Type and extent of somatic morbidity before and after the diagnosis of hypothyroidism. a nationwide register study

Thyroid Hormones and Diabetes in Euthyroid Hispanic/Latino Adults of Diverse Backgrounds: HCHS/SOL

Context

Previous studies have demonstrated associations of endogenous thyroid hormones with diabetes; less is known about stages of diabetes development at which they are operative, mechanisms of associations, and the role of the hypothalamic-pituitary-thyroid axis.

Objective

This study examined associations of thyroid hormones with incident prediabetes and diabetes and with changes in glycemic traits in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL), the largest cohort of Hispanic/Latino adults with diverse backgrounds in the United States.

Methods

The study includes 592 postmenopausal euthyroid women and 868 euthyroid men aged 45 to 74 years without diabetes at baseline participating in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL). Baseline hormones included thyrotropin (TSH), free thyroxine (FT4), total triiodothyronine (T3), and indices calculated from thyroid hormones evaluating pituitary sensitivity to thyroid hormone. Transitions to diabetes and prediabetes, and changes in glycemic traits determined at the 6-year follow-up visit, were examined using multivariable Poisson and linear regressions.

Results

Among women, T3 (incident rate ratio [IRR] = 1.65; 95% CI, 1.22-2.24; P = .001) and TSH (IRR = 2.09; 95% CI, 1.01-4.33; P = .047) were positively, while FT4 (IRR = 0.59; 95% CI, 0.39-0.88; P = .011) was inversely, associated with transition from prediabetes to diabetes. Among men, the T3/FT4 ratio was positively associated with transition from normoglycemia to prediabetes but not from prediabetes to diabetes. Indices measuring sensitivity of the pituitary to thyroid hormone suggested increased sensitivity in men who transitioned from prediabetes to diabetes.

Conclusion

Positive associations in women of T3 and TSH and inverse associations of FT4, as well as inverse associations of thyroid indices in men with transition from prediabetes to diabetes, but not from normoglycemia to diabetes, suggest decreased pituitary sensitivity to thyroid hormones in women and increased sensitivity in men later in the development of diabetes.

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.

The effect of hypothyroidism on the risk of diabetes and its microvascular complications: a Mendelian randomization study

Context

Several observational studies have found that hypothyroidism is associated with diabetes and its microvascular complications. However, the cause and effect have not been clarified.

Objective

The aim of the study was to examine the causality of such associations by a Mendelian randomization study.

Methods

Two-sample Mendelian randomization analysis was conducted to investigate the associations. Summary statistics for hypothyroidism were from the UK Biobank, and diabetes and its microvascular complications were from the largest available genome-wide association studies. MR-Egger, weighted median, inverse variance weighted, simple mode and weighted mode were used to examine the causal associations, and several sensitivity analyses were used to assess pleiotropy.

Results

Inverse variance weighted estimates suggested that hypothyroidism was associated with type 1 diabetes and type 1 diabetes with renal complications (β= 9.059926, se= 1.762903, P = 2.76E-07 and β= 10.18375, se= 2.021879, P = 4.73E-07, respectively) but not type 2 diabetes and type 2 diabetes with renal complications. In addition, hypothyroidism was positively associated with severe nonproliferative diabetic retinopathy and proliferative diabetic retinopathy (β= 8.427943, se= 2.142493, P = 8.36E-05 and β= 3.100939, se= 0.74956, P=3.52E-05, respectively).

Conclusions

The study identified the causal roles of hypothyroidism in diabetes and its microvascular complications. Hypothyroidism can lead to type 1 diabetes, type 1 diabetes with renal complications, severe nonproliferative diabetic retinopathy and proliferative diabetic retinopathy.

Hypothyroid women have persistently higher oxidative stress compared to healthy controls

Objective

Some studies suggest that hypothyroidism is associated with increased oxidative stress. Urinary excretion of 8-oxo-7,8-dihydroguanosine (8-oxoGuo) and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) represents whole-body RNA and DNA oxidation, respectively. These biomarkers have only been explored sparsely in patients with thyroid disorders.

Methods

In 45 Danish women with newly diagnosed hypothyroidism, we compared 8-oxoGuo and 8-oxodG before or shortly after initiating levothyroxine with the excretion rates at euthyroidism. We also compared the excretion of 8-oxoGuo and 8-oxodG in the patients after restored euthyroidism with 18 healthy control subjects.

Results

Compared with baseline, none of the biomarkers changed significantly in the patients after becoming euthyroid. The geometric mean of 8-oxoGuo was 1.63 (95% CI: 1.49-1.78) nmol/mmol creatinine at baseline and 1.67 nmol/mmol at euthyroidism (95% CI: 1.53-1.83) (P = 0.39), while that of 8-oxodG was 1.28 nmol/mmol creatinine at baseline (95% CI: 1.14-1.44) and 1.32 nmol/mmol at euthyroidism (95% CI: 1.18-1.48), respectively (P = 0.47). The relative mean differences were 0.97 (95% CI: 0.91-1.04) for 8-oxoGuo and 0.97 (95% CI: 0.88-1.06) for 8-oxodG. At baseline, multiple linear regression revealed a positive association between free thyroxine and both biomarkers (8-oxoGuo, P < 0.001; 8-oxodG, P = 0.04). Furthermore, 8-oxoGuo was positively associated with age (P = 0.04) and negatively associated with thyrotropin (P = 0.02). In the control group, the geometric mean of 8-oxoGuo was 1.23 nmol/mmol creatinine (95% CI: 1.07-1.42), while that of 8-oxodG was 1.04 nmol/mmol creatinine (95% CI: 0.88-1.23). Thus, compared with control subjects, euthyroid patients showed a significantly higher level of both 8-oxoGuo (P < 0.001) and 8-oxodG (P = 0.03).

Conclusion

In hypothyroid women, no significant effect of levothyroxine treatment on the oxidative stress biomarkers 8-oxoGuo and 8-oxodG could be demonstrated. However, the excretion of these biomarkers was significantly higher than in healthy controls.

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.

Association of urinary iodine concentration with prediabetes/diabetes in adults: Analysis of the NHANES 2005-2016

BACKGROUND & AIMS

Iodine is required for synthesizing thyroid hormones and regulating human metabolism. Iodine deficiency can lead to thyroid function abnormalities, which are closely associated with disturbances in glucose-insulin homeostasis. Research on the relationship between iodine and diabetes/prediabetes in adults was sparse and inconsistent. We assessed trends in urinary iodine concentration (UIC) and diabetes/prediabetes prevalence and focused on the association between iodine and diabetes/prediabetes among U.S. adults.

METHODS

We analyzed the National Health and Nutrition Examination Survey (NHANES) data from the 2005-2016 cycles. Linear regression was employed to evaluate UIC and prediabetes/diabetes prevalence trends over time. Both multiple logistic regression and restricted cubic splines (RCS) were performed to evaluate the association of UIC with diabetes/prediabetes.

RESULTS

A distinctly declining trend in median UIC and a significant increase in diabetes prevalence in U.S. adults from 2005 to 2016 were observed. The fourth quartile of UIC was associated with a 30% lower risk for prediabetes, compared with the first quartile (OR=0.70, 95% CI: 0.56-0.86, P_trend=0.001). However, UIC was not significantly associated with the prevalence of diabetes. The RCS model suggested a significant nonlinear relationship between UIC and the risk of diabetes (P for nonlinearity =0.0147). Stratification analysis showed that the negative associations of UIC with the risk of prediabetes were more pronounced in participants who were men, aged 46-65, overweight, light alcohol drinkers, and nonactive smokers.

CONCLUSIONS

Overall, the adults' median UIC in the U.S. population was a declining trend. However, diabetes prevalence increased significantly from 2005 to 2016. Higher UIC was associated with a lower risk of prediabetes.

The enigma of persistent symptoms in hypothyroid patients treated with levothyroxine: A narrative review

A significant minority of patients with hypothyroidism report persistent symptoms despite achieving normal thyroid biochemistry after levothyroxine (L-T4) replacement. Four principal lines of thinking, which are not mutually exclusive, may explain this enigma. The 'low tissue liothyronine hypothesis' emphasizes the potential imperfections of L-T4 replacement therapy that may lead to hypothyroidism in some tissues such as the brain, while others (eg hypothalamus) are euthyroid. The 'Somatic Symptom and Related Disorders hypothesis' draws attention to an incidental coexistence of a diagnosis of Somatic Symptom and Related Disorders in patients with treated hypothyroidism. The 'autoimmune neuroinflammation hypothesis' highlights the potential consequences of inflammatory mediators due to thyroid autoimmunity (the commonest cause of hypothyroidism) on the brain. The 'comorbidities and psychosocial hypothesis' implicates a variety of physical and psychosocial factors that have been noted to be associated with a diagnosis of hypothyroidism, which may be primarily the cause of persistent complaints. Over the past twenty years, a great deal of time and effort has been expended pursuing the 'low tissue liothyronine hypothesis', which has failed to yield results that translate to patient benefits. This has skewed the balance in clinical practice, in favour of pursuing answers relating to L-T4 and liothyronine combination treatment, while the alternative explanations have been downplayed and potentially useful interventions have been given insufficient attention.

