Treating Hypothyroidism with Thyroxine/Triiodothyronine Combination Therapy in Denmark: Following Guidelines or Following Trends?

Potential Risks and Benefits of Desiccated Thyroid Extract for the Treatment of Hypothyroidism: A Systematic Review

Background: Desiccated thyroid extract (DTE) is no longer recommended for the treatment of hypothyroidism but is still in use. This review aimed to summarize the available literature on treatment with DTE in adult patients with hypothyroidism. Methods: The search was conducted up until January 6, 2024, in six electronic databases. Two reviewers independently screened all the search results. The retrieved studies compared DTE treatment with levothyroxine or combination therapy with liothyronine and levothyroxine. The primary outcome was quality of life (QoL), and the secondary outcomes included symptoms, treatment preference, adverse effects, thyroid hormone levels, thyroid autoantibodies, cardiovascular measures, and gene polymorphisms in deiodinase enzymes. Results: In the qualitative synthesis, we included nine nonrandomized studies of interventions (NRSIs), two randomized clinical trials (RCTs), and three case reports. The overall quality of evidence was moderate to very low for the various outcomes. The RCTs found no difference between treatments regarding QoL and symptom score assessments. In the NRSIs, symptom and QoL assessments were in favor of DTE. The included studies indicated that DTE may cause an increase in heart rate, lower body weight, and lower high-density lipoprotein compared with other treatment regimens, but results were conflicting. Conclusions: Most studies of DTE treatment are hampered by an inferior design, and data on long-term effects and side effects are lacking. Two RCTs could not demonstrate any difference in QoL or symptom scores when comparing DTE with other thyroid hormone substitutions. Future trials of DTE in patients with hypothyroidism should be based on adequate study designs, validated measures of QoL, patients with reduced QoL, and the assessment of biomarkers reflecting long-term adverse effects.

Hypothyroidism and Type D Personality: Results From E-MPATHY, a Cross-sectional International Online Patient Survey

CONTEXT

Between 10% and 15% of people with hypothyroidism experience persistent symptoms, despite achieving biochemical euthyroidism. The underlying causes are unclear. Type D personality (a vulnerability factor for general psychological distress) is associated with poor health status and symptom burden but has not been studied in people with hypothyroidism.

OBJECTIVE

To investigate type D personality in hypothyroidism and explore associations with other characteristics and patient-reported outcomes.

DESIGN

Multinational, cross-sectional survey.

SETTING

Online.

PARTICIPANTS

Individuals with self-reported, treated hypothyroidism.

INTERVENTION

Questionnaire.

MAIN OUTCOME MEASURES

Type D personality and associations with baseline characteristics, control of the symptoms of hypothyroidism by medication, satisfaction with care and treatment of hypothyroidism, impact of hypothyroidism on everyday living.

RESULTS

A total of 3915 responses were received, 3523 of which were valid. The prevalence of type D personality was 54.2%. Statistically significant associations were found between type D personality and several respondent characteristics (age, marital status, ethnicity, household income, comorbidities, type of treatment for hypothyroidism, most recent TSH level), anxiety, depression, somatization, poor control of the symptoms of hypothyroidism by medication, dissatisfaction with care and treatment of hypothyroidism, and a negative impact of hypothyroidism on everyday living).

DISCUSSION

Our study found a high prevalence of type D personality among people with hypothyroidism who responded to the survey. Type D personality may be an important determinant of dissatisfaction with treatment and care among people with hypothyroidism. Our findings require independent confirmation. Close collaboration between the disciplines of thyroidology and psychology is likely to be key in progressing our understanding in this area.

Patients' Persistent Symptoms, Clinician Demographics, and Geo-Economic Factors Are Associated with Choice of Therapy for Hypothyroidism by European Thyroid Specialists: The "THESIS" Collaboration

Background: Hypothyroidism is common, however, aspects of its treatment remain controversial. Our survey aimed at documenting treatment choices of European thyroid specialists and exploring how patients' persistent symptoms, clinician demographics, and geo-economic factors relate to treatment choices. Methods: Seventeen thousand two hundred forty-seven thyroid specialists from 28 countries were invited to participate in an online questionnaire survey. The survey included respondent demographic data and treatment choices for hypothyroid patients with persistent symptoms. Geo-economic data for each country were included in the analyses. Results: The response rate was 32.9% (6058 respondents out of 17,247 invitees). Levothyroxine (LT4) was the initial treatment preferred by the majority (98.3%). Persistent symptoms despite normal serum thyrotropin (TSH) while receiving LT4 treatment were reported to affect up to 10.0% of patients by 75.4% of respondents, while 28.4% reported an increasing such trend in the past 5 years. The principal explanations offered for patients' persistent symptoms were psychosocial factors (77.1%), comorbidities (69.2%), and unrealistic patient expectations (61.0%). Combination treatment with LT4+liothyronine (LT3) was chosen by 40.0% of respondents for patients who complained of persistent symptoms despite a normal TSH. This option was selected more frequently by female thyroid specialists, with high-volume practice, working in countries with high gross national income per capita. Conclusions: The perception of patients' dissatisfaction reported by physicians seems lower than that described by hypothyroid patients in previous surveys. LT4+LT3 treatment is used frequently by thyroid specialists in Europe for persistent hypothyroid-like symptoms even if they generally attribute such symptoms to nonendocrine causes and despite the evidence of nonsuperiority of the combined over the LT4 therapy. Pressure by dissatisfied patients on their physicians for LT3-containing treatments is a likely explanation. The association of the therapeutic choices with the clinician demographic characteristics and geo-economic factors in Europe is a novel information and requires further investigation.

Severity of hypothyroidism is inversely associated with impaired quality of life in patients referred to an endocrine clinic

PURPOSE

We investigated the association between health-related quality of life (HRQL) and the severity of hypothyroidism at diagnosis in patients referred to a secondary hospital clinic.

METHODS

Sixty-seven adult patients referred from primary care were enrolled. All patients had newly diagnosed hypothyroidism due to autoimmune thyroiditis and were treated with levothyroxine (LT4). The dose was adjusted according to thyroid function tests aiming at a normal plasma thyrotropin. Patients were stratified according to the severity of hypothyroidism in two different ways: the conventional approach (subclinical or overt hypothyroidism) and a novel approach according to the change (decrease or increase) in plasma level of free triiodothyronine index (FT3I) following LT4 treatment. The ThyPRO-39 questionnaire was used for measurement of HRQL at referral to the Endocrine Outpatient Clinic (higher score corresponds to worse HRQL).

RESULTS

Free thyroxine index (FT4I) at diagnosis correlated positively with the scores on the Hypothyroid Symptoms and Tiredness scales (p = 0.018 for both). In accordance, patients with subclinical hypothyroidism (n = 36) scored higher on Hypothyroid Symptoms (p = 0.029) than patients with overt hypothyroidism (n = 31). The difference in HRQL was more pronounced if patients were stratified according to the dynamics in FT3I following LT4 treatment. Thus, patients who showed a decrease in FT3I following treatment (n = 24) scored significantly worse for Anxiety (p = 0.032) and Emotional Susceptibility (p = 0.035) than patients with an increase in FT3I (n = 43).

CONCLUSION

Patients referred to an endocrine clinic with mild hypothyroidism had an impaired HRQL, compared to patients with more severe hypothyroidism. The most likely explanation of this finding is a lower threshold for seeking medical consultation and secondary care referral if HRQL is deteriorated. The dynamics in plasma FT3I following treatment may be more sensitive for such a discrimination in HRQL than a stratification according to the thyroid function tests at diagnosis.

Hypothyroidism and Somatization: Results from E-Mode Patient Self-Assessment of Thyroid Therapy, a Cross-Sectional, International Online Patient Survey

Background: Between 10% and 15% of hypothyroid patients experience persistent symptoms despite achieving biochemical euthyroidism. Unexplained persistent symptoms can be a sign of somatization. This is associated with distress and high health care resource use and can be classified as somatic symptom disorder (SSD). Prevalence rates for SSD differ depending on classification criteria and how they are ascertained, varying between 4% and 25%. As this has not been studied in hypothyroid patients before, the aim of this study was to document somatization in people with hypothyroidism and to explore associations with other patient characteristics and outcomes. Methods: Online, multinational cross-sectional survey of individuals with self-reported, treated hypothyroidism, which included the validated Patient Health Questionnaire-15 (PHQ-15) for assessment of somatization. Chi-squared tests with the Bonferroni correction were used to explore outcomes for respondents with a PHQ-15 score ≥10 (probable somatic symptom disorder [pSSD]) versus a PHQ-15 score <10 (absence of SSD). Results: A total of 3915 responses were received, 3516 of which contained the valid PHQ-15 data (89.8%). The median score was 11.3 (range 0-30 [confidence interval 10.9-11.3]). The prevalence of pSSD was 58.6%. Associations were found between pSSD and young age (p < 0.001), women (p < 0.001), not working (p < 0.001), having below average household income (p < 0.001), being treated with levothyroxine (LT4) (rather than combination of LT4 and L-triiodothyronine [LT3], LT3 alone, or desiccated thyroid extract) (p < 0.001), expression of the view that the thyroid medication taken did not control the symptoms of hypothyroidism well (p < 0.001), and with number of comorbidities (p < 0.001). pSSD was associated with respondent attribution of most PHQ-15 symptoms to the hypothyroidism or its treatment (p < 0.001), dissatisfaction with care and treatment of hypothyroidism (p < 0.001), a negative impact of hypothyroidism on daily living (p < 0.001), and with anxiety and low mood/depression (p < 0.001). Conclusions: This study demonstrates a high prevalence of pSSD among people with hypothyroidism and associations between pSSD and negative patient outcomes, including a tendency to attribute persistent symptoms to hypothyroidism or its treatment. SSD may be an important determinant of dissatisfaction with treatment and care among some hypothyroid patients.

