Use of liothyronine (T3) in hypothyroidism: Joint British Thyroid Association/Society for endocrinology consensus statement

EMAS position statement: Thyroid disease and menopause

INTRODUCTION

Thyroid diseases are common in women in their late reproductive years; therefore, thyroid disease and menopause may co-exist. Both conditions may present with a wide range of symptoms, leading to diagnostic challenges and delayed diagnosis. Aim To construct the first European Menopause and Andropause Society (EMAS) statement on thyroid diseases and menopause.

MATERIALS AND METHODS

Literature review and consensus of expert opinion (EMAS executive board members/experts on menopause and thyroid disease).

SUMMARY RECOMMENDATIONS

This position paper highlights the diagnostic and therapeutic dilemmas in managing women with thyroid disease during the menopausal transition, aiming to increase healthcare professionals' awareness of thyroid disorders and menopause-related symptoms. Clinical decisions regarding the treatment of both conditions should be made with caution and attention to the specific characteristics of this age group while adopting a personalized patient approach. The latter must include the family history, involvement of the woman in the decision-making, and respect for her preferences, to achieve overall well-being.

Liothyronine (LT3) prescribing in England: Are cost constraints inhibiting guideline implementation?

BACKGROUND

Primary hypothyroidism affects about 3% of the general population in Europe. In most cases people with hypothyroidism are treated with levothyroxine. In the context of the 2023 British Thyroid Association guidance and the 2020 Competitions and Marketing Authority (CMA) ruling, we examined prescribing data for levothyroxine, Natural desiccated thyroid (NDT) and liothyronine by dose, regarding changes over the years 2016-2022.

DESIGN

Monthly primary care prescribing data for each British National Formulary code were analysed for levothyroxine, liothyronine and NDT.

PATIENTS AND MEASUREMENTS

The rolling 12-month total/average of cost or prescribing volume was used to identify the moment of change. Results included number of prescriptions, the actual costs, and the cost/prescription/mcg of drug.

RESULTS

Liothyronine: In 2016 94% of the total 74,500 prescriptions were of the 20 mcg dose. In 2020 the percentage prescribed in the 5 mcg and 10 mcg doses started to increase so that by 2022 each reached nearly 27% of total liothyronine prescribing. The average cost/prescription in 2016 of 20 mcg was £404/prescription and this fell by 80% to £101 in 2022; while the 10 mcg cost of £348/prescription fell by only 35% to £255 and the 5 mcg cost of £355/prescription fell by 38% to £242/prescription. The total prescriptions of liothyronine in 2016 were 74,605, falling by 30% up to 2019 when they started to grow again - most recently at 60,990-15% lower than the 2016 figure, with the result that total costs fell by 70% to £9 m/year.

CONCLUSIONS

Liothyronine costs fell after the CMA ruling but remain orders of magnitude higher than for levothyroxine. The remaining 0.2% of patients with liothyronine treated hypothyroidism are still absorbing 16% of medication costs. The lower liothyronine 5cmg and 10 mcg doses as recommended by BTA are 240% the costs of the 20 mcg dose. Thus, following latest BTA guidance which recommends the lower liothyronine doses still incurs substantial additional costs vs the prescribing liothyronine in the no longer recommended treatment regime. High drug price continues to impact clinical decisions, potentially limiting liothyronine therapy availability to a considerable number of patients who could benefit from this treatment.

Use of thyroid hormones in hypothyroid and euthyroid patients: A survey of members of the Endocrine Society of Australia

OBJECTIVE

Hypothyroidism is a common endocrine condition usually managed with levothyroxine (LT4). However, controversy remains around the use of liothyronine (LT3). We aimed to investigate the practices of Australian endocrinologists when managing patients with hypothyroidism, their use of LT3 + LT4 combination therapy and use of thyroid hormones in euthyroid patients.

DESIGN AND PARTICIPANTS

Members of the Endocrine Society of Australia (ESA) were invited to participate in an online questionnaire.

MEASUREMENTS

We analysed questionnaires that had complete demographic data.

RESULTS

Eighty-seven questionnaires fulfilled the criteria. LT4 was used as first line treatment for hypothyroidism by all respondents. Only 45% reported that their patients were dispensed the brand of LT4 that they recommend. LT3 (alone or in combination) was prescribed by 44% in their clinical practice. Although 49% of respondents would consider LT3 + LT4 in patients with normal TSH who had ongoing symptoms of hypothyroidism, the inability of LT4 to restore normal physiology was ranked the least likely explanation for persistent symptoms and only 32% would consider it for themselves if they were diagnosed with hypothyroidism. The majority (55%), in accordance with evidence, would not prescribe thyroid hormone to euthyroid individuals but 39% would consider use in euthyroid female infertility with high levels of thyroid antibodies and 11% in euthyroid patients with a simple goitre growing over time. LT4 use in pregnancy was variable among members.

