A review of the evidence for and against increased mortality in hypothyroidism

Capsiate ameliorates secondary hyperparathyroidism by improving insulin sensitivity and inhibiting angiogenesis

Secondary hyperparathyroidism has a significant impact on the overall well-being of the body. Capsiates, known for their antioxidant and metabolic properties, have emerged as a promising alternative treatment for secondary hyperparathyroidism. This study aims to evaluate the effects and mechanisms of capsiates in the treatment of secondary hyperparathyroidism. To achieve our research objectives, we conducted a study on patients' serum and examined changes in metabolic markers using serum metabolomics. We induced secondary hyperparathyroidism in rat through dietary intervention and divided them into four groups. The first group, referred to as the Parathyroid Hormone (PTH) group, received a low-calcium and high-phosphate diet (0.2% calcium, 1.2% phosphorus). The second group served as the control group, receiving a standard phosphate and calcium diet (0.6% calcium, 0.6% phosphorus). The third group, called the capsiates group, consisted of rat from the control group treated with capsiates (intraperitoneal injection of 2 mg/kg capsiates for 2 weeks after 2 weeks of dietary intervention). The fourth group was the capsiates-treated PTH group. Subsequently, we conducted ribose nucleic acid (RNA) sequencing on parathyroid gland cells and evaluated serum thyroxine levels, oxidative stress, expression of proteins associated with vascular neogenesis, measurement of SOD, GSH and 3-nitrotyrosine, micro-CT and histological staining. The serum metabolomic data revealed a significant decrease in capsiate levels in the secondary hyperparathyroidism group. Administration of capsiates to PTH rat resulted in increased calcium levels compared to the PTH group. Additionally, the PTH + Capsiates group showed significantly lower levels of PTH and phosphate compared to the PTH group. The PTH group exhibited a notable increase in the quantity and size of mitochondria compared to the control group. Following capsiates administration to the PTH group, there was a significant reduction in the number of mitochondria and length of microvilli, but an increase in the size of mitochondria compared to the PTH group. Sequencing analysis revealed that vascular endothelial growth factor (VEGF) and Vascular Endothelial Growth Factor Receptor 1 (VEGFR1) play crucial roles in this process. Vascular-related variables and downstream signalling were significantly elevated in hyperthyroidism and were alleviated with capsaicin treatment. Finally, combining capsiates with the PTH group improved bone mineral density, Tb.N, BV.TV, Cs.Th, Tt.Ar, OPG, Ob.TV and Oc.TV, as well as the mineral apposition rate, but significantly decreased Tb.Sp and Receptor Activator for Nuclear Factor-κ B Ligand (RANKL) compared to the PTH group. The findings suggest that capsiates can improve secondary hyperparathyroidism and ameliorated osteoporosis outcomes by inhibiting angiogenesis and reducing oxidative stress.

Investigating the shared genetic architecture between hypothyroidism and rheumatoid arthritis

Background

There is still controversy regarding the relationship between hypothyroidism and rheumatoid arthritis (RA), and there has been a dearth of studies on this association. The purpose of our study was to explore the shared genetic architecture between hypothyroidism and RA.

Methods

Using public genome-wide association studies summary statistics of hypothyroidism and RA, we explored shared genetics between hypothyroidism and RA using linkage disequilibrium score regression, ρ-HESS, Pleiotropic analysis under a composite null hypothesis (PLACO), colocalization analysis, Multi-Trait Analysis of GWAS (MTAG), and transcriptome-wide association study (TWAS), and investigated causal associations using Mendelian randomization (MR).

Results

We found a positive genetic association between hypothyroidism and RA, particularly in local genomic regions. Mendelian randomization analysis suggested a potential causal association of hypothyroidism with RA. Incorporating gene expression data, we observed that the genetic associations between hypothyroidism and RA were enriched in various tissues, including the spleen, lung, small intestine, adipose visceral, and blood. A comprehensive approach integrating PLACO, Bayesian colocalization analysis, MTAG, and TWAS, we successfully identified TYK2, IL2RA, and IRF5 as shared risk genes for both hypothyroidism and RA.

Conclusions

Our investigation unveiled a shared genetic architecture between these two diseases, providing novel insights into the underlying biological mechanisms and establishing a foundation for more effective interventions.

The role of primary cilia in thyroid diseases

Primary cilia (PC) are non-motile and microtube-based organelles protruding from the surface of almost all thyroid follicle cells. They maintain homeostasis in thyrocytes and loss of PC can result in diverse thyroid diseases. The dysfunction of structure and function of PC are found in many patients with common thyroid diseases. The alterations are associated with the cause, development, and recovery of the diseases and are regulated by PC-mediated signals. Restoring normal PC structure and function in thyrocytes is a promising therapeutic strategy to treat thyroid diseases. This review explores the function of PC in normal thyroid glands. It summarizes the pathology caused by PC alterations in thyroid cancer (TC), autoimmune thyroid diseases (AITD), hypothyroidism, and thyroid nodules (TN) to provide comprehensive references for further study.

Iodine-induced thyroid dysfunction: a scientometric study and visualization analysis

Objective

Iodine is essential in thyroid hormone production. Iodine deficiency is associated with serious complications (i.e miscarriage and stillbirth), whereas excess can cause thyroid dysfunction (i.e hyperthyroidism, hypothyroidism, thyroid autoimmunity). We conducted this scientometric study to visualize hot spots and trends in iodine-induced thyroid dysfunction over past two decades. The aim of this paper was to help scholars quickly understand the development and potential trend in this field, and guide future research directions.

Methods

Articles on iodine-induced thyroid dysfunction from 2000 to 2022 were retrieved from the Web of Science Core Collection (WoSCC) using the following search terms: (((((TS=(hypothyroid*)) OR TS=(hyperthyroid*)) OR TS= ("TSH deficiency")) OR TS= ("thyroid stimulating hormone deficiency")) AND TS=(Iodine)) NOT TS=(radioiodine). Only publications in English were selected. CiteSpace, VOSviewer, Tableau, Carrot2, and R software were used to analyze the contribution and co-occurrence relationships of different countries, institutes, keywords, references, and journals.

Results

A total of 2986 publications from 115 countries and 3412 research institutions were included. From 2000 to 2022, research on iodine-induced thyroid dysfunction progressed over a three-stage development period: initial development (2000-2009), stable development (2010-2016), and rapid development (2016-2022) period. The Journal of Clinical Endocrinology and Metabolism had the most co-citations followed and China Medical University (n=76) had the most publications. The top three clusters of co-citation references were isolated maternal hypothyroxinemia, subclinical hyperthyroidism, and brain development. Various scientific methods were applied to reveal acknowledge structure, development trend and research hotspots in iodine-induced thyroid dysfunction.

Conclusion

Our scientometric analysis shows that investigations related to pregnant women, epidemiology surveys, and iodine deficiency are promising topics for future iodine-induced thyroid dysfunction research and highlights the important role of iodine on thyroid function.

A study of cardiovascular profile in patients with primary hypothyroidism

Introduction and Aim: Raised cardiovascular morbidity is common among patients with primary hypothyroidism. Study of electrocardiogram (ECG) and echocardiography (ECHO) and correlation with lipid profile may help in early detection of cardiovascular diseases in hypothyroidism. By this study, we aimed at studying the cardiovascular profile in patients with primary hypothyroidism and correlating ECHO and ECG changes in primary hypothyroidism with the LDL cholesterol.  Materials and Methods: This was a single centre cross-sectional observational study. All patients diagnosed with primary hypothyroidism were included. The laboratory parameters pertaining to primary hypothyroidism were recorded. ECG and ECHO were noted and correlated with lipid profile.   Results: Total 240 subjects were selected according to inclusion and exclusion criteria, of which males were 25% and females 75%. Mean ± SD of LDL-C among subjects having ST-T changes was 160.98 ±14.86. Mean ± SD of LDL-C among subjects having no ST-T changes was 128±10.15. Unpaired student t test was used to compare mean of lipid profile in patient having ST-T changes with patients having no ST-T changes. A strong correlation was observed between LDL cholesterol and ST-T changes in ECG (P value =0.001) Conclusion: Diastolic dysfunction is more common than systolic dysfunction in primary hypothyroidism. LDL levels were high in patients with primary hypothyroidism who had ST-T changes in electrocardiogram. Levothyroxine replacement causes decrease in Total as well as LDL cholesterol in primary hypothyroidism. ECG changes correlated with abnormal lipid profile in patients with primary hypothyroidism.  