Levothyroxine Monotherapy: What Works Better for the Individual With Hypothyroidism?

OBJECTIVE

I explore objective data not supporting the addition of liothyronine (medication) (LT3) to levothyroxine (medication) (LT4) in patients with hypothyroidism. Accurate identification of patients with symptomatic (almost exclusively overt) hypothyroidism is important in evaluating clinical outcomes of therapies. Recent studies have documented that nearly a third of individuals who are offered thyroid hormone are euthyroid at the time of initiation. Additionally, others are clinically diagnosed without biochemical confirmation, so a sizable proportion of those started on LT4 are not hypothyroid. The assumption that nonhypothyroid symptoms will resolve with LT4 is problematic. The true underlying cause of these symptoms remains unidentified and untreated.

METHODS

In a narrative fashion I will review the positive predictive value of and correlation of symptoms consistent with hypothyroidism and confirmed hypothyroidism likely to favorably respond to thyroid hormone replacement.

RESULTS

Following a review of the reliability of thyroid-stimulating hormone (TSH) in predicting a euthyroid state, the correlation of circulating triiodothyronine (serum measurement) (T3) levels with symptoms and predictive value of T3 to forecast the outcome of adding LT3 to LT4 will be reviewed. The utility of striving for high, middle, or low TSH set points within the expected range to predict changes in clinical quality of life and the ability of blinded patients to sense subtle differences along this spectrum will be documented. In addition, the clinical impact of single nucleotide polymorphisms in the type 2 deiodinase gene will be reviewed. Finally, the overall satisfaction of selected patients with their thyroid hormone treatments will be outlined and preferences for T3-containing treatments from blinded studies will be summarized.

CONCLUSION

Basing thyroid hormone treatment decisions on patient symptoms likely results in missed diagnoses We should encourage primary care physicians to assess a differential diagnosis, exclude other diagnoses, and not assume a thyroid etiology when TSH is normal. Modifying treatment to a particular TSH target or adjusting based on a low T3 level does not seem to enhance patient outcomes. Finally, pending further trials of "symptomatic" participants, using sustained release LT3 to mimic normal physiology, and including monocarboxylate 10 transporter and Type 2 deiodinase polymorphisms and objective outcomes, I will continue to depend on therapy with LT4 monotherapy and seek alternative explanations for my patients' nonspecific symptoms.

Socioeconomic influence on treatment with liothyronine and desiccated thyroid extract in Denmark

Introduction

High compared with low educational level increases the odds of starting levothyroxine (L-T4) with a normal thyroid-stimulating hormone - the mechanism is most likely patient request. The use of liothyronine (L-T3) and desiccated thyroid extract (DTE) is also speculated to be initiated at patients' request. Therefore, the primary aim of this study was to evaluate if educational level influences treatment with L-T3 and DTE.

Material and methods

In this register-based cross-sectional study, we included all Danish citizens ≥30 years with redeemed prescription of L-T4, L-T3, or DTE during 2017-2020. We defined educational levels as short, medium, and long (<10 years, 10-12 years, and above 12 years, respectively). The association between educational level and treatment with LT3 or DTE vs only LT4 was analyzed in logistic regression models adjusted for age and sex.

Results

We included 154,360 individuals using thyroid medication of whom 3829 were treated with L-T3 (2.48%) and 430 with DTE (0.28%). The usage was highest among women (3.15%) and the age group 40-49 (5.6%). Longer education compared with short increased the odds of being treated with DTE or L-T3 (medium education odds ratio (OR) 1.61 (95% CI 1.50-1.8) and long education OR 1.95 (95% CI 1.79-2.13)). Test for trend: OR: 1.37 (95% CI 1.31-1.42). Adjustment for other covariates did not affect the results substantially.

Conclusion

Persons with a longer compared to a shorter education are more often treated with either DTE or L-T3, and the usage of these drugs is limited to less than 3% of thyroid hormone users.

Combined T4 + T3 therapy versus T4 monotherapy effect on psychological health in hypothyroidism: A systematic review and meta-analysis

PURPOSE

To evaluate whether T4 + T3 combination therapy had advantages in improving psychological health compared with T4 monotherapy.

METHODS

We searched PubMed, Embase, Cochrane Library, and Web of Science from January 2000 to March 2021, and updated in September 2021. The inclusion criteria (prospective study, published in English, had a T4 + T3 combination therapy test group and a T4 monotherapy control group, patients aged ≥18 years and with overt primary hypothyroidism, and published after January 2000) were applied by two reviewers; any disagreement was resolved by a third reviewer. The two reviewers independently extracted data using a standard data form and assessed the risk of bias using the Cochrane risk of bias tool. Coprimary outcomes included the psychological health measures of depression, fatigue, pain, anxiety and anger, measured using validated and reliable instruments.

RESULTS

Eighteen of 2029 studies (883 patients) were included in the meta-analysis. No significant difference was found between T4 + T3 combination therapy and T4 monotherapy with regard to depression (standardized mean difference [SMD]: -0.06, 95% confidence interval [CI]: -0.18; 0.07), fatigue (SMD: 0.06, 95% CI: -0.13; 0.26), pain (SMD: -0.01, 95% CI: -0.24; 0.22), anxiety (SMD: 0.01, 95% CI: -0.15; 0.17) and anger (SMD: 0.05, 95% CI: -0.15; 0.24). Methodological heterogeneity had no influence on the results. The patients preferred combination therapy significantly.

CONCLUSIONS

Compared with T4 monotherapy, T4 + T3 combination therapy had no significant advantage in improving psychological health. For patients who are unsatisfied with LT4 monotherapy, the patient and the physician should make a joint decision concerning therapy.

Heart Failure and Stroke Risks in Users of Liothyronine With or Without Levothyroxine Compared with Levothyroxine Alone: A Propensity Score-Matched Analysis

Background: Combination therapy with liothyronine (LT3) and levothyroxine (LT4) is used in patients with persistent symptoms, despite being administered an adequate dose of LT4. LT3 may also be used in some thyroid cancer patients preparing for radioactive iodine therapy. However, there is a controversy regarding the safety of LT3 use, and there has been no definite evidence of long-term safety of LT3 therapy in Asian populations. The aim of this study was to examine the long-term safety of LT3 therapy using the Common Data Model (CDM). Methods: We conducted a retrospective multicenter study across four hospital databases encoded in the Observational Medical Outcomes Partnership (OMOP) CDM. LT3 users were defined as those who received an LT3 prescription for at least 90 days (with or without LT4), and their safety outcomes were compared with those in LT4-only users after 1:4 propensity score matching. Safety outcomes included the incidences of osteoporosis, cardiovascular disease, cancer, anxiety disorder, and mood disorder. Results: We identified 1434 LT3 users and 3908 LT4-only users. There was a statistically significant difference in the incidence rate of safety outcomes between LT3 users and LT4-only users. The risks of heart failure (incidence rate ratio [IRR] = 1.664, 95% confidence interval [95% CI] 1.002-2.764, p = 0.049) and stroke (IRR = 1.757, CI 1.073-2.877, p = 0.025) were higher in LT3 users than in LT4-only users. When subgroup analysis was performed according to the presence/absence of thyroid cancer history and duration of thyroid hormone replacement, the risk of heart failure was higher in LT3 users with a history of thyroid cancer and those who underwent ≥52 weeks of LT3 therapy. In addition, the risk of stroke was higher in LT3 users without thyroid cancer history and those who underwent ≥52 weeks of LT3 therapy. Conclusions: The use of LT3 was associated with increased incidence of heart failure and stroke in patients with a longer duration of LT3 use and history of thyroid cancer. Therefore, clinicians should consider the risk of heart failure and stroke in thyroid cancer patients with long-term use of LT3. These findings require confirmation in other populations.