The association of diabetes, subclinical hypothyroidism and carotid intima-media thickness: results from the Brazilian Longitudinal Study of Adult Health (ELSA-Brazil)

INTRODUCTION

The association of diabetes with subclinical thyroid diseases may increase the risk of cardiovascular diseases. We analyzed the association of subclinical hypothyroidism, diabetes, and both diseases with carotid Intima-Media Thickness (cIMT) as a surrogate maker for early cardiovascular disease in the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil).

METHODS

Cross-sectional analysis with data from the 3^rd visit (2017‒2019). Linear regression models were used to evaluate the association of subclinical hypothyroidism, diabetes and of both diseases with a cIMT presented as Beta (95% Confidence Interval ‒ 95% CI) without adjustment, with adjustment for sociodemographic variables (Model 1) and multivariable adjustment (Model 1 more cardiovascular risk factors). We also used logistic regression models to analyze the Odds Ratio (OR) and 95% CI for the association of both diseases using cIMT > P75%.

RESULTS

After the exclusion of patients with previous cardiovascular disease, 5,077 participants with no diseases, 1578 with diabetes, 662 with subclinical hypothyroidism, and 234 with both diseases were included in the analysis. Linear regression models showed an association of cIMT with only diabetes (β = 0.019; 95% CI 0.012 to 0.027; p < 0.0001) and subclinical hypothyroidism more diabetes (β = 0.03; 95% CI 0.010‒0.047, p < 0.0001). The logistic regression model reported an association between diabetes and CIMT higher than P75% (OR = 1.49, 95% CI 1.30‒1.71). No interaction between diabetes and subclinical hypothyroidism was detected using cIMT respectively as a continuous (p = 0.29) or as a categorical variable (p = 0.92).

DISCUSSION

Diabetes was associated with higher cIMT values. However, no additive effect of subclinical hypothyroidism associated with diabetes over cIMT was detected.

Prevalencia de diabetes en personas con disfunción tiroidea

OBJECTIVE

To describe the prevalence and relative risk of diabetes in the population with hypothyroidism and hyperthyroidism.

METHODS

A retrospective study was carried out using the Primary Care Clinical Database (BDCAP) of the Ministry of Health. Relative risks (OR) and their 95% confidence intervals (CI) were calculated for type1 (T1D) and type2 (T2D) diabetes.

RESULTS

In the group of 2,596,041 hypothyroid patients, we found an OR of 1.77 (95%CI: 1.75-1.80) for T1D, and 1.77 (95%CI: 1.76-1.78) for T2D. This elevated risk was observed in both men and women. Hypothyroid people over 65years of age had a near neutral risk of T1D (0.96 [95%CI: 0.94-0.99]) and T2D (0.99 [95%CI: 0.98-0.99]). Hypothyroid patients receiving replacement therapy showed a higher risk of T1D (1.32 [95%CI: 1.28-1.36]) and T2D (1.23 [95%CI: 1.22-1.24]) compared to untreated hypothyroid patients. In the group of 418,772 people with hyperthyroidism, an increased risk of T1D (1.66 [95%CI: 1.60-1.72]) and T2D (1.71 [95%CI: 1.70-1.73]) was also noticed. This risk was observed in both sexes. Those over 65years of age did not present a high risk of T1D (0.89 [95%CI: 0.83-0.95]) and their risk of T2D was close to neutrality (1.03 [95%CI: 1.02-1.05]). Hyperthyroid patients treated with antithyroid agents had a higher risk of T1D (1.26 [95%CI: 1.14-1.40]) and T2D (1.32 [95%CI: 1.28-1.36]) than those without therapy.

CONCLUSION

People registered in BDCAP of both sexes, under 65years of age, with thyroid dysfunction have an increased risk of suffering from diabetes, especially those on thyroid medication.

Hypothyroidism has a protective causal association with hepatocellular carcinoma: A two-sample Mendelian randomization study

Objective

Observational studies suggest an association between hypothyroidism and the risk of hepatocellular carcinoma (HCC), but the causality and direction of these effects are still inconclusive. We aim to test whether hypothyroidism is causally associated with the risk of HCC by using Mendelian randomization (MR) analysis.

Methods

Single-nucleotide polymorphisms (SNPs) associated with hypothyroidism were screened via a genome-wide association study (GWAS) on 337,159 individuals of European descent (16,376 cases and 320,783 controls). The SNPs associated with thyroid-stimulating hormone (TSH) and free thyroxine (FT4) were selected from a GWAS of 72,167 individuals of European descent. Summary-level data for HCC (168 cases and 372,016 controls) were extracted from UK Biobank. An inverse-variance-weighted (IVW) method was used as the primary MR analysis. Sensitivity analyses were examined via MR-Egger regression, heterogeneity test, pleiotropy test, and leave-one-out sensitivity test. The assumption that exposure causes outcome was verified using the MR Steiger test.

Results

Two-Sample MR analysis showed inverse associations between genetically predicted hypothyroidism and HCC risk (OR = 0.997, 95% CI, 0.995-0.999; P = 0.016). There were no statistical indications of heterogeneity among instruments (P-het = 0.667). Across five MR methods, genetically predicted hypothyroidism shows a consistent correlation with HCC. The leave-one-out analysis indicated that no single SNP changed the overall estimate (P = 0.016). In addition, the MR Steiger test revealed that hypothyroidism was causal for HCC and not the opposite (P = 0.000). Finally, there was no evidence for a direct causal effect of TSH level and FT4 level on HCC risk.

Conclusion

Our results provide some that genetically determined hypothyroidism decreases the risk of HCC, although the size of the causal estimate is small. Further research is required to comprehend the mechanisms underlying this putative causative association, and follow-up clinical trials need to be conducted to establish whether inducing hypothyroidism could be beneficial for patients who are suffering from HCC. During future treatment of hypothyroidism, close attention to liver function may also be required to prevent a possible increased risk of HCC.

OPG is associated with thyroid nodule development in type 2 diabetes

Background

Thyroid nodule prevalence is increasing lately, especially in diabetes, but the mechanism of which is not clear. In this study, we investigated if osteoprotegerin (OPG) is involved in the pathogenesis of thyroid nodules in diabetes.

Methods

A total of 7568 individuals with detailed information and ultrasound examination results were studied for the prevalence of thyroid nodules. Among them, 1883 were with type 2 diabetes and 5685 were non‐diabetic. Then, 1120 individuals were randomly selected for the measurement of OPG. Diabetic rats were made by feeding a high‐fat‐high‐fructose diet for 28 weeks. Rats fed with a normal diet were as controls. Fresh thyroid tissues were obtained and fixed, dehydrated, and embedded in paraffin for hematoxylin‐eosin staining and observing pathological changes. qPCR and western blot were used to detect OPG expression in rat thyroid tissues.

Results

We found that HbA1c is an independent risk factor for thyroid nodules (Exp [β] = 1.158, p < 0.001). The prevalence of thyroid nodules in type 2 diabetes was higher than that in non‐diabetes (53.9% vs. 46.7%, p < 0.001). Serum OPG levels were significantly elevated in the diabetes group than in the non‐diabetes group (3160.17 pg/ml vs. 2819.39 pg/ml, p < 0.01). The expression of OPG increased significantly in the thyroid tissues of diabetic rats.

Conclusion

Osteoprotegerin may be associated with thyroid nodule development in diabetes.

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.

Thyroid Function and the Risk of Prediabetes and Type 2 Diabetes

CONTEXT

Thyroid hormones are important regulators of glucose metabolism, and studies investigating the association between thyroid function and type 2 diabetes incidence have shown conflicting results.

OBJECTIVE

We aimed to combine the evidence from prospective studies addressing the association between thyroid function and type 2 diabetes risk.

METHODS

We systematically searched in Embase, Medline (Ovid), Web of Science, Cochrane, and Google Scholar for prospective studies assessing the association of thyroid function and incident type 2 diabetes. Data extraction was performed using a standardized protocol by 2 independent reviewers. We assessed study quality using the Newcastle-Ottawa Scale and pooled hazard ratios (HRs) and 95% CI using random-effects models.

