This year at BES we will be debating the controversial topic of Hypothyroidism treatment. Join us on Monday 2 November 2015 at 7pm to hear two leaders in the field discuss the pros and cons of combination T3 and T4 treatments. The debate chair Mark Vanderpump, Consultant Physician and Honorary Senior Lecturer in Diabetes and Endocrinology at the Royal Free London, has written a short blog post to summarise the history of the issue and the key arguments. 

Over one million people in the UK take the thyroid hormone levothyroxine sodium (L-T4). Few are aware of controversies that have surrounded the treatment of hypothyroidism for over a century from the first injections of sheep thyroid by Murray in 1891 to the ongoing debate over the advantages of combining L-T4 with liothyronine (L-T3). The goal of therapy is to restore patient well-being and normalise serum thyrotrophin (TSH) levels. Most patients respond satisfactorily but a minority of treated individuals experience persistent symptoms despite adequate biochemical correction. The care of such individuals is challenging and remains the subject of considerable public interest. Some non-mainstream practitioners advocate the use of alternative thyroid therapies including L-T3 and thyroid extracts, and combination therapy with L-T4 and L-T3.

It can be argued that L-T4 is the most perfect hormone replacement that has yet been devised for endocrine conditions, but there are people who fall outside the current treatment model. Animal-derived products that contain thyroxine (T4) and triiodothyronine (T3) are not physiological and are not the answer in the longer term, but we do need to find ways to ensure that all our patients with hypothyroidism feel the full benefits of replacement therapy.

The British Thyroid Association (BTA) has recently published a peer-reviewed statement in Clinical Endocrinology. Levothyroxine therapy offers a safe, rational, and simplified approach to the correction of hypothyroidism, and for the vast majority of patients, treatment results in improved physical and psychological well-being. The benefits of combination therapy with LT-4 and LT-3 are still unproven and the potential for harm exists with unregulated use of unapproved therapies. Future RCTs will be of value, especially on the use of combination therapy in patients with specified genetic or clinical characteristics. Strategies to improve medication adherence, optimise drug delivery, and standardise thyroid hormone formulations will ultimately improve patient outcomes.