CONCLUSIONS

Australian endocrinologists mostly follow international guidelines when prescribing thyroid hormone therapy and many prescribe combination LT3 and LT4 therapy, particularly for patients who remain symptomatic on LT4 monotherapy. Prescribing practices are largely similar to other countries who have completed similar questionnaires.

Emerging Therapies in Hypothyroidism

Levothyroxine (LT4) is effective for most patients with hypothyroidism. However, a minority of the patients remain symptomatic despite the normalization of serum thyrotropin levels. Randomized clinical trials including all types of patients with hypothyroidism revealed that combination levothyroxine and liothyronine (LT4+LT3) therapy is safe and is the preferred choice of patients versus LT4 alone. Many patients who do not fully benefit from LT4 experience improved quality of life and cognition after switching to LT4+LT3. For these patients, new slow-release LT3 formulations that provide stable serum T3 levels are being tested. In addition, progress in regenerative technology has led to the development of human thyroid organoids that restore euthyroidism after being transplanted into hypothyroid mice. Finally, there is a new understanding that, under certain conditions, T3 signaling may be compromised in a tissue-specific fashion while systemic thyroid function is preserved. This is seen, for example, in patients with metabolic (dysfunction)-associated fatty liver disease, for whom liver-selective T3-like molecules have been utilized successfully in clinical trials.

Designing a combined liothyronine (LT3), L- thyroxine (LT4) trial in symptomatic hypothyroid subjects on LT4 - the importance of patient selection, choice of LT3 and trial design

Approximately 10%-15% of subjects with hypothyroidism on L-thyroxine (LT4) alone have persistent symptoms affecting their quality of life (QoL). Although the cause is unclear, there is evidence that "tissue T3 lack" may be responsible. If so, combining liothyronine (LT3) with LT4 would be helpful. However, randomized controlled trials (RCT), have not established greater efficacy for the LT3 + LT4 combination in these subjects than for LT4 alone. While the trial design may have been responsible, the use of unphysiological, short-acting LT3 preparations and non-thyroid-specific patient-reported outcome measures (PROMs) may have contributed. We recommend attention to the following aspects of trial design for future RCTs of LT3 + LT4 compared to LT4 alone: (a) Subject selection-(i) measurable symptoms (disadvantages should be recognized); (ii) using a validated thyroid specific PROM such as ThyPRO39 or the Composite scale derived from it; (iii) those taking over 1.2 μg/day or 100 μg/day (for pragmatic reasons) of LT4 defining a population likely without intrinsic thyroid activity who depend on exogenous LT4; (iv) recruiting a preponderance of subjects with autoimmune thyroiditis increasing generalisability; and (v) those with a high symptom load with a greater response to combination therapy e.g. those with the deiodinase 2 polymorphism. (b) The use of physiological LT3 preparations producing pharmacokinetic similarities to T3 profiles in unaffected subjects: two long-acting LT3 preparations are currently available and must be tested in phase 2b/3 RCTs. (c) The superiority of a crossover design in limiting numbers and costs while maintaining statistical power and ensuring that all subjects experienced the investigative medication.

Myxedema Coma Precipitated by Sepsis in a Patient With a Complex Mental Health History

Myxedema coma is a rare and life-threatening manifestation of severe hypothyroidism. Myxedema refers to altered mental status observed in these patients. Clinical characteristics observed include hypothermia, bradycardia, respiratory failure, hyponatremia, and altered mental status. We present the case of a 57-year-old female who was brought into the hospital with a history of collapse and a long lie. On initial assessment, she was hypothermic, hypotensive, bradycardic, and hypoglycemic with elevated infection markers, acute kidney injury, and electrolyte derangement. Her thyroid function tests on admission were severely impaired with a TSH (thyroid stimulating hormone) level of 144.46 mU/L and Free T4 (thyroxine) levels of 3.4 pmol/L. She was admitted to the intensive care unit and was started on intravenous antibiotics, intravenous liothyronine, oral levothyroxine, and intravenous hydrocortisone. Initially, her hypothermia and bradycardia were slow to respond to treatment measures, but following the introduction of liothyronine, she showed marked improvement. Over the next few days, her infection markers improved, her acute kidney injury resolved, and her thyroid function tests normalized. Liothyronine was stopped after 6 days, levothyroxine was continued at her regular dose of 175 micrograms, and she was safely discharged with outpatient endocrinology follow-up.