RESULTS

From the 4574 publications identified, 7 met our inclusion criteria and were included in the qualitative synthesis. Six publications were included in the meta-analysis. Studies assessed hypothyroidism (6 studies), hyperthyroidism (5 studies), thyrotropin (TSH) in the reference range (4 studies), and free thyroxine (FT4) in the reference range (3 studies) in relation to incident type 2 diabetes. The pooled HR for the risk of type 2 diabetes was 1.26 (95% CI, 1.05-1.52) for hypothyroidism, 1.16 (95% CI, 0.90-1.49) for hyperthyroidism, 1.06 (95% CI, 0.96-1.17) for TSH in the reference range, and 0.95 (95% CI, 0.91-0.98) for FT4 in the reference range.

CONCLUSION

Current evidence suggests an increased type 2 diabetes risk in people with hypothyroidism and lower FT4 levels in the reference range. Further population-based studies are needed to address this association given the limited evidence.

Primary hypothyroidism and quality of life

In the 1970s, treatment with thyroid extract was superseded by levothyroxine, a synthetic L form of tetraiodothyronine. Since then, no major innovation has emerged for the treatment of hypothyroidism. The biochemical definition of subclinical hypothyroidism is a matter of debate. Indiscriminate screening for hypothyroidism has led to overdiagnosis and treatment initiation at lower serum levels of thyroid-stimulating hormone (TSH) than previously. Adverse health effects have been documented in individuals with hypothyroidism or hyperthyroidism, and these adverse effects can affect health-related quality of life (QOL). Levothyroxine substitution improves, but does not always normalize, QOL, especially for individuals with mild hypothyroidism. However, neither studies combining levothyroxine and liothyronine (the synthetic form of tri-iodothyronine) nor the use of desiccated thyroid extract have shown robust improvements in patient satisfaction. Future studies should focus not only on a better understanding of an individual's TSH set point (the innate narrow physiological range of serum concentration of TSH in an individual, before the onset of hypothyroidism) and alternative thyroid hormone combinations and formulations, but also on autoimmunity and comorbidities unrelated to hypothyroidism as drivers of patient dissatisfaction. Attention to the long-term health consequences of hypothyroidism, beyond QOL, and the risks of overtreatment is imperative.

Optimal Thyroid Hormone Replacement

Hypothyroidism is a common endocrinopathy, and levothyroxine is frequently prescribed. Despite the basic tenets of initiating and adjusting levothyroxine being agreed on, there are many nuances and complexities to consistently maintaining euthyroidism. Understanding the impact of patient weight and residual thyroid function on initial levothyroxine dosage and consideration of age, comorbidities, thyrotropin goal, life stage, and quality of life as levothyroxine is adjusted can be challenging and continually evolving. Because levothyroxine is a lifelong medication, it is important to avoid risks from periods of overtreatment or undertreatment. For the subset of patients not restored to baseline health with levothyroxine, causes arising from all aspects of the patient's life (coexistent medical conditions, stressors, lifestyle, psychosocial factors) should be broadly considered. If such factors do not appear to be contributing, and biochemical euthyroidism has been successfully maintained, there may be benefit to a trial of combination therapy with levothyroxine and liothyronine. This is not supported by the majority of randomized clinical trials, but may be supported by other studies providing lower-quality evidence and by animal studies. Given this discrepancy, it is important that any trial of combination therapy be continued only as long as a patient benefit is being enjoyed. Monitoring for adverse effects, particularly in older or frail individuals, is necessary and combination therapy should not be used during pregnancy. A sustained-release liothyronine preparation has completed phase 1 testing and may soon be available for better designed and powered studies assessing whether combination therapy provides superior therapy for hypothyroidism.

Use of thyroid hormones in hypothyroid and euthyroid patients: a THESIS* survey of Belgian specialists *THESIS: treatment of hypothyroidism in Europe by specialists: an international survey

Background

Hypothyroidism is a topic that continues to provoke debate and controversy with regards to specific indications, type of thyroid hormone substitution and efficacy. We investigated the use of thyroid hormones in clinical practice in Belgium, a country where currently only levothyroxine (LT4) tablet formulations are available.

Method

Members of the Belgian Endocrine Society were invited to respond to an online questionnaire. Results were compared with those from other THESIS surveys.

Results

Eighty (50%) of the invited 160 individuals, completed the questionnaire. LT4 was the first treatment of choice for all respondents. As secondary choice, some also prescribed liothyronine (LT3) and LT4 + LT3 combinations (2 and 7 respondents, respectively). Besides hypothyroidism, 34 and 50% of respondents used thyroid hormones for infertile euthyroid TPOAb positive women and the treatment of a growing non-toxic goiter, respectively. Had alternative formulations of LT4 to tablets been available (soft gel or liquid L-T4), 2 out of 80 (2.5%) participants would consider them for patients achieving biochemical euthyroidism but remaining symptomatic. This proportion was higher in case of unexplained poor biochemical control of hypothyroidism (13.5%) and in patients with celiac disease or malabsorption or interfering drugs (10%). In symptomatic euthyroid patients, 20% of respondents would try combined LT4 + LT3 treatment. Psychosocial factors were highlighted as the main contributors to persistent symptoms.

Conclusions

LT4 tablets is the preferred treatment for hypothyroidism in Belgium. A minority of the respondents would try combined LT4 + LT3 in symptomatic but biochemically euthyroid patients. Thyroid hormones are prescribed for euthyroid infertile women with thyroid autoimmunity and patients with non-toxic goiter, a tendency noted in other European countries, despite current evidence of lack of benefit.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13044-022-00121-9.

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

PURPOSE

To investigate current practices of specialists in the use of thyroid hormone preparations in Greece as part of an ongoing international survey, namely THESIS-Treatment of Hypothyroidism in Europe by Specialists: an International Survey.

METHODS

An electronic link leading to an anonymized questionnaire was sent to all (n = 837) members of the Hellenic Endocrine Society.

RESULTS

In total, 501 respondents participated in the survey, though only part of the questionnaire was filled in by some participants. A total of 88.2% were endocrinologists and 57.9% worked in private practice. Levothyroxine (LT4) was the first-line choice (98.6%) for the treatment of hypothyroid patients. In total, 70.2% preferred LT4 soft-gel capsules for patients reporting intolerance to various foods. Soft-gel capsules were the preferred LT4 formulation for patients on generic LT4 and with unexplained poor biochemical control of hypothyroidism (66.3%) or inability to take LT4 fasted and separate from food/drink (68.3%). It was found that 48.4% would never use combined LT4 + LT3. However, 25% would use combination therapy for a short period in patients recovering from protracted hypothyroidism or in patients with normal serum TSH but persistent symptoms. Concerning euthyroid individuals, 31.9% considered treatment with thyroid hormones in infertile females with positive thyroid antibodies and 24.4% in patients with growing goiter. Selenium or iodine supplementation was used occasionally, mostly in patients with coexisting autoimmune thyroiditis.

CONCLUSIONS

LT4 tablets are the treatment of choice for hypothyroidism in Greece. Several conditions may lead to various other practices, some of which deviate from current evidence-based guidelines and need more scrutiny.

Links between Thyroid Disorders and Glucose Homeostasis

Thyroid disorders and diabetes mellitus often coexist and are closely related. Several studies have shown a higher prevalence of thyroid disorders in patients with diabetes mellitus and vice versa. Thyroid hormone affects glucose homeostasis by impacting pancreatic β-cell development and glucose metabolism through several organs such as the liver, gastrointestinal tract, pancreas, adipose tissue, skeletal muscles, and the central nervous system. The present review discusses the effect of thyroid hormone on glucose homeostasis. We also review the relationship between thyroid disease and diabetes mellitus: type 1, type 2, and gestational diabetes, as well as guidelines for screening thyroid function with each disorder. Finally, we provide an overview of the effects of antidiabetic drugs on thyroid hormone and thyroid disorders.

The impact of levothyroxine exposure on delivery outcome in hypothyroid pregnant women (PETAL study): A five-year retrospective cohort study

Background

Hypothyroidism affects 3% of pregnant women, and to date, no studies have addressed the impact levothyroxine-treated hypothyroidism on delivery outcome.

Methods

This retrospective cohort study was conducted among 750 women with a singleton pregnancy who gave birth between 2015 and 2019. Delivery modes were compared between 250 hypothyroid women exposed to levothyroxine and 500 euthyroid control women. The aim of this study was to determine the impact of levothyroxine exposure on delivery outcome.