A Questionnaire Survey of German Thyroidologists on the Use of Thyroid Hormones in Hypothyroid and Euthyroid Patients: The THESIS (Treatment of Hypothyroidism in Europe by Specialists: An International Survey) Collaborative

OBJECTIVE

To identify the attitudes of German thyroid specialists towards the clinical treatment of hypothyroidism using thyroid hormones (TH).

METHODS

All members of the thyroid section of the German Endocrine Society (DGE) were e-mailed an invitation to participate in a web-based survey about substitution with TH.

RESULTS

Out of 206 members of the DGE's thyroid section, 163 (79.1%) responses were received and included in the analysis. Of responding members, 98.6% used levothyroxine (LT4) as the treatment of choice, and 45.4% also prescribed combination therapy with liothyronine (LT4+LT3) in their clinical practice (p<0.001). LT4+LT3 combination was favored in patients with persistent hypothyroidism symptoms despite biochemical euthyroidism on LT4 treatment (p<0.001). Of all respondents, 26.4% never indicated TH therapy for euthyroid patients (p<0.001), while the remainder would consider THs for one or more indications (62.9% for euthyroid infertile women with high anti-thyroid antibody levels (p<0.001), 7.1% in patients with severe hypercholesterolemia, as complementary treatment (p=0.007), and 57.1% in patients with simple goiter (p<0.001)). In conditions that could interfere with LT4 absorption, most respondents still preferred tablets and did not expect a significant difference when switching from one LT4 formulation to another.

CONCLUSION

For German thyroid specialists, LT4 is the treatment of choice for hypothyroidism. Combination therapy with LT4+LT3 was considered for patients with persistent symptoms. Even in conditions that could affect bioavailability, German thyroid specialists prefer LT4 tablets rather than other LT4 formulations, such as liquid or soft-gel capsules. The widespread use of thyroid hormone for non-hypothyroid conditions is not consistent with current evidence and needs further study.

Enhanced Well-Being Associated with Thyrotoxicosis: A Neglected Effect of Thyroid Hormones?

CONTEXT

Thyrotoxicosis may be associated with a better sense of well-being than in the euthyroid state, though this is not widely recognised.

EVIDENCE ACQUISITION

A comprehensive literature search in PubMed and Google Scholar, was performed to identify studies investigating factors influencing well-being, mood, and psychological features associated with elevated thyroid hormones.

RESULTS

Enhanced well-being associated with thyrotoxicosis has been described, although the evidence is observational and anecdotal.

CONCLUSIONS

Enhanced well-being associated with thyrotoxicosis is probably experienced in a minority of patients and may explain why some seek overtreatment with thyroid hormones and report significant improvement on larger than physiological thyroid hormone replacement regimens. It may also explain why some patients with hyperthyroidism (usually due to Graves' disease) are reluctant to adhere to anti-thyroid medication.

[Features of the use of synthetic analogues of thyroid hormones: а 2020 THESIS* questionnaire survey of members of the Belarusian Public Medical Association of Endocrinology and Metabolism]

BACKGROUND

The standard treatment for hypothyroidism is levothyroxine (LT4), which in the Republic of Belarus is available in tablet form whereas liothyronine (LT3) is not registered, but patients can purchase them on their own abroad.

AIM

This study aimed to investigate Belarusian endocrinologists' attitude of thyroid hormones in hypothyroid and euthyroid patients.

MATERIALS AND METHODS

An online survey was conducted, for which members of the Belarusian Medical Association of Endocrinology and Metabolism were invited by posting information in the group chat and by e-mail. The research period was from October 1 to December 26, 2020. 210 questionnaires were received, 146 of which were used.

RESULTS

The majority of participants, 145 (99.3%), indicated that they were using LT4 as the first-choice drug for the treatment hypothyroidism. Sixty-one (41.8%) doctors answered that LT3 + LT4 combination likely can be used in patients with long-term untreated hypothyroidism and 15 (10.3%) - in patients with persistent symptoms of hypothyroidism, despite biochemical euthyroidism on therapy LT4. Over half of the respondents 84 (57.5%) answered that thyroid hormone therapy was never indicated for euthyroid patients, but 50 (34.2%) would consider it for female infertility with high level of thyroid antibodies and 36 (24.7%) for simple goiter growing over time. In various conditions that could interfere with absorption of LT4, most responding Belarusian endocrinologists do not expect a significant difference with different formulations (tablets+"I do not expect major changes in different forms" vs. "soft gel capsules"+"liquid solution"; p &lt;0.001). Persistent symptoms of hypothyroidism on the background of LT4 replacement therapy with the achievement of the target TSH can mainly be caused by psychosocial factors, concomitant diseases, unrealistic patient expectations, chronic fatigue syndrome, and the burden of chronic disease.

CONCLUSION

The method of choice of Belarusian endocrinologists in the treatment of hypothyroidism is LT4 replacement therapy, but the appointment of LT4 + LT3 combination therapy can be considered in certain clinical situations. As a rule, endocrinologists do not prescribe LT4 in patients with euthyroidism and do not expect a significant difference when using other forms of levothyroxine.

Triiodothyronine alongside levothyroxine in the management of hypothyroidism?

The current guideline-based management of hypothyroidism recommends monotherapy with levothyroxine (LT4), titrated to maintain the level of thyrotropin within a euthyroid reference range. This has been successful for most people with hypothyroidism, but a substantial minority still report symptoms of hypothyroidism unexplained by a comorbid medical condition. LT4 is essentially a prodrug for triiodothyronine (T3), the thyroid hormone that acts on target tissues in the brain and the periphery. Thyroid hormone replacement with LT4 alone does not restore physiological tissue levels of thyroid hormones, particularly T3. During the last two decades, much interest has focussed on the potential of combinations of LT4 and T3 to provide a superior outcome to LT4 monotherapy for people with hypothyroidism, especially those with residual symptoms despite thyrotropin-optimized LT4. This review seeks to provide an overview of currently available evidence on combination (LT4 + T3) therapy to be used for personalized medicine in patients with hypothyroidism. A number of randomized, controlled trials (RCTs) have failed to demonstrate superiority for the combination therapy approach, largely due to non-physiological T3 doses. However, patients with hypothyroidism are highly heterogeneous in terms of their residual thyroid function, individual set points for optimal thyroid homeostasis and for the presence or absence of polymorphisms in deiodinase enzymes in tissues that activate and deactivate circulating thyroid hormones. Accordingly, these RCTs may have failed to demonstrate benefits of combination therapy in individual hypothyroid phenotypes. The pharmacokinetics of LT4 and T3 also differ, which is a barrier to their co-administration. Future clinical trials using LT4 + T3 tablets better suited for combination therapy will resolve the outstanding research questions relating to the place of LT4 + T3 combination therapy in the management of hypothyroidism.

Levothyroxine Treatment and the Risk of Cardiac Arrhythmias - Focus on the Patient Submitted to Thyroid Surgery

Levothyroxine (LT4) is used to treat frequently encountered endocrinopathies such as thyroid diseases. It is regularly used in clinical (overt) hypothyroidism cases and subclinical (latent) hypothyroidism cases in the last decade. Suppressive LT4 therapy is also part of the medical regimen used to manage thyroid malignancies after a thyroidectomy. LT4 treatment possesses dual effects: substituting new-onset thyroid hormone deficiency and suppressing the local and distant malignancy spreading in cancer. It is the practice to administer LT4 in less-than-high suppressive doses for growth control of thyroid nodules and goiter, even in patients with preserved thyroid function. Despite its approved safety for clinical use, LT4 can sometimes induce side-effects, more often recorded with patients under treatment with LT4 suppressive doses than in unintentionally LT4-overdosed patients. Cardiac arrhythmias and the deterioration of osteoporosis are the most frequently documented side-effects of LT4 therapy. It also lowers the threshold for the onset or aggravation of cardiac arrhythmias for patients with pre-existing heart diseases. To improve the quality of life in LT4-substituted patients, clinicians often prescribe higher doses of LT4 to reach low normal TSH levels to achieve cellular euthyroidism. In such circumstances, the risk of cardiac arrhythmias, particularly atrial fibrillation, increases, and the combined use of LT4 and triiodothyronine further complicates such risk. This review summarizes the relevant available data related to LT4 suppressive treatment and the associated risk of cardiac arrhythmia.

Use of thyroid hormones in hypothyroid and euthyroid patients: A 2020 THESIS questionnaire survey of members of the Danish Endocrine Society

PURPOSE

The standard treatment of hypothyroidism is levothyroxine (LT4), which is available as tablets or soft-gel capsules in Denmark. This study aimed to investigate Danish endocrinologists' use of thyroid hormones in hypothyroid and euthyroid patients.

