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Trial Lecture – time and place
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Adjudication committee
- First opponent: Professor Ulla Feldt-Rasmussen, Rigshospitalet, Copenhagen University Hospital, Denmark
- Second opponent: Professor Ragnar Martin Joakimsen, UiT - Arctic University of Norway
- Third member and chair of the evaluation committee: Associate Professor Mona-Elisabeth Rootwelt-Revheim, University of Oslo
Chair of the Defence
Associate Professor Per Medbøe Thorsby, University of Oslo
Principal Supervisor
Professor Emeritus Erik Fink Eriksen, University of Oslo
Summary
A significant proportion of patients with hypothyroidism complain of persistent symptoms of thyroid hormone deficiency despite optimal standard therapy with T4 hormone. Adequate treatment of this group of patients is still a subject to debate.
The aim of this study was therefore to compare the effect of T4 hormone therapy with T3 hormone therapy in female hypothyroid patients with persistent hypothyroid symptoms despite previously T4 hormone treatment with normal TSH levels for at least 6 months. Using a crossover design, participants received both hormones for 12 weeks each in a random order.
After both treatment periods, we investigated effects on several different outcomes including quality of life, thermogenesis and objective biological markers of thyroid hormone action, as well as adverse effects on the heart and skeleton.
We found that treatment with T3 hormone led to higher body temperature and lower weight. Indirectly, using infrared thermal imaging, we found that reduced dermal heat loss combined with increased activation of heat-producing brown adipose tissue, may explain the observed change in both body temperature and weight on treatment with T3 hormone. Furthermore, patients on T3 hormone, with median TSH values well within the normal range, scored higher on three different quality of life questionnaires, without concomitant adverse effects on the heart or skeleton. We also found lower levels of the inactivate form of thyroid hormone (reverse T3), in addition to a more favorable lipid profile after 12 weeks of treatment with T3 hormone compared to T4 hormone.
The findings in this study therefore suggest that treatment with T3 hormone may improve health in patients with hypothyroidism, who experience persistent symptoms of thyroid hormone deficiency on T4 substitution.
Additional information
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