Prognostic role of hypothyroidism and low free-triiodothyronine levels in patients hospitalized with acute heart failure

Low thyroid function has been widely recognized as a potential cause of heart failure (HF), but the evidence about a possible association with in-hospital, all-cause mortality in patients with acute HF (AHF) is not consistent. This study sought to investigate the prevalence and prognostic role of hypothyroidism, overt and subclinical, and of low free-triiodothyronine (fT3) levels in patients hospitalized with AHF. We retrospectively analyzed consecutive 1018 patients who were hospitalized for AHF in a single academic medical center [Fondazione Policlinico A.Gemelli IRCCS, Rome, Italy] between January 1st 2016, and December 31st 2018. Patients were divided into three groups: normal thyroid function (n = 798), subclinical hypothyroidism (n = 105), and overt hypothyroidism (n = 115). The outcome was in-hospital, all-cause mortality. Patients were 81 years of age, 55% were females and nearly two-thirds of the patients were on New York Heart Association functional class III. The three most common cardiovascular comorbidities were coronary artery disease, hypertension, and atrial fibrillation with no differences across the three groups. Overall, 138 patients (14%) died during the hospital stay. The mortality rate was 27% among patients with overt hypothyroid, 17% among those with subclinical hypothyroidism, and 11% among euthyroid patients (p < 0.001). At a multivariate Cox regression model, overt hypothyroidism (HR 2.1, 95% CI 1.4-3.2) and fT3 levels < 1.8 pg/mL (HR 3.4, 95% CI 2.3-5.1) were associated with an increased likelihood of in-hospital death. No association was found with subclinical hypothyroidism. Among patients hospitalized with AHF, overt hypothyroidism and low fT3 levels are independent predictors of all-cause mortality during the hospital stay.

Radiation-induced hypothyroidism in patients with nasopharyngeal carcinoma treated with intensity-modulated radiation therapy with or without chemotherapy: Development of a nomogram based on the equivalent dose

OBJECTIVE

The aim of this study was to establish a nomogram for predicting radiation-induced hypothyroidism (RHT) based on an equivalent dose at 2 Gy per fraction (EQD₂) in patients with nasopharyngeal carcinoma (NPC) treated with intensity-modulated radiation therapy (IMRT) with or without chemotherapy.

METHODS

Two hundred forty-four eligible patients with NPC were recruited for this study. Patients' clinical factors and dose-volume parameters of the thyroid gland were retrieved from medical records and the IMRT treatment planning system, respectively. The irradiation doses were converted into EQD₂ for analysis. Least absolute shrinkage and selection operator (LASSO) regression analysis and multivariate logistic regression analysis were performed to identify optimal predictors of RHT for constructing the nomogram.

RESULTS

With a median follow-up of 63.0 months, the cumulative incidence rates of RHT at 3 months and 1-, 2-, 3-, 4- and 5- year after IMRT were 10.2%, 36.2%, 47.6%, 54.2%, 58.8% and 69.4%, respectively. Four independent factors for predicting RHT, including gender, age, pretreatment volume of the thyroid gland and V_35Gy(3Gy) of the thyroid gland, were identified and incorporated into the nomogram. The area under the ROC curve of the nomogram was 0.747 (95% confidence interval 0.685 - 0.809). Calibration curves and DCA curves showed that the nomogram was in good agreement with the actual observations and clinical usefulness.

CONCLUSIONS

The nomogram proposed in this study provides a reliable estimate of RHT risk in patients with NPC after IMRT and appears to have the potential to be a useful tool for widespread clinical applications.

Thyroid hormones in diabetes, cancer, and aging

Thyroid function is central in the control of physiological and pathophysiological processes. Studies in animal models and human research have determined that thyroid hormones modulate cellular processes relevant for aging and for the majority of age‐related diseases. While several studies have associated mild reductions on thyroid hormone function with exceptional longevity in animals and humans, alterations in thyroid hormones are serious medical conditions associated with unhealthy aging and premature death. Moreover, both hyperthyroidism and hypothyroidism have been associated with the development of certain types of diabetes and cancers, indicating a great complexity of the molecular mechanisms controlled by thyroid hormones. In this review, we describe the latest findings in thyroid hormone research in the field of aging, diabetes, and cancer, with a special focus on hepatocellular carcinomas. While aging studies indicate that the direct modulation of thyroid hormones is not a viable strategy to promote healthy aging or longevity and the development of thyromimetics is challenging due to inefficacy and potential toxicity, we argue that interventions based on the use of modulators of thyroid hormone function might provide therapeutic benefit in certain types of diabetes and cancers.

Analysis of factors related to preterm birth: a retrospective study at Nanjing Maternity and Child Health Care Hospital in China

Preterm birth is the most important cause of neonatal mortality and morbidity worldwide. The aim of this study was to identify factors associated with preterm birth and examine the heterogeneity and interactions between these factors.We collected data from 1607 pregnant women treated at Nanjing Maternity and Child Health Care Hospital in China. The women included in the study were divided into the full-term group and the preterm-birth group. We used t-tests to compare the characteristics of age and body mass index, Chi-square tests for the other variables, and we used the Wald test to calculate the interaction between factors that may affect preterm birth. The heterogeneity test was used to study the relationship between subgroups. Multivariable logistic regression analysis was used to explore the associations between risk factors and preterm birth, which included all risk factors. All tests were 2-tailed, P < 0.05 was considered significant, and 95% confidence intervals were estimated for percentages.There was no statistical difference in basic characteristics such as age between the full-term and preterm groups. We found 6 independent risk factors that were associated with preterm birth (P < .05): preeclampsia (PE), intrahepatic cholestasis, premature rupture of the membranes (PROM), placenta previa, chorioamnionitis, and scarred uterus. Five combinations of these factors were statistically significant (P < .05) in terms of heterogeneity: PE and PROM; placenta previa and polyhydramnios; chorioamnionitis and PE; PROM and maternal body mass index; and PROM and gestational diabetes mellitus. Ultimately, the 2 subgroups that showed interactions were PE and PROM and chorioamnionitis and PE.The interaction between different factors over the course of preterm birth cannot be ignored. When independent risk factors are combined with other diseases, such as PE combined with PROM or chorioamnionitis in this study, it may more likely result in preterm birth. Thus, this situation deserves particular clinical attention.

Association of Hypothyroidism and Mortality in the Elderly Population: A Systematic Review and Meta-Analysis

CONTEXT

The evidence of whether hypothyroidism increases mortality in the elderly population is currently inconsistent and conflicting.

OBJECTIVE

The objective of this meta-analysis is to determine the impact of hypothyroidism on mortality in the elderly population.

DATA SOURCES

PubMed, Embase, Cochrane Library, Scopus, and Web of Science databases were searched from inception until May 10, 2019.

STUDY SELECTION

Studies evaluating the association between hypothyroidism and all-cause and/or cardiovascular mortality in the elderly population (ages ≥ 60 years) were eligible.

DATA EXTRACTION

Two reviewers independently extracted data and assessed the quality of the studies. Relative risk (RR) was retrieved for synthesis. A random-effects model for meta-analyses was used.

DATA SYNTHESIS

A total of 27 cohort studies with 1 114 638 participants met the inclusion criteria. Overall, patients with hypothyroidism experienced a higher risk of all-cause mortality than those with euthyroidism (pooled RR = 1.26, 95% CI: 1.15-1.37); meanwhile, no significant difference in cardiovascular mortality was found between patients with hypothyroidism and those with euthyroidism (pooled RR = 1.10, 95% CI: 0.84-1.43). Subgroup analyses revealed that overt hypothyroidism (pooled RR = 1.10, 95% CI: 1.01-1.20) rather than subclinical hypothyroidism (pooled RR = 1.14, 95% CI: 0.92-1.41) was associated with increased all-cause mortality. The heterogeneity primarily originated from different study designs (prospective and retrospective) and geographic locations (Europe, North America, Asia, and Oceania).