METHODS

An e-mail with an invitation to participate in an online survey investigating practices about substitution with thyroid hormones was sent to all members of the Danish Endocrine Society (DES).

RESULTS

Out of 488 eligible DES members, a total of 152 (31.2%) respondents were included in the analysis. The majority (94.1%) of responding DES members use LT4 as the treatment of choice. Other treatment options for hypothyroidism are also used, as 58.6% prescribe combination therapy with liothyronine (LT3) + LT4 in their clinical practice. LT4 + LT3 combination is preferred in patients with persistent symptoms of hypothyroidism despite biochemical euthyroidism on LT4 treatment. Over half of the respondents answered that thyroid hormone therapy is never indicated for euthyroid patients, but 42.1% will consider it for euthyroid infertile women with high antibody levels. In various conditions that could interfere with the absorption of LT4, most responding Danish endocrinologists prefer tablets and do not expect a significant difference when switching from one type of tablet formulation to another.

CONCLUSION

The treatment of choice for hypothyroidism is LT4. Combination therapy with LT4 + LT3 is considered for patients with persistent symptoms. Even in the presence of conditions affecting bioavailability, responding Danish endocrinologists prefer LT4 tablets rather than newer LT4 formulations, such as soft-gel capsules.

T4+T3 Combination Therapy: An Unsolved Problem of Increasing Magnitude and Complexity

Thyroxine (T4)+triiodothyronine (T3) combination therapy can be considered in case of persistent symptoms despite normal serum thyroid stimulating hormone in levothyroxine (LT4)-treated hypothyroid patients. Combination therapy has gained popularity in the last two decades, especially in countries with a relatively high gross domestic product. The prevalence of persistent symptoms has also increased; most frequent are complaints about energy levels and fatigue (80% to 90%), weight management (70% to 75%), memory (60% to 80%), and mood (40% to 50%). Pathophysiological explanations for persistent problems are unrealistic patient expectations, comorbidities, somatic symptoms, related disorders (Diagnostic and Statistical Manual of Mental Disorders [DSM-5]), autoimmune neuroinflammation, and low tissue T3. There is fair circumstantial evidence for the latter cause (tissue and specifically brain T3 content is normalized by T4+T3, not by T4 alone), but the other causes are viewed as more relevant in current practice. This might be related to the 'hype' that has emerged surrounding T4+T3 therapy. Although more and better-designed trials are needed to validate the efficacy of T4+T3 combination, the management of persistent symptoms should also be directed towards alternative causes. Improving the doctor-patient relationship and including more and better information is crucial. For example, dissatisfaction with the outcomes of T4 treatment for subclinical hypothyroidism can be anticipated as recent trials have demonstrated that LT4 is hardly effective in improving symptoms associated with subclinical hypothyroidism.

The Correlation Between Low Serum T3 Levels and All-Cause and Cardiovascular Mortality in Peritoneal Dialysis Patients

Objective

This study is to investigate the correlation between serum triiodothyronine (T3) levels and all-cause and cardiovascular mortality in PD patients.

Methods

A total of 376 end-stage renal disease (ESRD) patients who started maintenance PD treatment in the Department of Nephrology in our hospital and stable treatment for ≥3 months were selected, and the total T3 (TT3) and free T3 (FT3) levels were determined. Among them, 168 cases with FT3 <3.5 pmol/L and/or TT3 <0.92 nmol/L were divided into the low serum T3 level group, and the remaining 208 cases were divided into normal serum T3 level group. The Cox survival analysis method was used to analyze the correlation between low serum T3 levels and all-cause and cardiovascular mortality in PD patient.

Results

Compared with the normal serum T3 level group, patients with low serum T3 levels had higher systolic blood pressure and a higher proportion of heart disease, and lower levels of total T4, free T4, hemoglobin, serum albumin, blood calcium, serum total bilirubin, alanine aminotransferase, and 24-h urine volume (all P < 0.05). Binary Logistic regression analysis showed that heart disease (P = 0.003, OR: 2.628, 95% CI: 1.382–4.997) and high TT4 level (P < 0.001, OR: 0.968, 95% CI: 0.956–0.979) were related to low serum T3 levels in PD patients. Multivariate Cox regression analysis showed that low serum FT3 level was an independent risk factor for all-cause death in PD patients (HR = 0.633, 95% CI = 0.431–0.930; P < 0.020).

Conclusion

Low serum T3 levels in PD patients were associated with heart disease and TT4 levels. Low serum FT3 levels were associated with the risk of all-cause death in PD patients.

Liothyronine Use in Hypothyroidism and its Effects on Cancer and Mortality

Background: The prescription of liothyronine (LT3) to treat hypothyroidism is increasing worldwide; however, the long-term safety of LT3 use has yet to be determined. Previous studies have suggested a possible association between LT3 use and breast cancer. The aim of this study was to examine the effects of LT3 use on cancer incidence and mortality. Methods: Our sample included the full adult population of individuals living in Sweden with at least three purchases of thyroid hormone therapy between July 2005 and December 2017. Individual-level data on drug purchases were linked to registry data on cancer incidence and mortality. There were 575,461 individuals with at least three purchases, of which 11,147 had made at least three purchases of LT3, including combinations of levothyroxine (LT4) and LT3. Individuals were followed for a median follow-up time of 8.1 years. We applied Cox regression with a time-varying exposure variable, comparing LT3 users (individuals with at least three cumulative purchases of LT3) with LT4-only users (the rest). Outcomes included breast cancer incidence, any cancer incidence, all-cause mortality, any cancer mortality, and breast cancer mortality. We adjusted for age, sex, previous thyroid cancer, previous other cancer, use of antithyroid preparations, use of sex hormones, and dose in multivariate analyses. Results: Multivariate analyses produced a hazard ratio of 0.93 (95% confidence interval [0.75-1.15]) for breast cancer incidence (only females), 0.97 (0.87-1.08) for any cancer incidence, 0.69 (0.61-0.77) for all-cause mortality, 0.78 (0.62-0.98) for any cancer mortality, and 0.91 (0.50-1.66) for breast cancer mortality (only females). Conclusions: In this large, Swedish, long-term registry-based study, the use of LT3 did not lead to increased breast cancer incidence, any cancer incidence, all-cause mortality, any cancer mortality, or breast cancer mortality compared with LT4 use. Somewhat surprisingly, there was evidence of lower mortality in LT3 users in models adjusting for dose, potentially an artifact of underlying associations between dose and health status/diagnosis.

Patient satisfaction and quality of life in hypothyroidism: An online survey by the british thyroid foundation

OBJECTIVE

Dissatisfaction with treatment and impaired quality of life (QOL) are reported among people with treated hypothyroidism. We aimed to gain insight into this.

DESIGN AND PATIENTS

We conducted an online survey of individuals with self-reported hypothyroidism.

RESULTS

Nine hundred sixty-nine responses were analysed. Dissatisfaction with treatment was common (77.6%), and overall QOL scores were low. Patient satisfaction did not correlate with type of thyroid hormone treatment, but treatment with combination levothyroxine (L-T4) and liothyronine (L-T3) or with desiccated thyroid extract (DTE) was associated with significantly better reported QOL than L-T4 or L-T3 monotherapies (P < .001); however, multivariate analysis inclusive of other clinical parameters failed to confirm an association between type of thyroid hormone treatment and QOL or satisfaction. Multivariate analysis showed positive correlations between satisfaction and age (P = .026), male gender (P = .011), being under the care of a thyroid specialist (P < .001), family doctor (GP) prescribing DTE or L-T4 + L-T3 or L-T3 (P < .001) and being well informed about hypothyroidism (P < .001); negative correlations were observed between satisfaction and negative experiences with L-T4 (P < .001) and expectations for more support from the GP (P < .001), for L-T4 to resolve all symptoms (P = .004), and to be referred to a thyroid specialist (P < .001). For QOL, positive correlations were with male gender (P = .011) and duration of hypothyroidism (P = .002); negative correlations were with age (P = .027), visiting the GP more than 3 times before diagnosis (P < .001), sourcing DTE or L-T3 independently (P = .014), negative experiences with L-T4 (P = .013), having expectations for L-T4 to resolve all symptoms (P < .001) and of more support from the GP (P = .006).

CONCLUSIONS

Multiple parameters including prior healthcare experiences and expectations influence satisfaction with hypothyroidism treatment and QOL. Focusing on enhancing the patient experience and clarifying expectations at diagnosis may improve satisfaction and QOL.

Use of Thyroid Hormones in Hypothyroid and Euthyroid Patients: A 2020 THESIS Questionnaire Survey of Members of the Swedish Endocrine Society

BACKGROUND

The standard treatment of hypothyroidism is levothyroxine (LT-4). However, there are several controversies regarding treatment of hypothyroid patients.