Results

Multiple logistic regression showed no significant association between exposure to levothyroxine and the overall rate of caesarean delivery (aOR 1.1; 95% CI 0.8 to 1.6). Mean TSH concentrations were significantly higher throughout the pregnancy in hypothyroid women despite levothyroxine treatment. Maternal and neonatal outcomes in both groups were not different.

Conclusion

Hypothyroidism treated with levothyroxine during pregnancy according to local guidelines is not a significant risk factor for caesarean delivery.

[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.

Risk of Diabetes in Patients with Long-Standing Graves' Disease: A Longitudinal Study

BACKGROUND

The detrimental effects of excessive thyroid hormone on glucose metabolism have been widely investigated. However, the risk of diabetes in patients with long-standing hyperthyroidism, especially according to treatment modality, remains uncertain, with few longitudinal studies.

METHODS

The risk of diabetes in patients with Graves' disease treated with antithyroid drugs (ATDs) for longer than the conventional duration (≥2 years) was compared with that in age-and sex-matched controls. The risk was further compared according to subsequent treatment modalities after a 24-month course of ATD: continuation of ATD (ATD group) vs. radioactive iodine ablation (RIA) group.

RESULTS

A total of 4,593 patients were included. Diabetes was diagnosed in 751 (16.3%) patients over a follow-up of 7.3 years. The hazard ratio (HR) for diabetes, after adjusting for various known risk factors, was 1.18 (95% confidence interval [CI], 1.10 to 1.28) in patients with hyperthyroidism. Among the treatment modality groups, the RIA group (n=102) had a higher risk of diabetes than the ATD group (n=4,491) with HR of 1.56 (95% CI, 1.01 to 2.42). Further, the risk of diabetes increased with an increase in the ATD treatment duration (P for trend=0.019).

CONCLUSION

The risk of diabetes was significantly higher in patients with long-standing Graves' disease than in the general population, especially in patients who underwent RIA and prolonged ATD treatment. Special attention to hyperglycemia during follow-up along with effective control of hyperthyroidism may be necessary to reduce the risk of diabetes in these patients.

Real-life practice of thyroid hormone use in hypothyroid and euthyroid patients: a detailed view from the THESIS* questionnaire survey in France

AIM

To describe practices of French physicians regarding thyroid hormone therapy, focusing on available LT4 formulations.

MATERIAL AND METHODS

Members of the French Endocrine Society (FES) and affiliated societies (the Endocrine Tumor Group, French College of Teachers of Endocrinology, Diabetes and Metabolic Diseases and the Union of Endocrinology, Diabetology, Metabolic Diseases and Nutrition Specialists) were invited to participate in an online survey.

RESULTS

534 of the 2,094 persons contacted (25.5%) completed the survey and were included in the analysis. The vast majority (99.4%) reported that levothyroxine (LT4) is the treatment of choice for hypothyroidism. 7.1% and 14.2% of respondents respectively considered liothyronine (LT3) or a combination of LT4 and LT3 for the treatment of hypothyroidism, mainly when symptoms persisted despite achieving normal TSH concentrations with LT4 therapy. For 44% of respondents, thyroid hormone treatment is never indicated in euthyroid patients, while the remainder would consider treating euthyroid patients with a goiter growing over time (40.2%) and/or euthyroid women with positive anti-TPO antibodies and infertility (31.7%). LT4 tablets were the preferred LT4 formulation. A significant proportion of FES members expected no major clinical differences upon changing to formulations such as soft-gel capsules or liquid solutions, even in specific scenarios such as poor biochemical control or suspicion of malabsorption.

CONCLUSION

The treatment of choice for hypothyroidism in France is LT4. LT3-based therapy is considered by some physicians in case of persistent symptoms of hypothyroidism despite normal TSH level. A significant proportion of respondents (66.0%) would consider treating euthyroid patients, contrary to the present state of knowledge. These outdated practices should be addressed by professional bodies such as the FES.

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.

Association between thyroid dysfunction and type 2 diabetes: a meta-analysis of prospective observational studies

BACKGROUND

Diabetes mellitus and thyroid disease are two areas of broad interest in the field of endocrinology and metabolism. Variation of thyroid hormone concentration, even within the normal range, may portend the onset of type 2 diabetes mellitus (T2DM), especially among those with prediabetes. However, current evidence is mixed.

METHODS

Prospective studies which assessed diabetes incidence were identified using a database search of MEDLINE and Embase through May 1, 2021. The Sidik-Jonkman random-effects model and cubic spline model were used to evaluate the associations and dose-response relationships between thyroid function/hormone levels and risk of T2DM and cardiovascular disease (CVD) risk among T2DM patients.

RESULTS

A total of 12 prospective studies were included. We found that high baseline TSH levels were related to a 17% higher risk of T2DM (RR 1.17, 95% CI 1.01, 1.36; I²=78%, P<0.01), compared with normal TSH levels. Low FT3 (RR 1.40, 95% CI 1.09, 1.80; I²=59%, P=0.03) and low FT4 (RR 1.33, 95% CI 1.04, 1.71; I²=62%, P=0.02) levels were significantly associated with risk of T2DM. The cubic spline model indicated a J-shaped relationship with TSH, but inverted-J-shaped relationships with FT3 and FT4. CVD events and all-cause deaths were prospectively evaluated in four studies, but were not associated with abnormal thyroid function.

CONCLUSIONS

Our meta-analysis determined that abnormal thyroid hormone level is associated with an increased risk of T2DM, showing a J-shaped relationship with TSH and inverted-J-shaped relationships with FT3 and FT4.

TRIAL REGISTRATION

Registered number in PROSPERO: CRD42021225695 .

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection and thyroid disease. An update

PURPOSE OF REVIEW

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection is associated with excess morbidity and mortality in patients with hypertension and diabetes but little is known about thyroid diseases. Thus, our goal was to review the literature with respect to: (i) Are patients with underlying hypo- or hyperthyroidism at increased risk of contracting SARS-CoV-2 infection? (ii) do underlying hypo- and hyperthyroidism impact the prognosis of SARS-CoV-2 infection? (iii) does SARS-CoV-2 infection cause de novo thyroid dysfunction?

RECENT FINDINGS

Patients with hypo- or hyperthyroidism do not have an increased risk of contracting SARS-CoV-2, and a diagnosis of hypo- or hyperthyroidism is not associated with a worsened prognosis of SARS-CoV-2 infection. SARS-CoV-2 infection has been associated with subsequent thyrotoxicosis, euthyroid sick syndrome, subacute thyroiditis, and autoimmune thyroid disease.

SUMMARY

These findings suggest that receiving treatment for thyroid dysfunction does not per se impact the patients' risk of acquiring SARS-CoV-2 infection, or the management of those who already contracted it. Additional studies with larger numbers of patients and long-term follow-up are required in order to clarify whether patients with SARS-CoV-2 infection are more or less prone to develop thyroid dysfunction and/or thyroid autoimmunity than patients recovering from other virus infections.

Adolescent Thyroid Disorders and Risk for Type 2 Diabetes in Young Adulthood

CONTEXT

Thyroid hormones play a key role in systemic metabolism, yet the relationship between thyroid dysfunction and risk for type 2 diabetes is unclear.

OBJECTIVE

To assess type 2 diabetes risk in adulthood among adolescents with thyroid disorders.

DESIGN AND SETTING

A nationwide, population-based study of Israeli adolescents who were examined before military recruitment during 1988 to 2007 and were followed until December 31, 2016.

PARTICIPANTS

1 382 560 adolescents (mean age 17.3 years).

INTERVENTIONS

The diagnosis of thyroid disorders was based on recent thyroid function tests. Data were linked to the Israeli National Diabetes Registry. Cox proportional hazard models were applied.

MAIN OUTCOME MEASURES

Type 2 diabetes incidence.

RESULTS

During a mean follow-up of 18.5 years, 1.12% (69 of 6,152) of adolescents with thyroid disorders were diagnosed with type 2 diabetes vs 0.77% of adolescents without thyroid disorders. The hazard ratio (HR) for type 2 diabetes was 2.3 (95% CI, 1.8-2.9) among those with thyroid disorders, after adjustment for sex, birth-year, body mass index, and sociodemographic confounders. The increased diabetes risk was observed in both men and women, with the presence or absence of obesity, and in the absence of other health conditions and was associated with different types of thyroid disorders. It was also similar when the outcome was defined as type 2 diabetes diagnosed at or before the age of 30 years (HR 2.3, 95% CI, 1.5-3.5).