CONCLUSIONS

Based on the current evidence, hypothyroidism is significantly associated with increased all-cause mortality instead of cardiovascular mortality among the elderly. We observed considerable heterogeneity, so caution is needed when interpreting the results. Further prospective, large-scale, high-quality studies are warranted to confirm these findings.

Growing up different in Neolithic China: A contextualised case study and differential diagnosis of a young adult with skeletal dysplasia

This paper presents a case study of a young adult from the late Neolithic Yangshao cultural period site (∼3300-2900 years BC) of Guanjia () located in Henan Province on the Central Plains of China, who has evidence for skeletal dysplasia characterised by proportional stunting of the long bones and a small axial skeleton, generalised osteopenia, and non-fusion of epiphyses. We provide a detailed differential diagnosis of skeletal dysplasia with paediatric onset and conclude that this is likely a form of hypopituitarism or hypothyroidism, an extremely rare finding within the archaeological context. This paper highlights the issues of distinguishing the forms of proportional dwarfism in palaeopathology because of the considerable variation in manifestation of these conditions. Finally, we assess whether there were any health and social implications for this person and community through the consideration of a bioarchaeology of care approach across the lifecourse, burial context, and information on social perceptions of 'difference' in the community. ：： （3300～2900）。，，，，。，，。。，。，、、""，。.

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.

Longitudinal Change in Thyroid Hormone Levels in Children with Epilepsy on a Ketogenic Diet: Prevalence and Risk Factors

Background and Purpose

The aim of this study is to evaluate the prevalence of hypothyroidism and the change of thyroid hormone level in the children with epilepsy on a ketogenic diet (KD).

Methods

The levels of serum free thyroxine (fT4) and thyroid-stimulation hormone (TSH) were measured at the start of the KD and at 6- to 12-month intervals in children with intractable epilepsy. Hypothyroidism was defined as fT4 level < 0.8 ng/dL and TSH level > 6.0 μIU/mL.

Results

A total of 28 children (17 boys and 11 girls) were enrolled in the study. The mean age of onset of seizure was 1.4 ± 1.6 years, the mean age of the start of the KD was 3.2 ± 2.4 years, and the mean duration of KD was 1.9 ± 1.5 years. Overall, there was no significant longitudinal change in the mean fT4 (0.99 ± 0.25 vs. 0.94 ± 0.71 ng/dL, p = 0.28) and TSH (2.94 ± 1.32 vs. 3.18 ± 1.21 μIU/mL, p = 0.44) levels from the start of the KD to last follow-up. The patients with a younger age of seizure onset, earlier initiation of KD, and higher serum levels of cholesterol and triglyceride had a significant decrease in fT4 levels and increase in TSH levels during the KD. Sex, duration of the seizure or KD therapy, seizure types, seizure frequency, seizure outcomes, brain lesion, ratio of KD, and being overweight did not affect the longitudinal change of fT4 and TSH levels during KD.

Conclusion

Thyroid function had no significant longitudinal decrease in pediatric epilepsy during KD therapy. However, careful monitoring of the serum levels of fT4/TSH should be recommended in children on KDs, especially in those with earlier seizure onset, earlier start of KD, and higher levels of lipid profiles.

Mortality in persons with undetected and diagnosed hypertension, type 2 diabetes, and hypothyroidism, compared with persons without corresponding disease - a prospective cohort study; The HUNT Study, Norway

Background

Suggested strategies in reducing the impact of non-communicable diseases (NCD) are early diagnosing and screening. We have limited proof of benefit of population screening for NCD. Increased mortality in persons with diagnosed NCD has been shown for decades. However, mortality in undetected NCD has barely been studied. This paper explores whether all-cause mortality differed between persons with diagnosed hypothyroidism, type 2 diabetes (T2DM), and hypertension, compared with persons with undetected-, and with persons without the corresponding disease.

Methods

A prospective cohort study of the general population in Nord-Trøndelag, Norway. Persons ≥20 years at baseline 1995–97 were followed until death or June 15, 2016. Cox proportional hazards models were used to compute age and multiple adjusted hazard ratios (HR) with 95% confidence intervals (CI) for the association between disease status and all-cause mortality. The number of participants in the hypothyroidism study was 31,960, in the T2DM study 37,957, and in the hypertension study 63,371.

Results

Mortality was increased in persons with diagnosed type 2 diabetes and hypertension, compared to persons without corresponding disease; HR 1.69 (95% CI 1.55–1.84) and HR 1.23 (95% CI 1.09–1.39), respectively. Among persons with undetected T2DM, the HR was 1.21 (95% CI 1.08–1.37), whilst among undetected hypothyroidism and hypertension, mortality was not increased compared with persons without the diseases. Further, the association with mortality was stronger in persons with long duration of T2DM (HR 1.96 (95% CI 1.57–2.44)) and hypertension (HR 1.32 (95% CI 1.17–1.49)), compared with persons with short duration (HR 1.29 (1.09–1.53) and HR 1.16 (1.03-1-30) respectively).

Conclusions

Mortality was increased in persons with diagnosed T2DM and hypertension, and in undetected T2DM, compared with persons without the diseases. The strength of the association with mortality in undetected T2DM was however lower compared with persons with diagnosed T2DM, and mortality was not increased in persons with undetected hypothyroidism and hypertension, compared with persons without the diseases. Thus, future research needs to test more thoroughly if early diagnosing of these diseases, such as general population screening, is beneficial for health.

Pre-admission TSH levels predict long-term mortality in adults treated for hypothyroidism

CONTEXT

Limited data is available regarding the association between pre-admission thyroid function and prognosis of hospitalized patients treated for hypothyroidism.

OBJECTIVE

Evaluate an association between thyroid stimulating hormone (TSH) levels and mortality in hospitalized levothyroxine-treated patients.

DESIGN AND SETTING

Observational data of patients admitted to medical wards between 2011 and 2013. TSH levels obtained up to 180 days prior to admission were stratified as follows: low (≤0.5 mIU/L), normal (0.5-5 mIU/L), high (>5 mIU/L).

PATIENTS

Patients aged 60-80 years with available thyroid function tests were matched with controls without hypothyroidism.

MAIN OUTCOME

All-cause mortality up to 66-months following discharge.

RESULTS

One thousand and fifty seven patients (73% females, mean (SD) age 71 ± 6 years) were matched with controls without hypothyroidism. Mean hospital stay and in-hospital mortality were not different between groups. Mortality risk at the end-of-follow-up was 41% (438/1057) and 37% (392/1057) for patients with and without hypothyroidism (p < 0.05). TSH levels were classified as follows: low, 84 patients (8%); normal, 667 patients (63%); high, 306 patients (29%). Length of hospitalization and in-hospital mortality were not different between TSH categories. Mortality risk at the end-of-follow-up was 30, 39, and 50% with low, normal and elevated TSH, respectively. Adjusted hazard ratio (95% CI) of mortality at the end-of-follow-up was of 2.2 (1.2-3.8) for high vs. low TSH levels, and 1.4 (1.1-1.9) for high vs. normal TSH levels.

CONCLUSION

In treated hypothyroid adult patients, increased TSH up to 6 months prior to admission is associated with increased mortality. Treatment should aim at achieving euthyroidism to improve survival.

Hormonal contraception and the development of autoimmunity: A review of the literature

Estrogens and progestins are known to have profound effects on the immune system and may modulate the susceptibility to autoimmune diseases. A comprehensive literature search was carried out using PubMed for any of 153 autoimmune disease terms and the terms contraception, contraceptive, or their chemical components with limits of Humans + Title or Abstract. Over 1,800 titles were returned and scanned, 352 papers retrieved and reviewed in depth and an additional 70 papers retrieved from the bibliographies. Based on this review, substantial evidence exists linking the use of combined oral contraceptives to a lower incidence of hyperthyroidism, an increase in multiple sclerosis, ulcerative colitis, Crohn's disease, Systemic Lupus Erythematosus, and interstitial cystitis. Progesterone only contraceptives are linked to progesterone dermatitis and in one large developing world concurrent cohort study are associated with increases in arthropathies and related disorders, eczema and contact dermatitis, pruritis and related conditions, alopecia, acne, and urticaria. Hormonal contraceptives modulate the immune system and may influence the susceptibility to autoimmune diseases with significant increases in risk for several autoimmune diseases.