AIM

To investigate the Swedish endocrinologists' use of thyroid hormones in hypothyroid and euthyroid individuals.

METHODS

Physician members of the Swedish Endocrine Society (SEF) were invited by e-mail to participate in an online survey investigating this topic.

RESULTS

Out of the eligible 411 members, 116 (28.2%) responded. The majority (98.9%) stated that L-T4 is the treatment of choice. However, around 50% also prescribed liothyronine (L-T3) or a combination of L-T4+L-T3 in their practice. Combination therapy was mostly (78.5%) used in patients with persistent hypothyroid symptoms despite biochemical euthyroidism on L-T4 treatment. Most respondents prescribed L-T4 tablets and did not expect any major changes with alternative formulations such as soft-gel capsules or liquid formulations in situations influencing the bioavailability of L-T4. In euthyroid patients, 49.5% replied that treatment with thyroid hormones was never indicated, while 47.3% would consider L-T4 for euthyroid infertile women with high thyroid peroxidase (TPO) antibody levels.

CONCLUSION

The treatment of choice for hypothyroidism in Sweden is L-T4 tablets. Combination therapy with L-T4+L-T3 tablets was considered for patients with persistent symptoms despite biochemical euthyroidism. Soft-gel capsules and liquid solutions of L-T4 were infrequently prescribed. Swedish endocrinologists' deviation from endocrine society guidelines merits further study.

The Role of Inositol in Thyroid Physiology and in Subclinical Hypothyroidism Management

Myo-Inositol (MYO) is the most abundant stereoisomer of inositols' family, cyclic polyols with 6 hydroxyl groups. Myo-Inositol has a relevant role in thyroid function and autoimmune diseases, as a precursor of phosphoinositides that takes part in the phosphatidylinositol (PI) signal transduction pathway. Among phosphoinositides, phosphatidylinositol 4,5- bisphosphate (PIP2) is the precursor of inositol triphosphates (IP3), second messenger of several hormones including thyroid-stimulating hormone (TSH). As a second messenger in the phospholipase C (PLC)-dependent inositol phosphate Ca²⁺/DAG pathway, Myo-Inositol is essential to produce H₂O₂ required for the synthesis of thyroid hormones. Consequently, depletion of Myo-Inositol or impaired inositol dependent TSH signaling pathway may predispose to the development of some thyroid diseases, such as hypothyroidism. Many clinical studies have shown that after treatment with Myo-Inositol plus Selenium (MYO+Se), TSH levels significantly decreased in patients with subclinical hypothyroidism with or without autoimmune thyroiditis. The TSH reduction was accompanied by a decline of antithyroid autoantibodies. Moreover, Myo-Inositol supplementation seemed to be involved also in the management of thyroidal benign nodules, with a possible effect in the size reduction. This review proposes a summary of the role of inositol, especially of Myo-Inositol, in the thyroidal physiology and its contribution on the management of some thyroid diseases.

Managing symptoms in hypothyroid patients on adequate levothyroxine: a narrative review

The current standard of care for hypothyroidism is levothyroxine (LT4) monotherapy to reduce levels of thyrotropin (thyroid-stimulating hormone, TSH) within its reference range and amelioration of any symptoms. A substantial minority continues to report hypothyroid-like symptoms despite optimized TSH, however. These symptoms are not specific to thyroid dysfunction and are frequent among the euthyroid population, creating a therapeutic dilemma for the treating clinician as well as the patient. We present a concise, narrative review of the clinical research and evidence-based guidance on the management of this challenging population. The clinician may endeavor to ensure that the serum TSH is within the target range. However, the symptomatic patient may turn to alternative non-evidence-based therapies in the hope of obtaining relief. Accordingly, it is important for the clinician to check for conditions unrelated to the thyroid that could account for the ongoing symptoms such as other autoimmune conditions, anemia or mental health disorders. Systematic and thorough investigation of the potential causes of persistent symptoms while receiving LT4 therapy will resolve the problem for most patients. There may be some patients that may benefit from additional treatment with liothyronine (LT3), although it is unclear as yet as to which patient group may benefit the most from combined LT4 + LT3 therapy. In the future, personalized treatment with LT4 + LT3 may be of benefit for some patients with persistent symptoms of hypothyroidism such as those with polymorphisms in the deiodinase enzyme 2 (DIO2). For now, this remains a subject for research.

Patient Experiences and Perceptions Associated with the Use of Desiccated Thyroid Extract

Background and objectives: It is unclear why many patients with hypothyroidism prefer the use of desiccated thyroid extract (DTE) as a thyroid hormone replacement formulation over levothyroxine (LT4) treatment, as recommended by clinical practice guidelines. We analyzed patient-reported information from patient online forums to better understand patient preferences for and attitudes toward the use of DTE to treat hypothyroidism. Materials and Methods: We conducted a mixed-methods study by evaluating the content of online posts from three popular hypothyroidism forums from patients currently taking DTE (n = 673). From these posts, we extracted descriptive information on patient demographics and clinical characteristics and qualitatively analyzed posts’ content to explore patient perceptions on DTE and other therapies further. Results: Nearly half (46%) of the patients reported that a clinician initially drove their interest in trying DTE. Patients described many reasons for switching from a previous therapeutic approach to DTE, including lack of improvement in hypothyroidism-related symptoms (58%) and the development of side effects (22%). The majority of patients described DTE as moderately to majorly effective overall (81%) and more effective than the previous therapy (77%). The most frequently described benefits associated with DTE use were an improvement in symptoms (56%) and a change in overall well-being (34%). One-fifth of patients described side effects related to the use of DTE. Qualitative analysis of posts’ content supported these findings and raised additional issues around the need for individualizing therapy approaches for hypothyroidism (e.g., a sense of each patient has different needs), as well as difficulties obtaining DTE (e.g., issues with pharmacy availability). Conclusions: Lack of individualized treatment and a feeling of not been listened to were recurrent themes among DTE users. A subset of patients may prefer DTE to LT4 for many reasons, including perceived better effectiveness and improved overall well-being, despite the risks associated with DTE.

LT4 and Slow Release T3 Combination: Optimum Therapy for Hypothyroidism?

CONTEXT

Levothyroxine (LT4) is recommended as replacement therapy for thyroid hormone deficiency. However, some hypothyroid patients receiving LT4 therapy do not feel as well as healthy subjects. This article aimed to review current knowledge regarding LT4 monotherapy versus LT4+LT3 combination therapy and propose future directions regarding LT4+slow release T3 combination treatment for hypothyroidism.

EVIDENCE ACQUISITION

We searched PubMed and Scopus using related keywords.

RESULTS

The LT4 monotherapy causes higher serum free T4 (fT4), subnormal serum free T3 (fT3), and fT3/fT4 ratio in one-fourth of patients. The LT4+LT3 combination therapy increases serum T3 and fT3 concentrations and may normalize the fT3/fT4 ratio. However, the primary outcomes, including thyroid hormone deficiency, anxiety, depression, and quality of life, may not be better in LT4+LT3 combination therapy than in LT4 monotherapy. Recent surveys show that combination therapy is on the rise, in particular, due to patient demand. The LT4 plus slow-release LT3 preparation has shown promising results in improving serum thyroid hormone concentrations.

CONCLUSIONS

The beneficial effect of LT4+LT3 combination therapy is not clear, and the safety of long-term therapy is yet under question. More scientific well-designed research projects are required in this field.

Use of Thyroid Hormones in Hypothyroid and Euthyroid Patients; the 2019 Italian Survey

BACKGROUND

The incidence and prevalence of hypothyroidism are increasing and the threshold for the treatment of hypothyroid as well as individuals without evident thyroid disease with thyroid hormone is declining.

OBJECTIVE

To investigate endocrinologists' use of thyroid hormones in hypothyroid and euthyroid patients in Italy, a country where different formulations of levothyroxine (LT4; tablet, liquid solution and soft-gel capsule) are available on the market.

METHODS

Members of the Associazione Medici Endocrinologi (Italian Association of Clinical Endocrinologists) were invited to participate in a web-based survey investigating the topic.

RESULTS

A total of 797 of 2,028 (39.3%) members completed all the sections of the survey; 98.7% declared that the treatment of choice for hypothyroidism is LT4. A significant minority (37.3%) indicated that LT4 may be considered in infertile euthyroid women seeking pregnancy and harbouring positive thyroperoxidase antibodies (TPOAb) and in goitre increasing in size (18.1%). LT4 + LT3 was considered by 43.2% for LT4-replaced patients and normal TSH, if they reported persistent symptoms. High percentages of respondents chose LT4 in a liquid solution or soft-gel capsules when taken together with other drugs interfering with LT4 absorption (81.8%), in patients with a history of celiac disease, malabsorption, lactose intolerance, intolerance to common excipients (96.6%), or unexplained poor biochemical control of hypothyroidism (74.4%), or in patients not able to adhere to ingesting LT4 fasted and/or separated from food/drink (98.9%). In total, 43.6% of responders would use LT4 in a liquid solution or soft-gel capsules for hypothyroid patients with biochemical euthyroidism on LT4, who had persistent symptoms.