CONCLUSIONS

Thyroid disorders diagnosed in adolescence are a risk factor for early-onset type 2 diabetes in both men and women.

The Effects of Previous Thyroid Disease on the Susceptibility to, Morbidity of, and Mortality Due to COVID-19: A Nationwide Cohort Study in South Korea

This study aimed to investigate the associations of the susceptibility to, morbidity of, and mortality due to coronavirus disease 2019 (COVID-19) with thyroid diseases. Korea National Health Insurance Database Coronavirus disease 2019 (NHID-COVID-19) medical claim code data from 2015 to 2020 were analyzed. A total of 8070 COVID-19 patients and 32,280 matched control participants were evaluated for histories of hypothyroidism, hyperthyroidism, Graves’ disease, thyroiditis, and autoimmune thyroiditis. The relationships of susceptibility to, morbidity of, and mortality due to COVID-19 with hypothyroidism, hyperthyroidism, Graves’ disease, thyroiditis, and autoimmune thyroiditis were analyzed using a conditional logistic regression. Hypothyroidism, hyperthyroidism, Graves’ disease, thyroiditis, and autoimmune thyroiditis were not associated with susceptibility to, morbidity of, or mortality due to COVID-19. Graves’ disease was related to higher odds of mortality due to COVID-19 in the adjusted model but the confidence interval (CI) was wide, probably due to the small number of deaths among patients with Graves’ disease (aOR = 11.43, 95% CI = 1.29–101.22, p = 0.029). Previous histories of hypothyroidism, hyperthyroidism, Graves’ disease, thyroiditis, and autoimmune thyroiditis were not related to susceptibility to COVID-19. In addition, prior histories of thyroid diseases were not related to increased risks of COVID-19-related morbidity and mortality.

Increased risk of dementia in hypothyroidism: A Danish nationwide register-based study

OBJECTIVE

Globally, the prevalence of individuals with dementia is increasing, and identification of risk factors is of paramount interest. Using population-based registers, we evaluated whether hypothyroidism is a risk factor for dementia.

DESIGN

Register-based cohort study.

PATIENTS AND METHODS

Risk of dementia was evaluated in two cohorts. The DNPR cohort comprises 111,565 hypothyroid patients, diagnosed between 1995 and 2012, and 446,260 euthyroid age- and sex-matched individuals (median follow-up 6.2 years). The OPENTHYRO cohort comprises 233,844 individuals with at least one measurement of serum thyrotropin (TSH) between 1995 and 2011, of whom 2,894 had hypothyroidism (median follow-up 7.2 years). Primary outcome was dementia defined as an International Classification of Diseases 10 code, or prescription of medicine for dementia.

RESULTS

In the DNPR cohort, risk of dementia was significantly increased in subjects with hypothyroidism (HR 1.22; 95% CI: 1.17-1.27), which attenuated after adjusting for pre-existing comorbidity (HR 0.82; 95% CI: 0.79-0.86). Stratification of age into ≤56 and >56 years showed an inverse relationship between age and risk of dementia (HR_{≤56 years.} 2.03; 95% CI: 1.62-2.53 and HR_>56 years . 1.00; 95% CI: 0.96-1.05). In the OPENTHYRO cohort, the risk of dementia was significantly increased for each 6 months of elevated TSH (HR 1.12; 95% CI: 1.07-1.16).

CONCLUSIONS

Hypothyroidism is associated with increased risk of dementia. The association is influenced by comorbidity and age. Every 6 months of elevated TSH increased the risk of dementia by 12%, suggesting that also the length of hypothyroidism influences the risk of dementia.

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.

Determining minimal important change for the thyroid-related quality of life questionnaire ThyPRO

OBJECTIVE

ThyPRO is the standard thyroid patient-reported outcome (PRO). The change in scores that patients perceive as important remains to be ascertained. The purpose of this study was to determine values for minimal important change (MIC) for ThyPRO.

METHODS

A total of 435 patients treated for benign thyroid diseases completed ThyPRO at baseline and 6 weeks following treatment initiation. At 6 weeks follow-up, patients also completed Global Rating of Change items. For each 0-100 scale, two MIC values were identified: An MIC for groups, using the receiver operating characteristic (ROC) curve method and an MIC for individual patients, using the Reliable Change Index.

RESULTS

ROC analyses provided group-MIC estimates of 6.3-14.3 (score range 0-100). Evaluation of area under the curve (AUC) supported the robustness for 9 of 14 scales (AUC > 0.7). Reliable Change Index estimates of individual-MIC were 8.0-21.1. For all scales but two, the individual-MIC values were larger than the group-MIC values.

CONCLUSIONS

Interpretability of ThyPRO was improved by the establishment of MIC values, which was 6.3-14.3 for groups and 8.0-21.1 for individuals. Thus, estimates of which changes are clinically relevant, are now available for future studies. We recommend using MIC values found by ROC analyses to evaluate changes in groups of patients, whereas MIC values identified by a dual criterion, including the reliability of changes, should be used for individual patients, for example, to identify individual responders in clinical studies or practice.

New Formulations of Levothyroxine in the Treatment of Hypothyroidism: Trick or Treat?

Background: Levothyroxine (LT4) as a medication is used by up to 5.3% of the adult population. For optimal efficacy, the traditional tablet formulation (LT4tab) requires that patients avoid concomitant ingestion with food, drinks, and certain medications, as well as excellent patient compliance. Some comorbidities influence bioavailability of LT4 and may mandate repeated dose adjustments. Summary: New LT4 formulations (soft gel [LT4soft] and liquid [LT4liq]) containing predissolved LT4 are claimed to improve bioavailability, presumably by facilitating absorption. Thus, these formulations may well be more suitable than LT4tab for patients whose daily requirements are subjected to variations in bioavailability. Here, we review the evidence and indications for use of new LT4 formulations and highlight areas of uncertainty that are worthy of further investigation. While bioequivalence is established for LT4soft and LT4liq administered to healthy volunteers compared with LT4tab in pharmacokinetic (PK) studies, therapeutic equivalence of the new formulations seems to be different in several clinical settings. Some evidence suggests that new formulations of LT4 may mitigate against the strict requirements relating to concomitant ingestion with food, drinks, and certain medications, which apply to traditional LT4 tablets. The principal indication is in selected patients with disease fluctuations and intermittent therapies with interfering medications, where the need for frequent dose adjustments and office visits may be diminished. Whether the use of LT4soft or LT4liq in patients with impaired gastric acid secretion results in better control of hypothyroidism than LT4tab remains unclear. Conclusions: The evidence in favor of using LT4soft and LT4liq in clinical practice over LT4tab is weak, and the underlying putative PK mechanisms unclear. Additional studies to investigate these potential benefits, define the cost-effectiveness, and understand the PK mechanisms involved with new LT4 formulations are needed.

Restoration of euthyroidism in women with Hashimoto's thyroiditis changes bone microarchitecture but not estimated bone strength

PURPOSE

Fracture risk in hypothyroid patients is debated, and since the effects of hypothyroidism on bone microarchitecture and strength are unclarified, we investigated these characteristics by high-resolution peripheral quantitative computed tomography (HR-pQCT).

METHODS

Two approaches were used: a cross-sectional control study, comparing 32 hypothyroid women (mean age; 47 ± 12 years) suffering from Hashimoto's thyroiditis with 32 sex-, age-, and menopause-matched healthy controls; a prospective study, where 27 of the women were reexamined 1 year after restoration of euthyroidism. HR-pQCT of the distal radius and tibia, and dual-energy X-ray absorptiometry (DXA) of the spine and hip were performed. Bone strength was estimated using a finite element analysis (FEA).

RESULTS

Cross-sectional control study: in the radius, total (mean 14.6 ± 29.3% (SD); p = 0.04) and trabecular bone areas (19.8 ± 37.1%, p = 0.04) were higher, and cortical volumetric bone mineral density (vBMD) lower (-2.2 ± 6.5%, p = 0.032) in hypothyroid patients than in controls. All indices of tibia cortical and trabecular vBMD, microarchitecture, and estimated bone strength were similar between groups, as was hip and spine areal BMD (aBMD). Prospective study: in the radius, mean cortical (-0.9 ± 1.8%, p = 0.02) and trabecular (-1.5 ± 4.6%, p = 0.02) vBMD decreased, and cortical porosity increased (18.9 ± 32.7%, p = 0.02). In the tibia, mean total vBMD (-1.1 ± 1.9%, p = 0.01) and cortical vBMD (-0.8 ± 1.4%, p = 0.01) decreased, while cortical porosity (8.2 ± 11.5%, p = 0.002) and trabecular area (0.2 ± 0.6%, p = 0.047) increased. No changes in FEA were detected. Lumbar spine aBMD decreased (-1.3 ± 3.0%, p = 0.04).