SUMMARY

Hormonal contraceptives (HCs), such as the "pill," Norplant, and vaginal rings, are very potent hormones that have effects on the immune system, which is made up of white blood cells and lymph nodes and normally defends the body against invading bacteria, viruses and parasites. This review looked at the association of HC use to the development of autoimmune diseases, where the immune system turns against the body and causes damage to organs. There is good evidence that HC use is associated with an increased risk of several serious autoimmune diseases such as Crohn's disease (which causes inflammation of the bowels), Lupus (which causes inflammation in many organs), and interstitial cystitis (which causes inflammation in the bladder). Several other rarer autoimmune diseases are also linked to HC use. People contemplating the use of HCs should be informed of these risks.

Hyperthyroidism, Hypothyroidism, and Cause-Specific Mortality in a Large Cohort of Women

BACKGROUND

The prevalence of hyperthyroidism and hypothyroidism is 0.5-4% in iodine-replete communities, but it is 5-10 times higher in women than in men. Those conditions are associated with a broad range of metabolic disorders and cardiovascular diseases. Biological evidence of a role of thyroid hormones in carcinogenesis also exists. However, the association between thyroid dysfunction and cardiovascular disease or cancer mortality risk remains controversial. In a large cohort of women, the associations of hyperthyroidism and hypothyroidism with cause-specific mortality were evaluated after nearly 30 years of follow-up.

METHODS

The prospective study included 75,076 women aged 20-89 years who were certified as radiologic technologists in the United States in 1926-1982, completed baseline questionnaires in 1983-1998 from which medical history was ascertained, and reported no malignant disease or benign thyroid disease except thyroid dysfunction. A passive follow-up of this cohort was performed through the Social Security Administration database and the National Death Index-Plus. Cause-specific mortality risks were compared according to self-reported thyroid status, with proportional hazards models adjusted for baseline year and age, race/ethnicity, body mass index, family history of breast cancer, and life-style and reproductive factors.

RESULTS

During a median follow-up of 28 years, 2609 cancer, 1789 cardiovascular or cerebrovascular, and 2442 other non-cancer deaths were recorded. Women with hyperthyroidism had an elevated risk of breast cancer mortality after 60 years of age (hazard ratio [HR] = 2.04 [confidence interval (CI) 1.16-3.60], 13 cases in hyperthyroid women) compared to women without thyroid disease. Hypothyroid women had increased mortality risks for diabetes mellitus (HR = 1.58 [CI 1.03-2.41], 27 cases in hypothyroid women), cardiovascular disease (HR = 1.20 [CI 1.01-1.42], 179 cases), and cerebrovascular disease (HR = 1.45 [CI 1.01-2.08], 35 cases, when restricting the follow-up to ≥10 years after baseline). Other causes of death were not associated with hyperthyroidism or hypothyroidism, though there was a suggestion of an elevated risk of ovarian cancer mortality in hyperthyroid women based on very few cases.

CONCLUSION

The excess mortality risks observed in a large, prospective 30-year follow-up of patients with thyroid dysfunction require confirmation, and, if replicated, further investigation will be needed because of the clinical implications.

Intensity modulated radiotherapy with fixed collimator jaws for locoregional left-sided breast cancer irradiation

The purpose of this study is to evaluate the intensity modulated radiotherapy (IMRT) with the fixed collimator jaws technique (FJT) for the left breast and regional lymph node. The targeted breast tissue and the lymph nodes, and the normal tissues were contoured for 16 left-sided breast cancer patients previously treated with radiotherapy after lumpectomy. For each patient, treatment plans using different planning techniques, i.e., volumetric modulated arc therapy (VMAT), tangential IMRT (tangential-IMRT), and IMRT with FJT (FJT-IMRT) were developed for dosimetric comparisons. A dose of 50Gy was prescribed to the planning target volume. The dose-volume histograms were generated, and the paired t-test was used to analyze the dose differences. FJT-IMRT had similar mean heart volume receiving 30Gy (V30 Gy) with tangential-IMRT (1.5% and 1.6%, p = 0.41), but inferior to the VMAT (0.8%, p < 0.001). In the average heart mean dose comparison, FJT-IMRT had the lowest value, and it was 0.6Gy lower than that for the VMAT plans (p < 0.01). A significant dose increase in the contralateral breast and lung was observed in VMAT plans. Compared with tangential-IMRT and VMAT plans, FJT-IMRT reduced the mean dose of thyroid, humeral head and cervical esophageal by 47.6% (p < 0.01) and 45.7% (p < 0.01), 74.3% (p = < 0.01) and 73% (p = < 0.01), and 26.7% (p = < 0.01) and 29.2% (p = < 0.01). In conclusion, compared with tangential-IMRT and VMAT, FJT-IMRT plan has the lowest thyroid, humeral head and cervical esophageal mean dose and it can be a reasonable treatment option for a certain subgroup of patients, such as young left-breast cancer patients and/or patients with previous thyroid disease.

Adding carbimazole to levothyroxine increases triiodothyronine and improves outcome in patients with primary hypothyroidism: a preliminary study from Egypt

BACKGROUND

Many hypothyroid patients are not tolerant and not satisfied with levothyroxine (LT4). Older studies used large doses of both carbimazole and LT4 for Hashimoto's thyroiditis (HT), because Graves' disease (GD) and HT were considered as very closely related syndromes produced by thyroid autoimmunity.

OBJECTIVE

The aim of the study was to determine the outcome after adding small doses of carbimazole to reduced doses of LT4 for patients with primary hypothyroidism, who are unable to tolerate LT4.

METHODS

The study is a non-randomized, single arm, interventional study. It included 19 female patients diagnosed with primary hypothyroidism who could not tolerate LT4. Subjects were recruited from the outpatient clinic of AL-Azhar University Hospital in Damietta, Egypt from January to March 2015. They were divided into two groups; group 1 included 10 patients with HT and 2 patients with non-specified primary hypothyroidism, and group 2 included 7 patients with subtotal thyroidectomy for GD. All patients received carbimazole (10 mg/day) beside LT4 (25 μg thrice/week) for 10 weeks. Statistical analysis of the data was done by SPSS version 20, using paired-sample t-test, ANOVA, Chi square, and Pearson coefficient test.

RESULTS

There was significant increase in free triiodothyronine (FT3) in addition to significant improvement in depression and LT4 tolerance in the whole population. There was non-significant improvement in TSH in group 1 (p=0.053). Surprisingly, in group 2, in spite of significant increase in TSH (p=0.007) and non-significant decrease in free thyroxine (FT4), there was non-significant increase in FT3. Whether carbimazole improves the pathology of the hypothyroid gland or the peripheral deiodination of T4 to T3 (where the serum and tissue levels of the latter may be responsible for improvement of symptoms) is in need of investigation.

CONCLUSIONS

Adding carbimazole to LT4 improves FT3, LT4 tolerance, and depression in primary hypothyroid female patients. Further studies are required to determine the appropriate doses of this regimen in different cases.

CLINICAL TRIAL REGISTRATION

This study was registered at Thai Clinical Trials Registration center (http://www.clinicaltrials.in.th) with registration ID: TCTR20170123003.

FUNDING

The study received no fund or grant.

Elevated TSH in adults treated for hypothyroidism is associated with increased mortality

CONTEXT

Numerous studies investigated the link between hypothyroidism and mortality, but a definite conclusion is hard to reach as these were limited by a number of factors, including age of participants, comorbidities and single measurement of thyroid function.

OBJECTIVE

To evaluate the association between TSH and fT4 levels and mortality in patients with levothyroxine-treated hypothyroidism.

DESIGN AND SETTING

Observational data of hospitalized patients (2011-2014). TSH and fT4 levels obtained between at least 30 days after discharge and until death or end of follow-up were collected. Median TSH and fT4 levels were stratified into categories.

PATIENTS

In total, 611 patients with treated hypothyroidism, aged 60-80 years (72% females, mean age 71 ± 6 years) were included in the study.

MAIN OUTCOME MEASURE

All-cause mortality up to 66 months after discharge, by TSH and fT4 categories.