CONCLUSIONS

The preferred treatment for hypothyroidism is LT4; LT3 + LT4 combination treatment is mainly considered in patients with persistent symptoms. A significant minority would offer LT4 to euthyroid women with positive TPOAb and infertility and to euthyroid patients with progressive simple goitre. Alternative LT4 formulations like liquid solution or soft-gel capsules are largely reserved for specific conditions (interfering drugs, actual or suspected malabsorption, inability to take LT4 in the fasting state, unexplained poor biochemical control of hypothyroidism).

T4 + T3 combination therapy: any progress?

Guidelines on T4 + T3 combination therapy were published in 2012. This review investigates whether the issue is better understood 7 years later. Dissatisfaction with the outcome of T4 monotherapy remains high. Persistent symptoms consist mostly of fatigue, weight gain, problems with memory and thinking and mood disturbances. T4 monotherapy is associated with low serum T3 levels, which often require TSH-suppressive doses of L-T4 for normalization. Peripheral tissue thyroid function tests during T4 treatment indicate mild hyperthyroidism at TSH < 0.03 mU/L and mild hypothyroidism at TSH 0.3-5.0 mU/L; tissues are closest to euthyroidism at TSH 0.03-0.3 mU/L. This is explained by the finding that whereas T4 is usually ubiquinated and targeted for proteasomal degradation, hypothalamic T4 is rather stable and less sensitive to ubiquination. A normal serum TSH consequently does not necessarily indicate a euthyroid state. Persistent symptoms in L-T4 treated patients despite a normal serum TSH remain incompletely understood. One hypothesis is that a SNP (Thr92Ala) in DIO2 (required for local production of T3 out of T4) interferes with its kinetics and/or action, resulting in a local hypothyroid state in the brain. Effective treatment of persistent symptoms has not yet realized. One may try T4 + T3 combination treatment in selected patients as an experimental n = 1 study. The 2012 ETA guidelines are still valid for this purpose. More well-designed randomized clinical trials in selected patients are key in order to make progress. In the meantime the whole issue has become rather complicated by commercial and political overtones, as evident from skyrocketing prices of T3 tablets, aggressive pressure groups and motions in the House of Lords.

Thyroid hormone therapy for hypothyroidism

The purpose of this article will be to review the basics of thyroid hormone therapy, including various thyroid hormone formulations, the institution and monitoring of thyroid hormone therapy, adverse effects of overtreatment, the management of patients with persistent symptoms despite normal thyroid function tests, and potential new innovations in thyroid hormone therapy. The conclusions support the necessity to personalize thyroid hormone replacement therapy in hypothyroid patients.

Individualised requirements for optimum treatment of hypothyroidism: complex needs, limited options

Levothyroxine (LT4) therapy has a long history, a well-defined pharmacological profile and a favourable safety record in the alleviation of hypothyroidism. However, questions remain in defining the threshold for the requirement of treatment in patients with subclinical hypothyroidism, assessing the dose adequacy of the drug, and selecting the best treatment mode (LT4 monotherapy versus liothyronine [LT3]/LT4 combinations) for subpopulations with persisting complaints. Supplied as a prodrug, LT4 is enzymatically converted into the biologically more active thyroid hormone, triiodothyronine (T3). Importantly, tetraiodothyronine (T4) to T3 conversion efficiency may be impaired in patients receiving LT4, resulting in a loss of thyroid-stimulating hormone (TSH)-mediated feed-forward control of T3, alteration of the interlocking equilibria between serum concentrations of TSH, free thyroxine (FT4), and free triiodothyonine (FT3), and a decrease in FT3 to FT4 ratios. This downgrades the value of the TSH reference system derived in thyroid health for guiding the replacement dose in the treatment situation. Individualised conditionally defined setpoints may therefore provide appropriate biochemical targets to be clinically tested, together with a stronger focus on clinical presentation and future endpoint markers of tissue thyroid state. This cautionary note encompasses the use of aggregated statistical data from clinical trials which are not safely applicable to the individual level of patient care under these circumstances.

The Colorful Diversity of Thyroid Hormone Metabolites

Since the discovery of L-thyroxine, the main secretory product of the thyroid gland, and its major metabolite T3, which exerts the majority of thyroid hormone action via ligand-dependent modulation of the function of T3 receptors in nuclei, mitochondria, and other subcellular compartments, various other T4-derived endogenous metabolites have been identified in blood and tissues of humans, animals, and early protochordates. This review addresses major historical milestones and experimental findings resulting in the discovery of the key enzymes of thyroid hormone metabolism, the three selenoprotein deiodinases, as well as the decarboxylases and amine oxidases involved in formation and degradation of recently identified endogenous thyroid hormone metabolites, i.e. 3-iodothyronamine and 3-thyroacetic acid. The concerted action of deiodinases 2 and 3 in regulation of local T3 availability is discussed. Special attention is given to the role of the thyromimetic "hot" metabolite 3,5-T2 and the "cool" 3-iodothyronamine, especially after administration of pharmacological doses of these endogenous thyroid hormone metabolites in various animal experimental models. In addition, available information on the biological roles of the two major acetic acid derivatives of thyroid hormones, i.e. Tetrac and Triac, as well as sulfated metabolites of thyroid hormones is reviewed. This review addresses the consequences of the existence of this broad spectrum of endogenous thyroid hormone metabolites, the "thyronome," beyond the classical thyroid hormone profile comprising T4, T3, and rT3 for appropriate analytical coverage and clinical diagnostics using mass spectrometry versus immunoassays for determination of total and free concentrations of thyroid hormone metabolites in blood and tissues.

Combination Thyroid Hormone Replacement; Knowns and Unknowns

Hypothyroidism is common throughout the world and readily diagnosed with thyroid function tests. Management should be straightforward but appears not to be the case. Thyroid hormone replacement with levothyroxine monotherapy is the standard treatment which is effective in the majority of cases. However, 10-15% of patients established on levothyroxine do not feel their health is entirely restored and some patients prefer the addition of liothyronine. Proponents of liothyronine argue that the ratio of T3 and T4 hormones is substantially altered on T4 monotherapy and therefore both hormones may be needed for optimal health. This remains controversial as clinical trials have not demonstrated superiority of combination therapy (levothyroxine and liothyronine) over levothyroxine monotherapy. There is now a pressing need for further studies and in particular randomized controlled trials in this area. To help design and facilitate dedicated trials and better understand thyroid hormone replacement, this review summarizes the evidence where there is established knowledge and agreement (knowns) and areas where research is lacking (unknowns). Agreements include the extent of dissatisfaction with levothyroxine monotherapy, biases in testing for hypothyroidism and prescribing levothyroxine, as well as variable thresholds for prescribing levothyroxine and challenges in liothyronine dosing. The review will also highlight and summarize the unknowns including the long-term safety profile of liothyronine, and potential biomarkers to identify individuals who might benefit most from combination therapy.

Short-Term Time Trends in Prescribing Therapy for Hypothyroidism: Results of a Survey of American Thyroid Association Members

Objective: Hypothyroid patients frequently request specific therapies from their physicians. Combination therapy is vigorously discussed at professional meetings. We wished to determine if physician prescribing patterns for hypothyroidism changed during 2017 after specific educational events. Methods: A survey addressing treatment of hypothyroidism was emailed to American Thyroid Association (ATA) members on three occasions in 2017. The Spring emails were sent prior to a satellite symposium addressing hypothyroidism, and prior to the annual Endocrine Society and ATA meetings; the December emails were sent after these events. Physicians were presented with thirteen theoretical patients and chose from 6 therapeutic options, including levothyroxine, synthetic combination therapy, thyroid extract, and liothyronine monotherapy. The patient scenarios successively incorporated factors potentially providing reasons for considering combination therapy. Multivariate repeated measures logistic regression analyses first examined effects of physician characteristics on prescribing the various therapies. Then, analyses also incorporated timing, by comparing prescribing patterns in February, March, and December. Results: In analyses of prescribing levothyroxine monotherapy vs. any T3 therapy, there was a trend of borderline significance (p = 0.053) for T3 therapy to be prescribed more in December compared with February-March combined. When multivariate analyses were performed controlling for time and physician characteristics, choice of therapy was only significantly affected by country of practice (OR 1.7, CI 1.3-2.2). Physician choice of therapies was also examined for the options of continuing (1) levothyroxine, vs. (2) increasing levothyroxine, (3) adding liothyronine either with or without levothyroxine reduction, or (4) replacing levothyroxine with desiccated thyroid extract or liothyronine. When multivariate analyses incorporating time and physician characteristics were performed, respondents in December (OR 1.5, CI 1.0-2.3) and those practicing in North America (OR 1.8, CI 1.2-2.6) were more likely to prescribe liothyronine. Conclusions: This survey shows that although current North American guidelines do not recommend combination therapy, such therapy is being prescribed more over time and is also more commonly prescribed in North America. It is possible our guidelines are failing to incorporate evidence that physicians are considering when prescribing combination therapy. Such evidence could include data about patient preferences, and this needs to be a focus of future studies.