CONCLUSIONS

Hypothyroidism was associated with an increased trabecular bone area and a lower mineral density of cortical bone in the radius, as assessed by HR-pQCT. Restoration of euthyroidism mainly increased cortical porosity, while estimated bone strength was unaffected.

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.

Prevalence of Thyroid Dysfunction in a Chinese Population with Different Glucose Intolerance Status: A Community-Based Cross-Sectional Study

AIM

Impaired glucose metabolism and thyroid dysfunction (TD) are the two most common chronic metabolic disorders. This study aimed to investigate the epidemiological characteristics of TD in different status of glucose tolerance in a community-based Chinese population and to understand the association between TD and glucose metabolism.

METHODS

A community-based population study of metabolic disease was conducted from June 2013 to September 2014 in Beijing, China. Residents aged 26-76 years were selected according to gender and age composition using multi-stage stratified random sampling process. All participants underwent serum thyroid function and thyroid-associated antibody tests. The status of glucose tolerance was determined using 75g-oral glucose tolerance test. Chi-square test was used to compare the differences in prevalence. Multivariate logistic regression analysis was used to determine the impact of insulin resistance (IR) on thyroid function.

RESULTS

By analyzing 3986 participants who were included in the survey, the prevalence of type 2 diabetes (T2DM) and pre-diabetes (pre-DM) was 18.59% and 26.79%, respectively. The prevalence of TD was 8.81%, with overt hyperthyroidism accounting for 0.38%; subclinical hyperthyroidism, 1.86%; overt hypothyroidism, 0.70%; and subclinical hypothyroidism, 5.87%. The prevalence of TD increased with gradually deteriorated glucose tolerance (7.63% in those with normal glucose tolerance, 9.27% in pre-DM, and 11.61% in T2DM) in both men and women. Each unit of higher HOMA-IR was associated with 7% higher likelihood of having subclinical hypothyroidism.

CONCLUSION

The coexisting of TD with T2DM and pre-DM is high in this community-based Chinese population, suggesting a close relationship between TD and glucose metabolism.

The Impact of Thyroid Diseases on the Working Life of Patients: A Systematic Review

Thyroid diseases are characterized by a wide range of physical and mental symptoms that can affect biological function, emotional and social life of patients. However, their impact on work functioning is not yet fully understood. Therefore, this review aims to address the way in which thyroid diseases can affect occupational outcomes, i.e., the employment rate, sick leave, working capacity and work income of patients. A systematic review of Pubmed, Scopus and ISI Web of Knowledge databases has been performed. Although it is not possible to extrapolate precise data for benign pathologies, about a third of the survivors of thyroid cancer could be unemployed. Hyperthyroid and hypothyroid patients presented a greater risk of long-term sick leave than controls, depending on the severity of the disease. Hyperthyroidism impaired working ability in about a third of affected patients, particularly in cases complicated by orbitopathy with diplopia. A possible influence of thyroid diseases on various occupational outcomes emerged from our review, however further research seems necessary to understand the relationship between work problems, specific pathological characteristics over time and risk factors in the workplace. This may support a comprehensive, interdisciplinary management of thyroid disorders, with benefits for patients’ personal, social and professional life.

Death by unnatural causes, mainly suicide, is increased in patients with Hashimoto's thyroiditis. A nationwide Danish register study

PURPOSE

Hashimoto's thyroiditis (HT) is associated with excess psychiatric in addition to reduced quality of life. However, little is known about risk of unnatural manners of death in HT. We investigated the risk of death by accidents, suicide, violence/homicide, and unknown causes in patients with HT, compared to a matched control population.

METHODS

Register study covering all adult Danes diagnosed with HT during 1995-2012. In total, 111,565 HT cases were identified and matched for age and sex with four euthyroid controls. The hazard ratios (HR) for mortality were calculated using Cox regression analyses, adjusted for pre-existing morbidity. Median follow-up time was 5.9 years (range 0-17.5).

RESULTS

Compared to controls, HT patients had an increased frequency of death by suicide (0.10% vs 0.07%, p < 0.001) and unknown manners (0.05% vs 0.02%, p < 0.001). There were no significant differences between controls and HT patients in risk of death by accidents (0.36% vs 0.37%, p = 0.384) or violence (0.004% vs 0.005%, p = 0.749). After adjustment for pre-existing somatic and psychiatric morbidity HT patients still had an increased risk of suicide and death by unknown causes, whereas risk of death caused by accidents was reduced.

CONCLUSIONS

Mortality due to suicide and unknown causes, but not accidents and violence, was increased in HT. This indicates that HT may have a significant role in the pathophysiological mechanisms of suicidal behavior. This suggests that physicians caring for HT patients should be vigilant when facing expressions of suicidal ideation or signs and symptoms of self-harm as a first step towards prevention.

Thyroid Dysfunction and Diabetes Mellitus: Two Closely Associated Disorders

Thyroid dysfunction and diabetes mellitus are closely linked. Several studies have documented the increased prevalence of thyroid disorders in patients with diabetes mellitus and vice versa. This review critically discusses the different underlying mechanisms linking type 1 and 2 diabetes and thyroid dysfunction to demonstrate that the association of these two common disorders is unlikely a simple coincidence. We assess the current state of knowledge on the central and peripheral control of thyroid hormone on food intake and glucose and lipid metabolism in target tissues (such as liver, white and brown adipose tissue, pancreatic β cells, and skeletal muscle) to explain the mechanism linking overt and subclinical hypothyroidism to type 2 diabetes and metabolic syndrome. We also elucidate the common susceptibility genes and the pathogenetic mechanisms contributing to the autoimmune mechanism involved in the onset of type 1 diabetes mellitus and autoimmune thyroid disorders. An untreated thyroid dysfunction can impair the metabolic control of diabetic patients, and this association can have important repercussions on the outcome of both of these disorders. Therefore, we offer recommendations for the diagnosis, management, and screening of thyroid disorders in patients with diabetes mellitus, including the treatment of diabetic patients planning a pregnancy. We also discuss the major causes of failure to achieve an optimal management of thyroid dysfunction in diabetic patients and provide recommendations for assessing and treating these disorders during therapy with antidiabetic drugs. An algorithm for a correct approach of these disorders when linked is also provided.

Duration of over- and under-treatment of hypothyroidism is associated with increased cardiovascular risk

Objective To investigate the association between hypothyroidism and cardiovascular disease (CVD) in both treated and untreated hypothyroid patients, and the consequences of over- and under-treatment with respect to cardiovascular risk. Design A registry-based case-control study nested within a population-based cohort of 275 467 individuals with at least one serum thyroid stimulating hormone (TSH) measurement in the period of 1995-2011. Methods Incident cases of CVD were matched with controls according to gender, age and year of birth. Conditional logistic regression analyses were performed to calculate CVD risks associated with exposure to hypothyroidism, with adjustment for 19 pre-existing comorbidities, including cardiovascular disease and diabetes, using the Charlson Comorbidity Index. Results Overall, 20 487 individuals experienced CVD (9.4%, incidence rate 13.1 per 1000 person-years, 95% confidence interval (CI), 13.0-13.3). Risk of CVD was increased in untreated hypothyroidism compared to euthyroidism (odds ratio (OR): 1.83 (95% CI: 1.43-2.35; P < 0.001)). Cardiovascular risk was increased in both treated and untreated hypothyroid individuals per half year of elevated TSH (OR: 1.11 (95% CI: 1.06-1.16; P < 0.001) and OR: 1.15 (95% CI: 1.09-1.23; P = 0.001), respectively). In patients treated with levothyroxine, OR for CVD was 1.12 (95% CI: 1.06-1.18; P < 0.001) for each 6 months of decreased TSH. Conclusion Cardiovascular risk is increased in untreated, but not in treated hypothyroid patients. Among those with treated hypothyroidism, duration of decreased TSH (overtreatment) had a similar impact on cardiovascular risk as duration of elevated TSH (under-treatment), highlighting the importance of initiating treatment and maintaining biochemical euthyroidism in hypothyroid patients in order to reduce the risk of CVD and death.

Sex-Specific Risk of Cardiovascular Disease in Autoimmune Addison Disease-A Population-Based Cohort Study

CONTEXT

Little is known of cardiovascular disease (CVD) in autoimmune Addison disease (AAD). Inadequate glucocorticoid replacement might potentially increase CVD risk.