RESULTS

During follow-up, the average numbers of TSH and fT4 measurements were 5.5 ± 3.8 and 2.5 ± 4.2 per patient respectively. Mortality rates were 28%, 29% and 54% with median TSH of 0.5-2.5, 2.5-5.0 and 5.0-10.0 IU/L respectively. Adjusted hazard ratios for mortality with median TSH between 5.0 and 10.0 IU/L were 2.3 (95% CI: 1.6-3.4) and 2.2 (95% CI: 1.6-3.2) compared with patients with TSH between 0.5-2.5 IU/L and 2.5-5 IU/L respectively. There was no difference in mortality between patients with median fT4 10-15 or 15-20 pmol/L.

CONCLUSION

In treated hypothyroid adult patients and serial measurements of thyroid function tests, median TSH levels of 5-10 IU/L are associated with increased mortality with no effect of fT4 levels. Treatment should aim at achieving euthyroidism to improve survival.

FREE THYROID HORMONES AND MORTALITY IN CAUCASIANS UNDERGOING ANGIOGRAPHY: THE LUDWIGSHAFEN RISK AND CARDIOVASCULAR HEALTH (LURIC) STUDY

OBJECTIVE

Alterations in thyroid hormone functions are associated with mortality and morbidity. Data on euthyroid individuals are very limited and controversial. We therefore investigated the relationship between circulating thyroid hormones and all-cause and cardiovascular (CV) mortality in participants of the Ludwigshafen Risk and Cardiovascular Health (LURIC) study and their association with morbidity.

METHODS

LURIC, a prospective, observational study of a hospital-based cohort of Caucasians, was recruited between June 1997 and May 2001 at the Ludwigshafen General Hospital, Ludwigshafen, Germany. Mortality was recorded for a follow-up period of 10 years. The current investigation includes 2,507 patients without overt thyroid disease who all underwent coronary angiography. Blood was drawn before angiography. We evaluated the association between thyroid hormone concentrations and mortality.

RESULTS

Low free triiodothyronine (FT3) (hazard ratio [HR], 1.00 versus 0.54; lowest versus highest quartile) and high free thyroxine (FT4) (HR, 1.52 versus 1.00; highest versus lowest quartile) were significant predictors of all-cause and CV mortality, independent of age and sex. Thyroid-stimulating hormone showed no consistent correlation with mortality.

CONCLUSION

High FT4 and low FT3 concentrations are significantly related to all-cause and CV mortality. These findings suggest that free thyroid hormones should be measured and considered in patients at intermediate to high risk of coronary heart disease.

ABBREVIATIONS

BMI = body mass index CAD = coronary artery disease CCI = Charlson Comorbidity Index CI = confidence interval CV = cardiovascular eGFR = estimated glomerular filtration rate FT3 = free triiodothyronine FT4 = free thyroxine HR = hazard ratio T3 = triiodothyronine T4 = thyroxine TSH = thyroid-stimulating hormone.

The interaction between thyroid and kidney disease: an overview of the evidence

PURPOSE OF REVIEW

Hypothyroidism is highly prevalent in chronic kidney disease (CKD) patients, including those receiving dialysis. This review examines potential mechanistic links between thyroid and kidney disease; current evidence for hypothyroidism as a risk factor for de novo CKD and CKD progression; and studies of thyroid functional disorders, cardiovascular disease, and death in the CKD population.

RECENT FINDINGS

Epidemiologic data have demonstrated an incrementally higher prevalence of hypothyroidism with increasing severity of kidney dysfunction. Various thyroid functional test abnormalities are also commonly observed in CKD due to alterations in thyroid hormone synthesis, metabolism, and regulation. Although the mechanistic link between thyroid and kidney disease remains unclear, observational studies suggest that hypothyroidism is associated with abnormal kidney structure and function. Previously thought to be a physiologic adaptation, recent studies show that hypothyroidism is associated with higher risk of cardiovascular disease and death in CKD.

SUMMARY

A growing body of evidence suggests that hypothyroidism is a risk factor for incident CKD, CKD progression, and higher death risk in kidney disease patients. Rigorous studies are needed to determine the impact of thyroid hormone replacement upon kidney disease progression, cardiovascular disease, and mortality, which may shed light onto the causal implications of hypothyroidism in CKD.

Thyroid Function Test Derangements and Mortality in Dialysis Patients: A Systematic Review and Meta-analysis

BACKGROUND

We evaluated current evidence associating thyroid function test result derangements with risk for mortality in patients with chronic kidney failure treated by long-term dialysis.

STUDY DESIGN

Systematic review and meta-analysis of cohort studies.

SETTING & POPULATION

Dialysis patients.

SELECTION CRITERIA FOR STUDIES

We searched PubMed, Web of Science, Science Citation Index, Cochrane Library, and Embase databases from inception through December 2015.

PREDICTORS

Hypothyroidism (thyrotropin level greater than reference range) and low triiodothyronine (T₃) and thyroxine (T₄) levels.

OUTCOMES

All-cause and cardiovascular mortality.

RESULTS

12 studies involving 14,766 participants (4,450 deaths) were identified. Of those, 6 studies provided data for cardiovascular mortality (2,772 participants with 327 cardiovascular deaths). Overall, confidence in the available evidence was moderate. Pooled adjusted HRs for all-cause mortality associated with hypothyroidism, low T₃ level, and low T₄ level were 1.24 (95% CI, 1.14-1.34), 1.67 (95% CI, 1.23-2.27), and 2.40 (95% CI, 1.47-3.93), respectively. Pooled adjusted HRs for cardiovascular mortality associated with low T₃ and T₄ levels were 1.84 (95% CI, 1.24-2.74) and 3.06 (95% CI, 1.29-7.24), respectively.

LIMITATIONS

Fewer studies reporting on T₄ and thyrotropin outcomes.

CONCLUSIONS

In patients treated with long-term dialysis, (cardiovascular) mortality is consistently higher in the presence of thyroid function test result derangements.

Levothyroxine but Not Selenium Increases Endothelial Progenitor Cell Counts in Patients with Hypothyroidism

BACKGROUND

Hypothyroidism is a common endocrine disease associated with increased oxidative stress, increased cardiovascular (CV) risk, CV events and endothelial dysfunction. Endothelial progenitor cells (EPCs) are a well-known marker of CV risk.

OBJECTIVE

The aim of this work was to ascertain whether hypothyroidism is associated with lower EPC counts and if treatment with levothyroxine (LT4) or selenium (Se) improves EPC counts compared to placebo.

METHODS

Hypothyrod patients (n = 100) were randomly divided into five groups to receive placebo (group A), LT4 (group B) or Se at doses of 83 µg (group C), 166 µg (group D) or 249 µg (group E) for 3 months. Each group comprised 20 patients: 10 with 'mild' hypothyroidism and 10 with 'severe' hypothyroidism. A healthy control group (group F) with 20 euthyroid subjects was also recruited. Subjects had to be free of CV disease, diabetes and drugs that interfere with EPCs. Anthropometric measurements (height, weight, BMI), blood pressure, fasting lipids and EPC analyses were performed at baseline and after 3 months.

RESULTS

EPC counts were significantly lower in hypothyroid patients compared to controls. EPCs increased after 3 months of treatment with LT4, but not with Se at any dosage. CD133+ and CD34+ EPC counts were negatively correlated with thyroid-stimulating hormone (TSH; r (2) = 0.523, p < 0.01 and r (2) = 0.517, p < 0.01, respectively) and positively correlated with FT4 (r (2) = 0.394, p < 0.01 and r (2) = 0.369, p < 0.01, respectively). TSH and FT4 were the only predictors of EPC counts.

CONCLUSIONS

Hypothyroidism is associated with low EPC counts. Treatment with LT4, but not Se, can improve EPC counts.

Clinical outcomes of patients with hypothyroidism undergoing percutaneous coronary intervention

AIMS

The aim of this study was to investigate the association between hypothyroidism and major adverse cardiovascular and cerebral events (MACCE) in patients undergoing percutaneous coronary intervention (PCI).