Effects of Long-Term Combination LT4 and LT3 Therapy for Improving Hypothyroidism and Overall Quality of Life

Guidelines from the American Thyroid Association and the American Association of Clinical Endocrinologists suggest monitoring thyroid-stimulating hormone and serum-free thyroxine to make clinical decisions for starting and monitoring therapy with their mainstay treatment of levothyroxine monotherapy. Although this monotherapy provides adequate control of symptoms for the majority of the population, a strong subset of the population continues to complain of hypothyroidism despite normal thyroid-stimulating hormone and serum-free thyroxine levels. Combination levothyroxine and liothyronine therapy to improve symptoms of hypothyroidism has been a topic of interest for several decades, but the data have been mixed. This study provides insight into the effects of combination therapy because there is no reported retrospective or prospective study in the literature.

Supplemental digital content is available in the text.

Objectives

Hypothyroidism results in decreased mood and neurocognition, weight gain, fatigue, and many other undesirable symptoms. The American Association of Clinical Endocrinologists, the American Thyroid Association (ATA), and The Endocrine Society recommend levothyroxine (LT4) monotherapy as the treatment for hypothyroidism; however, after years of monotherapy, some patients continue to experience impaired quality of life. Combination LT4 and synthetic liothyronine (LT3) therapy or the use of desiccated thyroid extract (DTE), has not been suggested for this indication based on short-duration studies with no significant benefits. Our first observational study examined the role of combination therapy for 6 years in improving quality of life in a subset of a hypothyroid population without adverse effects and cardiac mortality.

Methods

An observational retrospective study examining patients prescribed thyroid replacements with serum triiodothyronine (FT3), LT4 with LT3 (synthetic therapy) or DTE (natural therapy), compared with LT4 alone in the United States from 2010 to 2016. Thyroid-stimulating hormone (TSH), serum thyroxine (FT4), and FT3 levels were documented for each patient in addition to any admissions of myxedema coma, thyrotoxicosis, or cardiovascular complications, such as arrhythmias, atrial fibrillation, and mortality. At the conclusion of the study, a cross-sectional interview assessed quality of life for each combination therapy through the Medical Outcomes Study Short Form-20 questionnaire.

Results

Compared with patients taking only LT4, 89.47% using synthetic therapy had therapeutic TSH (P < 0.05). Similarly, 96.49% using natural therapy had therapeutic TSH (P < 0.05). Less than 5% of patients had supratherapeutic FT3. None of the patients who had abnormally low TSH or elevated FT3 or FT4 levels had hospitalizations for arrhythmias or thyrotoxicosis. On the Medical Outcomes Study Short Form-20 questionnaire, >92% answered feeling “excellent, very good, or good” when questioned about their health while undergoing thyroid replacement compared with levothyroxine alone.

Conclusions

This is the only retrospective study reported to use long-term (mean 27 months) thyroid replacements with combination therapy and to compare between the two forms of therapy: synthetic and natural. For patients undergoing either therapy, we did not identify additional risks of atrial fibrillation, cardiovascular disease, or mortality in patients of all ages with hypothyroidism.

Levothyroxine/Liothyronine Combination Therapy and Quality of Life: Is It All about Weight Loss?

OBJECTIVES

According to one hypothesis, the popularity of levothyroxine (L-T₄)/liothyronine (L-T₃) combination therapy relates to weight loss. The purpose of this study was to detect a possible correlation between thyroid-related quality of life (QoL) and weight loss in hypothyroid patients switched from L-T₄ monotherapy to L-T₄/L-T₃ combination therapy.

METHODS

In an open-label cohort study, all hypothyroid patients referred to the University Hospital endocrine clinic due to persistent symptoms despite adequate L-T₄ monotherapy (without other explanations for the symptoms) were switched from L-T₄ monotherapy to L-T₄/ L-T₃ combination therapy at a ratio of approximately 17/1. At baseline and after 3 months of treatment we measured: QoL by the Thyroid Patient-Reported Outcome (ThyPRO-39) questionnaire, thyroid hormones, body weight, body composition by a DEXA-scan, and cognitive function by evaluating participants' reaction time as well as working memory by the California Computerized Assessment Package (CalCAP®). QoL was re-evaluated after 12 months.

RESULTS

Twenty-three patients participated (91% women, median age 47 years). The ThyPRO-39 composite score decreased from a median of 54 (quartiles: 34, 74) to 15 (11, 28) after 3 months (p < 0.0001), and 20 (14, 26) after 12 months, indicating a better QoL. There was no change in body weight, and no correlations between QoL and weight. There was a slight improvement in cognitive function, whereas body composition, heart rate, and serum TSH did not change.

CONCLUSION

Our study on hypothyroid patients switched from L-T₄ monotherapy to L-T₄/L-T₃ combination therapy showed a substantial improvement in QoL measured by the ThyPRO-39. This improvement could not be explained by weight loss.

Lessons from Randomised Clinical Trials for Triiodothyronine Treatment of Hypothyroidism: Have They Achieved Their Objectives?

Randomised controlled trials are deemed to be the strongest class of evidence in evidence-based medicine. Failure of trials to prove superiority of T3/T4 combination therapy over standard LT4 monotherapy has greatly influenced guidelines, while not resolving the ongoing debate. Novel studies have recently produced more evidence from the examination of homeostatic equilibria in humans and experimental treatment protocols in animals. This has exacerbated a serious disagreement with evidence from the clinical trials. We contrasted the weight of statistical evidence against strong physiological counterarguments. Revisiting this controversy, we identify areas of improvement for trial design related to validation and sensitivity of QoL instruments, patient selection, statistical power, collider stratification bias, and response heterogeneity to treatment. Given the high individuality expressed by thyroid hormones, their interrelationships, and shifted comfort zones, the response to LT4 treatment produces a statistical amalgamation bias (Simpson's paradox), which has a key influence on interpretation. In addition to drug efficacy, as tested by RCTs, efficiency in clinical practice and safety profiles requires reevaluation. Accordingly, results from RCTs remain ambiguous and should therefore not prevail over physiologically based counterarguments. In giving more weight to other forms of valid evidence which contradict key assumptions of historic trials, current treatment options should remain open and rely on personalised biochemical treatment targets. Optimal treatment choices should be guided by strict requirements of organizations such as the FDA, demanding treatment effects to be estimated under actual conditions of use. Various improvements in design and analysis are recommended for future randomised controlled T3/T4 combination trials.

Concurrent TSHR mutations and DIO2 T92A polymorphism result in abnormal thyroid hormone metabolism

Deiodinase 2 (DIO2) plays an important role in thyroid hormone metabolism and its regulation. However, molecular mechanism that regulates DIO2 activity remains unclear; only mutaions in selenocysteine insertion sequence binding protein 2 and selenocysteine tranfer RNA (tRNA[Ser]Sec) are reported to result in decreased DIO2 activity. Two patients with clinical evidence of abnormal thyroid hormone metabolism were identified and found to have TSHR mutations as well as DIO2 T92A single nucleotide polymorphism (SNP). Primary-cultured fibroblasts from one patient present a high level of basal DIO2 enzymatic activity, possibly due to compensation by augmented DIO2 expression. However, this high enzymatic active state yet fails to respond to accelerating TSH. Consequently, TSHR mutations along with DIO2 T92A SNP ("double hit") may lead to a significant reduction in DIO2 activity stimulated by TSH, and thereby may have clinical relevance in a select population of hypothyroidism patients who might benefit from a T3/T4 combination therapy.

An Online Survey of Hypothyroid Patients Demonstrates Prominent Dissatisfaction

BACKGROUND

Approximately 15% more patients taking levothyroxine (LT4) report impaired quality of life compared to controls. This could be explained by additional diagnoses independently affecting quality of life and complicating assignment of causation. This study sought to investigate the underpinnings of reduced quality of life in hypothyroid patients and to provide data for discussion at a symposium addressing hypothyroidism.

