Levothyroxine can prevent hypothyroidism after radiation, improve sexual function in people with subclinical hypothyroidism, and support kidney function after hemithyroidectomy. They also measure how patients change over time using blood tests and questionnaires.
  • Who can take part in these studies? The studies include children with medulloblastoma or lymphoma who need radiation near the thyroid, adults with subclinical hypothyroidism and erectile dysfunction, and patients at risk of hypothyroidism after hemithyroidectomy. Each trial has its own entry rules.
  • What phases are the Levothyroxine trials in? The trials listed are all Phase 3 studies. Phase 3 means the treatment is being tested in larger groups to see how well it works and to measure outcomes carefully.
  • What conditions are being studied? The trials study hypothyroidism, medulloblastoma, Hodgkin and non-Hodgkin lymphoma, erectile dysfunction, subclinical hypothyroidism, chronic kidney disease, and incident kidney dysfunction. Some trials focus on preventing a problem, while others look at recovery after treatment.
  • What results are the researchers measuring? The main results include hypothyroidism-free survival, changes in TSH blood levels, questionnaire scores about erectile function and treatment satisfaction, and change in eGFR, which is a kidney function measure. These results help show whether the study treatment is making a difference.

Ongoing Clinical Trials on Levothyroxine

  • Effect of levothyroxine on kidney function in patients at risk of hypothyroidism after partial thyroid surgery

    Recruiting

    1 1 1 1
    Investigated diseases:
    Investigated drugs:
    Denmark

  • Study on Preventing Hypothyroidism in Patients with Medulloblastoma and Pediatric Lymphoma Using Levothyroxine During Radiation Therapy

    Recruiting

    1 1 1 1
    Investigated diseases:
    Investigated drugs:
    Italy

  • Study on Levothyroxine and Sildenafil for Improving Erectile Function in Patients with Subclinical Hypothyroidism and Erectile Dysfunction

    Not recruiting

    1 1 1 1
    Investigated diseases:
    Investigated drugs:
    Spain

Glossary

  • Hypothyroidism: A condition where the thyroid gland does not make enough thyroid hormone. In these trials, it is often something the researchers are trying to prevent or detect early.
  • Subclinical hypothyroidism: A mild form of thyroid underactivity. Blood tests can look abnormal, but symptoms may be mild or not obvious.
  • Radiotherapy: Treatment that uses radiation to kill cancer cells. In one trial, researchers are studying whether thyroid problems can be reduced during radiation near the thyroid.
  • TSH: Thyroid-stimulating hormone. This is a blood test used to check how the thyroid is working and to look for hypothyroidism.
  • Hypothyroidism-free survival: The length of time a person stays free from hypothyroidism. This is the main outcome in the radiation protection trial.
  • Intention-to-treat population: A group that includes all patients assigned to a study group, even if they do not complete treatment exactly as planned. This helps keep the results fair.
  • IIEF-15: A questionnaire used to measure erectile function. It asks about different parts of sexual function.
  • EHS: Erectile Hardness Score. This measures how firm an erection is.
  • EDITS: Erectile Dysfunction Inventory of Treatment Satisfaction. This questionnaire asks how satisfied a patient is with treatment.
  • PGIC: Patient Global Impression of Change. This is a patient-reported score showing how much the person feels better or worse after treatment.
  • eGFR: Estimated glomerular filtration rate. This is a standard measure of kidney function.
  • Hemithyroidectomy: Surgery to remove one half of the thyroid gland. One trial studies people at risk of hypothyroidism after this surgery.

References

  1. https://clinicaltrials.gov/study/2024-512642-42-00
  2. https://clinicaltrials.gov/study/2024-514789-38-00
  3. https://clinicaltrials.gov/study/2025-524175-23-00