METHODS AND RESULTS

Two thousand four hundred and thirty patients who underwent PCI were included. Subjects were divided into two groups: hypothyroidism (n = 686) defined either as a history of hypothyroidism or thyroid-stimulating hormone (TSH) ≥5.0 mU/mL, and euthyroidism (n = 1744) defined as no history of hypothyroidism and/or 0.3 mU/mL ≤ TSH < 5.0 mU/mL. Patients with hypothyroidism were further categorized as untreated (n = 193), or those taking thyroid replacement therapy (TRT) with adequate replacement (0.3 mU/mL ≤ TSH < 5.0 mU/mL, n = 175) or inadequate replacement (TSH ≥ 5.0 mU/mL, n = 318). Adjusted hazard ratios (HRs) were calculated using Cox proportional hazards models. Median follow-up was 3.0 years (interquartile range, 0.5-7.0). After adjustment for covariates, the risk of MACCE and its constituent parts was higher in patients with hypothyroidism compared with those with euthyroidism (MACCE: HR: 1.28, P = 0.0001; myocardial infarction (MI): HR: 1.25, P = 0.037; heart failure: HR: 1.46, P = 0.004; revascularization: HR: 1.26, P = 0.0008; stroke: HR: 1.62, P = 0.04). Compared with untreated patients or those with inadequate replacement, adequately treated hypothyroid patients had a lower risk of MACCE (HR: 0.69, P = 0.005; HR: 0.78, P = 0.045), cardiac death (HR: 0.43, P = 0.008), MI (HR: 0.50, P = 0.0004; HR: 0.60, P = 0.02), and heart failure (HR: 0.50, P = 0.02; HR: 0.52, P = 0.017).

CONCLUSION

Hypothyroidism is associated with a higher incidence of MACCE compared with euthyroidism in patients undergoing PCI. Maintaining adequate control on TRT is beneficial in preventing MACCE.

Prognostic Role of Hypothyroidism in Heart Failure: A Meta-Analysis

Hypothyroidism is a risk factor of heart failure (HF) in the general population. However, the relationship between hypothyroidism and clinical outcomes in patients with established HF is still inconclusive.We conducted a systematic review and meta-analysis to clarify the association of hypothyroidism and all-cause mortality as well as cardiac death and/or hospitalization in patients with HF. We searched MEDLINE via PubMed, EMBASE, and Scopus databases for studies of hypothyroidism and clinical outcomes in patients with HF published up to the end of January 2015. Random-effects models were used to estimate summary relative risk (RR) statistics. We included 13 articles that reported RR estimates and 95% confidence intervals (95% CIs) for hypothyroidism with outcomes in patients with HF. For the association of hypothyroidism with all-cause mortality and with cardiac death and/or hospitalization, the pooled RR was 1.44 (95% CI: 1.29-1.61) and 1.37 (95% CI: 1.22-1.55), respectively. However, the association disappeared on adjustment for B-type natriuretic protein level (RR 1.17, 95% CI: 0.90-1.52) and in studies of patients with mean age <65 years (RR 1.23, 95% CI: 0.88-1.76).We found hypothyroidism associated with increased all-cause mortality as well as cardiac death and/or hospitalization in patients with HF. Further diagnostic and therapeutic procedures for hypothyroidism may be needed for patients with HF.

Thyroid functional disease: an under-recognized cardiovascular risk factor in kidney disease patients

Thyroid functional disease, and in particular hypothyroidism, is highly prevalent among chronic kidney disease (CKD) and end-stage renal disease (ESRD) patients. In the general population, hypothyroidism is associated with impaired cardiac contractility, endothelial dysfunction, atherosclerosis and possibly higher cardiovascular mortality. It has been hypothesized that hypothyroidism is an under-recognized, modifiable risk factor for the enormous burden of cardiovascular disease and death in CKD and ESRD, but this has been difficult to test due to the challenge of accurate thyroid functional assessment in uremia. Low thyroid hormone levels (i.e. triiodothyronine) have been associated with adverse cardiovascular sequelae in CKD and ESRD patients, but these metrics are confounded by malnutrition, inflammation and comorbid states, and hence may signify nonthyroidal illness (i.e. thyroid functional test derangements associated with underlying ill health in the absence of thyroid pathology). Thyrotropin is considered a sensitive and specific thyroid function measure that may more accurately classify hypothyroidism, but few studies have examined the clinical significance of thyrotropin-defined hypothyroidism in CKD and ESRD. Of even greater uncertainty are the risks and benefits of thyroid hormone replacement, which bear a narrow therapeutic-to-toxic window and are frequently prescribed to CKD and ESRD patients. In this review, we discuss mechanisms by which hypothyroidism adversely affects cardiovascular health; examine the prognostic implications of hypothyroidism, thyroid hormone alterations and exogenous thyroid hormone replacement in CKD and ESRD; and identify areas of uncertainty related to the interplay between hypothyroidism, cardiovascular disease and kidney disease requiring further investigation.

Subclinical hypothyroidism is associated with increased risk for cancer mortality in adult Taiwanese-a 10 years population-based cohort

BACKGROUND

The association between subclinical hypothyroidism (SCH) and cancer mortality is seldom discussed.

METHODS

A total of 115,746 participants without thyroid disease history, aged 20 and above, were recruited from four nationwide health screening centers in Taiwan from 1998 to 1999. SCH was defined as a serum thyroid-stimulating hormone (TSH) level of 5.0-19.96 mIU/L with normal total thyroxine concentrations. Euthyroidism was defined as a serum TSH level of 0.47-4.9 mIU/L. Cox proportional hazards regression analyses were used to estimate the relative risks (RRs) of death from cancer for adults with SCH during a 10-year follow-up period.

RESULTS

Among 115,746 adults, 1,841 had SCH (1.6%) and 113,905 (98.4%) had euthyroidism. There were 1,532 cancer deaths during the 1,034,082 person-years follow-up period. Adjusted for age, gender, body mass index, diabetes, hypertension, dyslipidemia, smoking, alcohol drinking, betel nut chewing, physical activity, income, and education level, the RRs (95% confidence interval) of cancer deaths among subjects with SCH versus euthyroid subjects were 1.51 (1.06 to 2.15). Cancer site analysis revealed a significant increased risk of bone, skin and breast cancer among SCH subjects (RR 2.79, (1.01, 7.70)). The risks of total cancer deaths were more prominent in the aged (RR 1.71, (1.02 to 2.87)), in females (RR 1.69 (1.08 to 2.65)), and in heavy smokers (RR 2.24, (1.19 to 4.21)).

CONCLUSIONS

Subjects with SCH had a significantly increased risk for cancer mortality among adult Taiwanese. This is the first report to demonstrate the association between SCH and cancer mortality.

Thyroid dysfunction associated with follicular cell steatosis in obese male mice and humans

Adult thyroid dysfunction is a common endocrine disorder associated with an increased risk of cardiovascular disease and mortality. A recent epidemiologic study revealed a link between obesity and increased prevalence of hypothyroidism. It is conceivable that excessive adiposity in obesity might lead to expansion of the interfollicular adipose (IFA) depot or steatosis in thyroid follicular cells (thyroid steatosis, TS). In this study, we investigated the morphological and functional changes in thyroid glands of obese humans and animal models, diet-induced obese (DIO), ob/ob, and db/db mice. Expanded IFA depot and TS were observed in obese patients. Furthermore, DIO mice showed increased expression of lipogenesis-regulation genes, such as sterol regulatory element binding protein 1 (SREBP-1), peroxisome proliferator-activated receptor γ (PPARγ), acetyl coenzyme A carboxylase (ACC), and fatty acid synthetase (FASN) in the thyroid gland. Steatosis and ultrastructural changes, including distension of the endoplasmic reticulum (ER) and mitochondrial distortion in thyroid follicular cells, were uniformly observed in DIO mice and genetically obese mouse models, ob/ob and db/db mice. Obese mice displayed a variable degree of primary thyroid hypofunction, which was not corrected by PPARγ agonist administration. We propose that systemically increased adiposity is associated with characteristic IFA depots and TS and may cause or influence the development of primary thyroid failure.

Duration of thyroid dysfunction correlates with all-cause mortality. the OPENTHYRO Register Cohort

Introduction and Aim

The association between thyroid dysfunction and mortality is controversial. Moreover, the impact of duration of thyroid dysfunction is unclarified. Our aim was to investigate the correlation between biochemically assessed thyroid function as well as dysfunction duration and mortality.