METHODS

An online survey for hypothyroid patients was posted on the American Thyroid Association Web site and forwarded to multiple groups. Respondents were asked to rank satisfaction with their treatment for hypothyroidism and their treating physician. They also ranked their perception regarding physician knowledge about hypothyroidism treatments, need for new treatments, and life impact of hypothyroidism on a scale of 1-10. Respondents reported the therapy they were taking, categorized as LT4, LT4 and liothyronine (LT4 + LT3), or desiccated thyroid extract (DTE). They also reported sex, age, cause of hypothyroidism, duration of treatment, additional diagnoses, and prevalence of symptoms.

RESULTS

A total of 12,146 individuals completed the survey. The overall degree of satisfaction was 5 (interquartile range [IQR] = 3-8). Among respondents without self-reported depression, stressors, or medical conditions (n = 3670), individuals taking DTE reported a higher median treatment satisfaction of 7 (IQR = 5-9) compared to other treatments. At the same time, the LT4 treatment group exhibited the lowest satisfaction of 5 (IQR = 3-7), and for the LT4 + LT3 treatment group, satisfaction was 6 (IQR = 3-8). Respondents taking DTE were also less likely to report problems with weight management, fatigue/energy levels, mood, and memory compared to those taking LT4 or LT4 + LT3.

CONCLUSIONS

A subset of patients with hypothyroidism are not satisfied with their current therapy or their physicians. Higher satisfaction with both treatment and physicians is reported by those patients on DTE. While the study design does not provide a mechanistic explanation for this observation, future studies should investigate whether preference for DTE is related to triiodothyronine levels or other unidentified causes.

Over- and Under-Treatment of Hypothyroidism Is Associated with Excess Mortality: A Register-Based Cohort Study

OBJECTIVE

This study investigated the association between hypothyroidism and mortality in both treated and untreated hypothyroid patients, and the consequences of over- and under-treatment with respect to mortality.

PATIENTS AND METHODS

This was a register-based cohort study of 235,168 individuals who had at least one serum thyrotropin (TSH) during 1995-2011 (median follow-up 7.2 years). Hypothyroidism was defined as at least two measurements of TSH >4.0 mIU/L within a half year spaced by at least 14 days, or one measurement of TSH >4.0 mIU/L and two filled prescriptions of levothyroxine the following year. All-cause mortality rates were calculated using multivariable Cox regression analysis adjusted for age, sex, and comorbidities using the Charlson Comorbidity Index.

RESULTS

Mortality was increased in untreated hypothyroid individuals (n = 673; hazard ratio [HR] = 1.46 [confidence interval (CI) 1.26-1.69]; p < 0.001) compared to euthyroid controls. Results remained significant even when subdividing according to mild (TSH >4.0 mIU/L and ≤10 mIU/L; p < 0.001) and marked hypothyroidism (TSH >10 mIU/L; p = 0.002). Mortality was increased in both treated and untreated hypothyroid individuals for each six months a patient had increased TSH (HR = 1.05 [CI 1.02-1.07], p < 0.0001, and HR = 1.05 [CI 1.02-1.07], p = 0.0009, respectively). In patients who received levothyroxine, the HR for mortality increased by a factor 1.18 ([CI 1.15-1.21]; p < 0.0001) for each six months a patient exhibited decreased TSH. This finding was essentially unchanged after stratification by disease severity (mild or marked hypothyroidism) and age (older and younger than 65 years).

CONCLUSIONS

Mortality was increased in untreated but not in treated hypothyroid individuals, independently of age and severity of hypothyroidism. Duration of decreased TSH in treated individuals had a greater impact on mortality than did duration of elevated TSH. These results stress the need for close monitoring of treatment in individuals receiving thyroid hormone replacement therapy.

Management of hypothyroidism with combination thyroxine (T4) and triiodothyronine (T3) hormone replacement in clinical practice: a review of suggested guidance

Background

Whilst trials of combination levothyroxine/liothyronine therapy versus levothyroxine monotherapy for thyroid hormone replacement have not shown any superiority, there remains a small subset of patients who do not feel well on monotherapy. Whilst current guidelines do not suggest routine use of combination therapy they do acknowledge a trial in such patients may be appropriate. It appears that use of combination therapy and dessicated thyroid extract is not uncommon but often being used by non-specialists and not adequately monitored. This review aims to provide practical advice on selecting patients, determining dose and monitoring of such a trial.

Main body

It is important to select the correct patient for a trial so as to not delay diagnosis or potentially worsen an undiagnosed condition. An appropriate starting dose may be calculated but accuracy is limited by available formulations and cost. Monitoring of thyroid function, benefits and adverse effects are vital in the trial setting given lack of evidence of safe long term use. Also important is that patients understand set up of the trial, potential risks involved and give consent.

Conclusion

Whilst evidence is lacking on whether a small group of patients may benefit from combination therapy a trial may be indicated in those who remain symptomatic despite adequate levothyroxine monotherapy. This should be undertaken by clinicians experienced in the field with appropriate monitoring for adverse outcomes in both short and long term.

THERAPY OF ENDOCRINE DISEASE: T4 + T3 combination therapy: is there a true effect?

About 5%-10% of hypothyroid patients on T4 replacement therapy have persistent symptoms, despite normal TSH levels. It was hoped that T4 + T3 combination therapy might provide better outcomes, but that was not observed according to a meta-analysis of 11 randomized clinical trials comparing T4 monotherapy with T4 + T3 combination therapy. However, the issue is still subject of much research because normal thyroid function tests in serum may not necessarily indicate an euthyroid state in all peripheral tissues. This review evaluates recent developments in the field of T4 + T3 combination therapy. T4 monotherapy is associated with higher serum FT4 levels than in healthy subjects, and subnormal serum FT3 and FT3/FT4 ratios are observed in about 15% and 30% respectively. T4 + T3 combination therapy may mimic more closely thyroid function tests of healthy subjects, but it has not been demonstrated that relatively low serum FT3 or FT3/FT4 ratios are linked to persistent symptoms. One study reports polymorphism Thr92Ala in DIO2 is related to lower serum FT3 levels after thyroidectomy, and that the D2-Ala mutant reduces T4 to T3 conversion in cell cultures. Peripheral tissue function tests such as serum cholesterol reflect thyroid hormone action in target tissues. Using such biochemical markers, patients who had a normal serum TSH during postoperative T4 monotherapy, were mildly hypothyroid, whereas those with a TSH 0.03-≤0.3 mU/L were closest to euthyroidism. Peripheral tissue function tests suggest euthyroidism more often in patients randomized to T4 + T3 rather than that to T4. Preference for T4 + T3 combination over T4 monotherapy was dose-dependently related to the presence of two polymorphisms in MCT10 and DIO2 in one small study. It is not known if persistent symptoms during T4 monotherapy disappear by switching to T4 + T3 combination therapy. The number of patients on T4 + T3 therapy has multiplied in the last decade, likely induced by indiscriminate statements on the internet. Patients are sometimes not just asking but rather demanding this treatment modality. It creates tensions between patients and physicians. Only continued research will answer the question whether or not T4 + T3 combination therapy has true benefits in some patients.

Neither Baseline nor Changes in Serum Triiodothyronine during Levothyroxine/Liothyronine Combination Therapy Predict a Positive Response to This Treatment Modality in Hypothyroid Patients with Persistent Symptoms

BACKGROUND

Despite biochemical euthyroidism, some levothyroxine (L-T₄)-treated hypothyroid patients report persisting symptoms and some of these patients are tentatively treated with a combination of L-T₄ and liothyronine (L-T₃). Combination therapy and the appropriate choice of blood tests to monitor treatment are highly debated among specialists and patients.

AIM

To evaluate whether measuring serum triiodothyronine (S-T₃) at baseline or during combination therapy can be used as an indicator of a positive effect from L-T₄/L-T₃ combination therapy.

MATERIALS AND METHODS

Observational retrospective study of patients (n = 42) with persisting symptoms of hypothyroidism despite L-T₄ therapy who had normal TSH levels and did not have any comorbidities that could explain their symptoms. All were then treated with L-T₄/L-T₃ combination therapy at a dose ratio of 17/1 according to European Thyroid Association guidelines. Based on patient-reported outcome, they were divided into responders and nonresponders.

RESULTS

Five patients were lost to follow-up and thus excluded. At the 3-month follow-up, 11 were classified as nonresponders and 26 as responders. At 12 months these figures had changed to 13 (35%) and 24 (65%), respectively. When comparing responders versus nonresponders, no differences were seen at baseline or during follow-up in S-T₃ and in free T₃ estimates. Further, logistic regression showed no correlation between S-T₃ and free T₃ estimates and responder/nonresponder status.

CONCLUSION

Our data indicate that serum T₃ measurements are not suitable to predict which patient will benefit from L-T₄/L-T₃ combination therapy, and treatment response cannot be followed by repeated T₃ measurements either.