Morbidity And Mortality In Liothyronine Treated Patients: LT3 Outcome Study

Professor Colin Dayan, MA FRCP PhD, Professor of Clinical Diabetes and Metabolism, Cardiff University


Thyroxine is the usual treatment for people with an underactive thyroid problem. Most patients who take thyroxine feel well on this. However a small proportion of patients do not feel well on thyroxine alone and some practitioners treat such patients with another drug called T3. Whether T3 works just as well as thyroxine remains to be proven and opinions are divided on this. However, a growing number of patients are prescribed T3, mostly from unregulated or independent medical practices. This is worrying because the long term safety of T3 has not been established and current guidelines written by medical professionals do not advocate its routine use in practice.

The current study proposes to investigate whether patients who receive T3 (liothyronine) have a greater long term risk of heart problems, strokes, and death when compared to those who are treated in the standard way with thyroxine.

We plan to carry out this investigation using data from the private clinic records of the late Dr Gordon Skinner comprising the details of over 3,000 patients treated over a period of 20 years. Since Dr Skinner’s death, the Vaccine Research Trust that he established has been the Custodian of the clinic data. Via the Vaccine Research Trust the data from these patients will be linked anonymously to information held in the NHS Health and Social Care Information Centre (HSCIC) regarding hospital admissions from heart disease and strokes as well as information on death. We will then compare this data to similar data in individuals that have only received LT4. We will be able to do this without knowing the identities of any of these patients or any identifiable health records going outside of the Vaccine Research Trust. On this basis, individual patient consent is not required. However, patients can opt-out from having their anonymised data included in the study

Patient opt-out notice

Our study will be of importance to patients with thyroid disease. An increasing number of patients are asking for a trial of T3 or NDT therapy and attending private clinics, but the risks to patients of heart disease, strokes, and death with of this practice are unknown. If there is a significantly increased risk, as many endocrinologists suspect, then patients need to be made aware of the facts. On the other hand if the risk is not different from patients taking LT4 then it will allow us to undertake further trials to try and understand if LT3 could benefit patients with an underactive thyroid problem.

Please read progress report

Final report to follow.