Methods

Register-based follow-up study of 239,768 individuals with a serum TSH measurement from hospitals and/or general practice in Funen, Denmark. Measurements were performed at a single laboratory from January 1st 1995 to January 1st 2011. Cox regression was used for mortality analyses and Charlson Comorbidity Index (CCI) was used as comorbidity score.

Results

Hazard ratios (HR) with 95% confidence intervals (CI) for mortality with decreased (<0.3 mIU/L) or elevated (>4.0 mIU/L) levels of TSH were 2.22; 2.14–2.30; P<0.0001 and 1.28; 1.22–1.35; P<0.0001, respectively. Adjusting for age, gender, CCI and diagnostic setting attenuated the risk estimates (HR 1.23; 95% CI: 1.19–1.28; P<0.0001, mean follow-up time 7.7 years, and HR 1.07; 95% CI: 1.02–1.13; P = 0.004, mean follow-up time 7.2 years) for decreased and elevated values of TSH, respectively. Mortality risk increased by a factor 1.09; 95% CI: 1.08–1.10; P<0.0001 or by a factor 1.03; 95% CI: 1.02–1.04; P<0.0001 for each six months a patient suffered from decreased or elevated TSH, respectively. Subdividing according to degree of thyroid dysfunction, overt hyperthyroidism (HR_overt 1.12; 95% CI: 1.06–1.19; P<0.0001), subclinical hyperthyroidism (HR_subclinical 1.09; 95% CI: 1.02–1.17; P = 0.02) and overt hypothyroidism (HR_overt 1.57; 95% CI: 1.34–1.83; P<0.0001), but not subclinical hypothyroidism (HR_subclinical 1.03; 95% CI: 0.97–1.09; P = 0.4) were associated with increased mortality.

Conclusions and Relevance

In a large-scale, population-based cohort with long-term follow-up (median 7.4 years), overt and subclinical hyperthyroidism and overt but not subclinical hypothyroidism were associated with increased mortality. Excess mortality with increasing duration of decreased or elevated serum TSH suggests the importance of timely intervention in individuals with thyroid dysfunction.

Subclinical and overt thyroid dysfunction and risk of all-cause mortality and cardiovascular events: a large population study

CONTEXT

Thyroid dysfunction has been associated with both increased all-cause and cardiovascular mortality, but limited data are available on mild thyroid dysfunction and cause-specific mortality.

OBJECTIVE

The objective of the study was to examine the risk of all-cause mortality, major adverse cardiovascular events (MACEs), and cause-specific events in subjects with overt and subclinical thyroid dysfunction.

DESIGN

This was a retrospective cohort study.

SETTING AND PARTICIPANTS

Participants in the study were subjects who underwent thyroid blood tests, without prior thyroid disease, consulting their general practitioner in 2000-2009 in Copenhagen, Denmark.

MAIN OUTCOME MEASURE

All-cause mortality, MACEs, and cause-specific events identified in nationwide registries were measured.

RESULTS

A total of 47 327 (8.4%) deaths occurred among 563 700 included subjects [mean age 48.6 (SD ± 18.2) y; 39% males]. All-cause mortality was increased in overt and subclinical hyperthyroidism [age adjusted incidence rates of 16 and 15 per 1000 person-years, respectively; incidence rate ratios (IRRs) 1.25 [95% confidence interval (CI) 1.15-1.36] and 1.23 (95% CI 1.16-1.30)] compared with euthyroid (incidence rate of 12 per 1000 person-years). Risk of MACEs was elevated in overt and subclinical hyperthyroidism [IRRs 1.16 (95% CI 1.05-1.27) and 1.09 (95% CI 1.02-1.16)] driven by heart failure [IRRs 1.14 (95% CI 0.99-1.32) and 1.20 (95% CI 1.10-1.31)]. A reduction of all-cause mortality was observed in subclinical hypothyroidism with TSH of 5-10 mIU/L [IRR 0.92 (95% CI 0.86-0.98)].

CONCLUSIONS

Heart failure is the leading cause of an increased cardiovascular mortality in both overt and subclinical hyperthyroidism. Subclinical hypothyroidism with TSH 5-10 mIU/L might be associated with a lower risk of all-cause mortality.

Treatment with thyroid hormone

Thyroid hormone deficiency can have important repercussions. Treatment with thyroid hormone in replacement doses is essential in patients with hypothyroidism. In this review, we critically discuss the thyroid hormone formulations that are available and approaches to correct replacement therapy with thyroid hormone in primary and central hypothyroidism in different periods of life such as pregnancy, birth, infancy, childhood, and adolescence as well as in adult patients, the elderly, and in patients with comorbidities. Despite the frequent and long term use of l-T4, several studies have documented frequent under- and overtreatment during replacement therapy in hypothyroid patients. We assess the factors determining l-T4 requirements (sex, age, gender, menstrual status, body weight, and lean body mass), the major causes of failure to achieve optimal serum TSH levels in undertreated patients (poor patient compliance, timing of l-T4 administration, interferences with absorption, gastrointestinal diseases, and drugs), and the adverse consequences of unintentional TSH suppression in overtreated patients. Opinions differ regarding the treatment of mild thyroid hormone deficiency, and we examine the recent evidence favoring treatment of this condition. New data suggesting that combined therapy with T3 and T4 could be indicated in some patients with hypothyroidism are assessed, and the indications for TSH suppression with l-T4 in patients with euthyroid multinodular goiter and in those with differentiated thyroid cancer are reviewed. Lastly, we address the potential use of thyroid hormones or their analogs in obese patients and in severe cardiac diseases, dyslipidemia, and nonthyroidal illnesses.

Increased psychiatric morbidity before and after the diagnosis of hypothyroidism: a nationwide register study

BACKGROUND

Thyroid hormones are necessary for fetal brain development, and hypothyroidism in adults has been associated with mood symptoms and reduced quality of life. Nevertheless, our knowledge regarding the association and temporal relation between hypothyroidism and mental disorders is ambiguous. Our objective was to investigate, at a nationwide level, whether a diagnosis of hypothyroidism is associated with psychiatric morbidity.

METHODS

This is an observational cohort study. On the basis of record linkage between different Danish health registers, 2822 hypothyroid singletons each matched with 4 nonhypothyroid controls were identified and followed over a mean period of 6 years (range 1-13). Additionally, we included 385 same-sex twin pairs discordant for hypothyroidism. Diagnoses of psychiatric disorders as well as treatment with antidepressants, antipsychotics, and anxiolytics were recorded. Logistic and cox regression models were used to assess the risk of psychiatric morbidity before and after the diagnosis of hypothyroidism, respectively.

RESULTS

Before the diagnosis of hypothyroidism, such individuals had an increased prevalence of diagnoses with psychiatric disorders (odds ratio, OR, 1.51; 95% confidence interval [CI 1.12-2.04]) and increased prevalence of treatment with antipsychotics (OR 1.49 [CI 1.29-1.73]), antidepressants (OR 1.50 [CI 1.35-1.67]), and anxiolytics (OR 1.28 [CI 1.16-1.41]). After the diagnosis of hypothyroidism, patients had a higher risk of being diagnosed with a psychiatric disorder (hazard ratio, HR, 2.40 [CI 1.81-3.18]), and an increased risk of being treated with antidepressants (HR 1.30 [CI 1.15-1.47]) and anxiolytics (HR 1.27 [CI 1.10-1.47]), but not antipsychotics (HR 1.13 [CI 0.91-1.41]). On the basis of the twin data, we could not demonstrate genetic confounding.

CONCLUSIONS

Subjects with hypothyroidism have an increased risk of being diagnosed with a psychiatric disorder as well as being treated with antidepressants, antipsychotics, and anxiolytics both before and after the diagnosis of hypothyroidism.

The chronic autoimmune thyroiditis quality of life selenium trial (CATALYST): study protocol for a randomized controlled trial

BACKGROUND

Patients with chronic autoimmune thyroiditis have impaired health-related quality of life. The thyroid gland has a high selenium concentration, and specific selenoprotein enzyme families are crucial to immune function, and catalyze thyroid hormone metabolism and redox processes in thyroid cells. Previous randomized controlled trials have found that selenium supplementation decreases thyroid-disease-specific antibody levels. We hypothesize that selenium might be beneficial in the treatment of chronic autoimmune thyroiditis.

