Combination T4/T3 trial for hypothyroidism

We are currently seeking participants for our study to help us determine whether taking an extra thyroid hormone (T3) as well as thyroxine (T4) helps reduce symptoms hypothyroidism.

About our study

Hypothyroidism (underactive thyroid) is a very common condition. The standard treatment is thyroxine (T4). However, about 10% of people who take T4 continue to have symptoms that might be due to hypothyroidism and are dissatisfied with their treatment. There are a number of reasons to think that this might because levels of the most active thyroid hormone, T3, are too low, but simply increasing the T4 dose might actually make the situation worse.

It is possible that using combination T4/T3 might be better for some people with hypothyroidism, particularly if they have ongoing symptoms despite taking T4 regularly and having thyroid function tests that lie in the normal range.

We plan to study whether combination T4/T3 is better than T4 by itself for individuals who are dissatisfied with T4 alone. If combination T4/T3 treatment improves symptoms of hypothyroidism better than standard T4 treatment, this would become the new standard treatment. On the other hand, if combination treatment is not better than standard treatment, we could conclude this definitively meaning that clinicians and patients would know that this treatment is ineffective, and that patients would not benefit from taking it.

What's involved

The study lasts one year. For four periods of eight weeks, participants will take either combination T4/T3 treatment or T4 treatment with an inactive (placebo) treatment. The decision as to which treatment will be made randomly (i.e. by chance).

For the remainder of the study, participants will take their usual daily dose of T4. During the study, participants will need to have regular blood tests (approximately every 2-4 weeks) and fill in questionnaires every 2 weeks about quality of life. Every 1-2 months there is an in-person visit at the University of Auckland Medical school, where further questionnaires will be completed.

Eligibility criteria

We are looking for participants who are:

  • 18 years and over
  • Have confirmed hypothyroidism
  • Are receiving treatment for hypothyroidism but still have persistent symptoms for more than 6 months.
  • Have taken T4 for at least 6 months, with normal thyroid function blood tests for at least 3 months and had been on stable T4 dose for at least the preceding 3 months.

Participants must also have at least moderate level symptoms of at least two of the following:

  • Tiredness, fatigue or lethargy
  • Difficulty in concentrating or thinking
  • Poor memory or "brain fog"
  • Mood disturbance
  • Bloating or difficulty maintaining weight

Contact details

Shirley Ward

Phone: (09) 923 1482   

Further information

This study was approved by the Southern Health and Disability Ethics Committee (21/STH/221).