OBJECTIVE

To examine CVD in AAD in subgroups of ischemic heart disease (IHD) and cerebrovascular disease (CeVD) and investigate the effects of glucocorticoid and mineralocorticoid dosing.

DESIGN, SETTING, AND PATIENTS

In this cohort-control study, we used Swedish health registries from 1964 to 2013 to identify 1500 subjects with AAD and 13,758 matched controls. Incident CVD was analyzed from 2006 to 2013. Adjusted hazard ratios (aHRs) were calculated using Cox proportional hazard models. Glucocorticoid and mineralocorticoid doses were stratified to examine dose-related risks.

RESULTS

During 8807 person-years (PY), 94 events of first CVD (10.7/1000 PY) in patients with AAD occurred compared with 563 events during 80,163 PY (7.0/1000 PY) in controls. IHD was significantly more common in women (aHR, 2.15; 95% CI, 1.49 to 3.10) but not men (aHR, 1.16; 95% CI, 0.75 to 1.78) with AAD compared with controls. No increase in CeVD risk was detected (aHR, 0.88; 95% CI, 0.56 to 1.37, women; aHR, 0.88; 95% CI 0.53 to 1.50, men). CVD was associated with greater glucocorticoid and mineralocorticoid replacement doses in women but not men.

CONCLUSION

The risk of IHD but not CeVD is increased in AAD, especially in women. The risk of CVD independently correlated with greater glucocorticoid and mineralocorticoid replacement doses in women. Our data suggest that close monitoring and early treatment of risk factors for CVD, among women in particular, might be warranted.

Thyroid-stimulating hormone levels in the normal range and incident type 2 diabetes mellitus

AIM

To evaluate the relationship between thyroid-stimulating hormone (TSH) levels within the normal range and the risk of type 2 diabetes mellitus (T2DM) in a cohort of patients at high cardiovascular risk, and to perform a systematic review and meta-analysis of previous studies.

METHODS

We included 5542 patients without T2DM from the prospective Secondary Manifestations of ARTerial disease study with TSH levels between 0.35 and 5.0 mIU/L without anti-thyroid medication or thyroid-hormone replacement therapy. Cox regression was used to investigate the relationship between baseline plasma TSH levels and incident T2DM. MEDLINE, EMBASE, and Cochrane were searched for prospective cohorts assessing TSH and incident T2DM. Hazard ratios (HR) from included prospective cohort studies were pooled using a random-effects model.

RESULTS

In patients at high cardiovascular risk, higher plasma TSH levels in the normal range were not associated [HR 1.07 per mIU/L increase in TSH (95% confidence interval (95% CI) 0.95-1.22)] with an increased risk of T2DM, adjusted for age, sex, smoking, total and HDL cholesterol, and triglycerides. In the meta-analysis involving three prospective cohort studies, including the present study, including 29,791 participants with 1930 incident events, there was no relation between plasma TSH levels in the normal range and incident T2DM [pooled HR 1.06 (95% CI 0.99-1.14)].

CONCLUSION

There is no apparent relation between plasma TSH levels in the normal range and incident T2DM in patients at high cardiovascular risk.

Patients with Benign Thyroid Diseases Experience an Impaired Sex Life

BACKGROUND

This study aimed to characterize the frequency of self-reported thyroid-related impaired sex life in patients with thyroid diseases, to examine its clinical correlates and relationship with overall quality of life (QOL), and to investigate the effect of treatment.

PATIENTS AND METHODS

Two separate patient samples with benign thyroid diseases were investigated: a cross-sectional sample (759 women and 118 men) treated at two Danish university hospital outpatient clinics, in 2007-2008, and a longitudinal sample (358 women and 74 men) undergoing treatment at the abovementioned centers, during 2008-2012, evaluated before and 6 months after therapy. The thyroid-specific QOL questionnaire ThyPRO was used to measure patient-evaluated thyroid-related sex life impairment. Biochemical and clinical variables were analyzed (i.e., age, education, degree of thyroid dysfunction, comorbidity, serum thyrotropin, total thyroxine, and triiodothyronine, as well as thyroperoxidase and thyrotropin receptor antibody concentrations). The SF-36 Health Survey was used to analyze the effect of impaired sex life on overall QOL.

RESULTS

In the cross-sectional sample, 36% of women and 31% of men reported what they perceived to be thyroid-attributable impaired sex life. Women with autoimmune thyroid diseases reported more impairment than those with non-autoimmune thyroid diseases. In patients with Graves' disease lower levels of educational attainment and in patients with toxic nodular goiter comorbidities were associated with impaired sex life. Overall QOL was lower in patients with thyroid-related sex life impairment. In the longitudinal sample, 42% of women and 33% of men had impaired sex life at baseline, which improved at 6 months follow-up only in women and, when analyzing individual diagnoses separately, statistically significantly among those with autoimmune hypothyroidism. Sexual impairment was associated with low education in patients with toxic nodular goiter and with high plasma triiodothyronine concentrations in patients with Graves' disease. In autoimmune hypothyroidism, a younger age was associated with sex life impairment.

CONCLUSION

We found a high frequency of self-reported, thyroid-related sex life impairment in patients with benign thyroid diseases, especially in young women with autoimmune thyroid diseases. Self-perceived impaired sex life persisted in women treated for Graves' disease, suggesting that normalization of thyroid function was not sufficient to restore sexual function.

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.

No evidence of a causal relationship between hypothyroidism and glaucoma: A Danish nationwide register-based cohort study

Background

An interrelationship between hypothyroidism and glaucoma, due to a shared autoimmune background or based on deposition of mucopolysaccharides in the trabecular meshwork in the eye, has been suggested but is at present unsubstantiated. Therefore, our objective was to investigate, at a nationwide and population-based level, whether there is such an association.

Subjects and methods

Observational cohort study using record-linkage data from nationwide Danish health registers. 121,799 individuals diagnosed with a first episode of hypothyroidism were identified and were matched with 4 non-hypothyroid controls according to age and sex. Prevalence of glaucoma was recorded and cases and controls were followed over a mean of 7.1 years (range 0–17). Logistic and Cox regression models were used to assess the risk of glaucoma before and after the diagnosis of hypothyroidism, respectively.

Results

Overall, we found a higher prevalence of glaucoma in subjects with hypothyroidism as compared to controls (4.6% vs. 4.3%, p < 0.001). Prior to the diagnosis of hypothyroidism, the odds ratio (OR) was significantly increased for glaucoma [1.09; 95% confidence interval (CI): 1.04–1.13]. Based on the Cox regression model, there was no increased risk of glaucoma after the diagnosis of hypothyroidism [hazard ratio (HR) 1.00; 95% CI: 0.96–1.06], and the HR decreased further after adjusting for pre-existing co-morbidity (0.88; 95% CI: 0.84–0.93).

Conclusions

There was an increased risk of glaucoma before but not after the diagnosis of hypothyroidism, suggesting that screening for glaucoma in hypothyroid individuals is unwarranted.

The interrelation between hypothyroidism and glaucoma: a critical review and meta-analyses

Data on the association between hypothyroidism and glaucoma are conflicting. We sought to shed light on this by conducting a critical review and meta-analyses. The meta-analyses were conducted in adherence with the widely accepted MOOSE guidelines. Using the Medical Subject Heading (MeSH) terms: hypothyroidism, myxoedema and glaucoma or intraocular pressure, case-control studies, cohort studies and cross-sectional studies were identified (PubMed) and reviewed. Using meta-analysis, the relative risk (RR) of coexistence of glaucoma and hypothyroidism was calculated. Based on the literature search, thirteen studies fulfilled the inclusion criteria and could be categorized into two groups based on the exposure. The designs of the studies varied considerably, and there was heterogeneity related to lack of power, weak phenotype classifications and length of follow-up. Eight studies had glaucoma (5757 patients) as exposure and hypothyroidism as outcome. Among these, we found a non-significantly increased risk of hypothyroidism associated with glaucoma (RR 1.65; 95% confidence interval [CI]: 0.97-2.82). Based on five studies (168 006 patients) with hypothyroidism as exposure and glaucoma as outcome, we found the risk of glaucoma to be significantly increased (RR 1.33; 95% CI: 1.13-1.58). Based on these meta-analyses, there seems to be an association between hypothyroidism and glaucoma, which does not seem to be the case between glaucoma and hypothyroidism. However, larger scale studies with better phenotype classification, longer follow-up and taking comorbidity and other biases into consideration are needed to address a potential causal relationship.

Month of birth is associated with the subsequent diagnosis of autoimmune hypothyroidism. A nationwide Danish register-based study

BACKGROUND

The triggering of thyroid autoimmunity in the genetically susceptible remains a conundrum. Environmental exposures during gestation and/or early postnatally have proponents, as suggested in diabetes mellitus, with a higher incidence of births during spring and summer. Whether the development of autoimmune hypothyroidism (AIT) is influenced by month or season of birth is less clear.

METHOD

Nationwide cohort study of 111 565 individuals diagnosed with AIT and four euthyroid controls per case, matched according to age and sex, were identified from Danish health registers. Differences in month of birth across the year were evaluated by the Walter-Elwood test. The risk of patients with AIT being born in a certain month or season of the year was calculated using a Cox regression model.

RESULTS

There was a significant difference in birth month between cases and controls, P<.001. Individuals with AIT had a significantly increased risk of being born in June (Hazard ratio 1.04; 95% Confidence interval (CI): 1.02-1.08) and in the summer (June-August; HR 1.02; 95%CI: 1.01-1.04).

CONCLUSION

In this large-scale nationwide cohort study, we found a higher risk of AIT when born in the summer season or more specifically in June, supporting the hypothesis that seasonal variations in exposures-gestationally and/or early postnatally-may contribute to the development of AIT.

Insufficient documentation for clinical efficacy of selenium supplementation in chronic autoimmune thyroiditis, based on a systematic review and meta-analysis

By a systematic review and meta-analysis to investigate clinically relevant effects of selenium supplementation in patients with chronic autoimmune thyroiditis. Controlled trials in adults (≥18 years) with autoimmune thyroiditis, comparing selenium with or without levothyroxine substitution, versus placebo and/or levothyroxine substitution, were eligible for inclusion. Identified outcomes were serum thyrotropin (thyroid stimulating hormone) levels in LT4-untreated patients, thyroid ultrasound and health-related quality of life. Eleven publications, covering nine controlled trials, were included in the systematic review. Random effects model meta-analyses were performed in weighted mean difference for thyroid stimulating hormone, ultrasound and health-related quality of life. Quality of evidence was assessed per outcome, using GRADE. Meta-analyses showed no change in thyroid stimulating hormone, or improvements in health-related quality of life or thyroid echogenicity (ultrasound), between levothyroxine substitution-untreated patients assigned to selenium supplementation or placebo. Three trials found some improvement in wellbeing in patients receiving levothyroxine substitution, but could not be synthesized in a meta-analysis. The quality of evidence ranged from very low to low for thyroid stimulating hormone as well as ultrasound outcomes, and low to moderate for health-related quality of life, and was generally downgraded due to small sample sizes. We found no effect of selenium supplementation on thyroid stimulating hormone, health-related quality of life or thyroid ultrasound, in levothyroxine substitution-untreated individuals, and sporadic evaluation of clinically relevant outcomes in levothyroxine substitution-treated patients. Future well-powered RCTs, evaluating e.g. disease progression or health-related quality of life, are warranted before determining the relevance of selenium supplementation in autoimmune thyroiditis.

Nomogram for radiation-induced hypothyroidism prediction in nasopharyngeal carcinoma after treatment

OBJECTIVE

The aim of this study was to develop a nomogram for radiation-induced hypothyroidism (RHT) prediction.

METHODS

We collected data from 164 patients with nasopharyngeal carcinoma (NPC) in our previous prospective study. Biochemical hypothyroidism was defined as a serum thyroid-stimulating hormone level greater than the normal value. We collected both clinical and dose-volume factors. A univariate Cox regression analysis was performed to identify RHT risk factors. Optimal predictors were selected according to the least absolute shrinkage and selection operator (LASSO). We then selected the Cox regression models that best balanced the prediction performance and practicability to build a nomogram for RHT prediction.

RESULTS

There were 38 (23.2%) patients who developed RHT, and the median follow-up was 24 months. The univariate Cox regression analysis indicated that gender, minimum dose, mean dose (D_mean) and V₂₅-V₆₀ [V_x (%), the percentage of thyroid volume receiving >x Gy] of the thyroid were significantly associated with RHT. The variables of gender, receiving chemotherapy or not (chemo), D_mean and V₅₀ were selected using the LASSO analysis. A nomogram based on a three-variable (gender, chemo and V₅₀) Cox regression model was constructed, and its concordance index was 0.72. Good accordance between prediction and observation was showed by calibration curves in the probability of RHT at 18, 24 and 30 months.

CONCLUSION

This study built a nomogram for RHT in NPC survivors by analyzing both clinical and dose-volume parameters using LASSO. Thus, the individual dose constraint could be achieved in a visual format. Advances in knowledge: This study used LASSO to more accurately address the multicollinear problem between variables. The resulting nomogram will help physicians predict RHT.

Selenium Supplementation Significantly Reduces Thyroid Autoantibody Levels in Patients with Chronic Autoimmune Thyroiditis: A Systematic Review and Meta-Analysis

BACKGROUND

Selenium supplementation may decrease circulating thyroid autoantibodies in patients with chronic autoimmune thyroiditis (AIT), but the available trials are heterogenous. This study expands and critically reappraises the knowledge on this topic.

METHODS

A literature search identified 3366 records. Controlled trials in adults (≥18 years of age) with AIT, comparing selenium with or without levothyroxine (LT4), versus placebo and/or LT4, were eligible. Assessed outcomes were serum thyroid peroxidase (TPOAb) and thyroglobulin (TgAb) autoantibody levels, and immunomodulatory effects. After screening and full-text assessment, 16 controlled trials were included in the systematic review. Random-effects meta-analyses in weighted mean difference (WMD) were performed for 3, 6, and 12 months of supplementation in two different populations: one receiving LT4 therapy and one newly diagnosed and LT4-untreated. Heterogeneity was estimated using I², and quality of evidence was assessed per outcome, using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) guidelines.

RESULTS

In LT4-treated populations, the selenium group had significantly lower TPOAb levels after three months (seven studies: WMD = -271 [confidence interval (CI) -366 to -175]; p < 0.0001; I² = 45.4%), which was consistent at six months (three studies) and 12 months (one study). TgAb decreased at 12 months, but not at three or six months. In LT4-untreated populations, the selenium group showed a decrease in TPOAb levels after three months (three studies: WMD = -512 [CI -626 to -398]; p < 0.0001, I² = 0.0%), but not after 6 or 12 months. TgAb decreased at 3 months, but not at 6 or 12 months. Quality of evidence was generally assessed as low. Study participants receiving selenium had a significantly higher risk than controls of reporting adverse effects (p = 0.036).

CONCLUSIONS

Selenium supplementation reduced serum TPOAb levels after 3, 6, and 12 months in an LT4-treated AIT population, and after three months in an untreated AIT population. Whether these effects correlate with clinically relevant measures remains to be demonstrated.

Respiratory Manifestations of Hypothyroidism: A Systematic Review

BACKGROUND

Hypothyroidism has been associated with increased pulmonary morbidity and overall mortality. A systematic review was conducted to identify the prevalence and underlying mechanisms of respiratory problems among patients with thyroid insufficiency.

METHODS

PubMed and EMBASE databases were searched for relevant literature from January 1950 through January 2015 with the following study eligibility criteria: English-language publications; adult subclinical or overt hypothyroid patients; intervention, observational, or retrospective studies; and respiratory manifestations. The Preferred Reporting Items for Systematic reviews and Meta-Analyses statement was followed, and Cochrane's risk of bias tool was used.

RESULTS

A total of 1699 papers were screened by two independent authors for relevant titles. Of 109 relevant abstracts, 28 papers underwent full-text analyses, of which 22 were included in the review. Possible mechanisms explaining respiratory problems at multiple physiological levels were identified, such as the ventilator control system, diaphragmatic muscle function, pulmonary gas exchange, goiter caused upper airway obstruction, decreased capacity for energy transduction, and reduced glycolytic activity. Obstructive sleep apnea syndrome was found among 30% of newly diagnosed patients with overt hypothyroidism, and demonstrated reversibility following treatment. The evidence for or against a direct effect on pulmonary function was ambiguous. However, each of the above-mentioned areas was only dealt with in a limited number of studies. Therefore, it is not possible to draw any strong conclusions on any of these themes. Moreover, most studies were hampered by considerable risk of bias due for example to small numbers of patients, lack of control groups, randomization and blinding, and differences in body mass index, sex, and age between subjects and controls.

CONCLUSION

Mechanistic data linking hypothyroidism and respiratory function are at best limited. This area of research is therefore open for retesting hypotheses, using appropriate study designs and methods.