METHODS/DESIGN

The CATALYST trial is an investigator-initiated randomized, blinded, multicentre clinical trial of selenium supplementation versus placebo in patients with chronic autoimmune thyroiditis.

INCLUSION CRITERIA

age ≥18 years; serum thyroid peroxidase antibody level ≥100 IU/ml within the previous 12 months; treatment with levothyroxine and written informed consent.

EXCLUSION CRITERIA

previous diagnosis of toxic nodular goitre, Graves' hyperthyroidism, postpartum thyroiditis, Graves' orbitopathy; previous antithyroid drug treatment, radioiodine therapy or thyroid surgery; immune-modulatory or other medication affecting thyroid function; pregnancy, planned pregnancy or breastfeeding; allergy towards any intervention or placebo component; intake of selenium supplementation >55 μg/day; inability to read or understand Danish or lack of informed consent. The trial will include 2 × 236 participants. The experimental intervention and control groups will receive 200 μg selenium-enriched yeast or matching placebo tablets daily for 12 months. The experimental supplement will be SelenoPrecise®. The primary outcome is thyroid-related quality of life assessed by the Thyroid Patient-Reported Outcome (ThyPRO) questionnaire. Secondary outcomes include serum thyroid peroxidase antibody concentration; serum triiodothyronine/thyroxine ratio; levothyroxine dosage; adverse reactions and serious adverse reactions and events.

DISCUSSION

In this pragmatic trial, participating patients follow their usual treatment at their usual hospitals. In order to collect high-quality data on the clinical course and quality of life, and to minimize missing data, an elaborate trial management system has been designed. 12 months intervention duration was selected in consideration of the primary outcome, thyroid-related quality of life.

TRIAL REGISTRATION

ClinicalTrials.gov ID: NCT02013479.

Vascular smooth muscle cell apoptosis is an early trigger for hypothyroid atherosclerosis

AIMS

Endothelial dysfunction is an initial and vascular smooth muscle cell (VSMC) apoptosis, a later step of atherosclerosis. Hypothyroidism accelerates atherosclerosis. However, the early events responsible for this pro-atherosclerotic effect are unclear.

METHODS AND RESULTS

Rats were resistant to induction of atherosclerosis by high cholesterol diet alone, but became susceptible in hypothyroid state achieved by administration of propylthiouracil (PTU) for 6 weeks. VSMC dysfunction and apoptosis were obvious within 1 week after PTU treatment, without signs of endothelial dysfunction. This early VSMC damage was caused by hypothyroidism but not the high cholesterol diet. In ApoE knockout mice, PTU-induced hypothyroidism triggered early VSMC apoptosis, increased oxidative stress, and accelerated atherosclerosis development. Thyroid hormone supplementation (T4, 10, or 50 μg/kg) prevented atherogenic phenotypes in hypothyroid rats and mice. In rats, thyroidectomy caused severe hypothyroidism 5 days after operation, which also led to rapid VSMC dysfunction and apoptosis. In vitro studies did not show a direct toxic effect of PTU on VSMCs. In contrast, thyroid hormone (T3, 0.75 μg/L plus T4, 50 nmol/L) exerted a direct protection against VSMC apoptosis, which was reduced by knockdown of TRα1, rather than TRβ1 and TRβ2 receptors. TRα1-mediated inhibition of apoptotic signalling of JNKs and caspase-3 contributed to the anti-apoptotic action of thyroid hormone.

CONCLUSION

These findings provide an in vivo example for VSMC apoptosis as an early trigger of hypothyroidism-associated atherosclerosis, and reveal activation of TRα1 receptors to prevent VSMC apoptosis as a therapeutic strategy in this disease.

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

BACKGROUND

Hypothyroidism has been linked with an increased risk of other morbidities, such as cardiovascular diseases and diabetes mellitus. However, the temporal relationship between these diseases and the diagnosis of hypothyroidism is not well illuminated. Such information may provide insight into causal relationships between hypothyroidism and other morbidities.

AIM

To investigate the type and extent of somatic morbidity before and after a diagnosis of hypothyroidism.

METHODS

Observational cohort study. From official Danish health registers, 2822 hypothyroid singletons were identified and matched 1:4 with non-hypothyroid controls and observed over a mean period of 6 years. Frequency of different morbidities was obtained by person-to-person linking in the registers. Logistic and Cox regression models were used to assess the risk of morbidity before and after the diagnosis of hypothyroidism, respectively.

RESULTS

Prior to the diagnosis of hypothyroidism there was a significantly increased risk of being diagnosed with cardiovascular diseases (odds ratio (OR) 1.37; 95% confidence interval (CI): 1.19-1.58), lung diseases (OR 1.25; 95% CI: 1.13-1.39), diabetes mellitus (OR 1.92; 95% CI: 1.61-2.29), as well as malignant diseases (OR 1.24; 95% CI: 1.06-1.45). Following the diagnosis of hypothyroidism there was a significantly increased risk of being diagnosed with cardiovascular diseases (hazard ratio (HR) 1.36; 95% CI: 1.15-1.60); lung diseases (HR 1.51; 95% CI: 1.30-1.75); and diabetes mellitus (HR 1.40; 95% CI: 1.11-1.77).

CONCLUSIONS

Prior to the diagnosis of hypothyroidism there is an excess risk of being diagnosed with cardiovascular diseases, lung diseases, diabetes mellitus, and malignant diseases. Following the diagnosis of hypothyroidism we demonstrate an increased frequency of cardiovascular diseases, lung diseases, and diabetes mellitus.

Hypothyroidism after primary radiotherapy for head and neck squamous cell carcinoma: normal tissue complication probability modeling with latent time correction

BACKGROUND AND PURPOSE

To develop a normal tissue complication probability (NTCP) model of radiation-induced biochemical hypothyroidism (HT) after primary radiotherapy for head and neck squamous cell carcinoma (HNSCC) with adjustment for latency and clinical risk factors.

PATIENTS AND METHODS

Patients with HNSCC receiving definitive radiotherapy with 66-68Gy without surgery were followed up with serial post-treatment thyrotropin (TSH) assessment. HT was defined as TSH >4.0mU/l. Data were analyzed with both a logistic and a mixture model (correcting for latency) to determine risk factors for HT and develop an NTCP model based on mean thyroid dose (MTD) and thyroid volume.

RESULTS

203 patients were included. Median follow-up: 25.1months. Five-year estimated risk of HT was 25.6%. In the mixture model, the only independent risk factors for HT were thyroid volume (cm(3)) (OR=0.75 [95% CI: 0.64-0.85], p<0.001) and MTD (Gy) (OR=1.12 [95% CI: 1.07-1.20], p<0.001). From the mixture NTCP-model individual dose constraints for a 25% risk of HT were 26, 38, 48 and 61Gy for thyroid volumes of 10, 15, 20 and 25cm(3), respectively.

CONCLUSIONS

Comparing the logistic and mixture models demonstrates the importance of latent-time correction in NTCP-modeling. Thyroid dose constraints in treatment planning should be individualized based on thyroid volume.

Morbidity before and after the diagnosis of hyperthyroidism: a nationwide register-based study

BACKGROUND

Hyperthyroidism has been linked with different morbidities, like atrial fibrillation, stroke and diabetes mellitus. However, our knowledge regarding the extent and temporal relation between hyperthyroidism and other diseases is fragmented. Here, we aimed at evaluating various morbidities before and after the diagnosis of hyperthyroidism.

METHODS

Observational cohort study. From nationwide Danish health registers 2631 hyperthyroid singletons and 375 twin pairs discordant for hyperthyroidism were identified and followed for an average of 6 years (range 0-13). Data on the occurrence of cardiovascular diseases, lung diseases, diabetes mellitus, rheumatic diseases and malignant diseases was obtained by person-to-person record linkage with the National Danish Patient Register and/or the Danish National Prescription Registry (lung diseases and diabetes mellitus). Logistic and Cox regression models were used to assess the risk of morbidity before and after the diagnosis of hyperthyroidism, respectively. All Cox regression analyses were adjusted for the degree of co-morbidity preceding the diagnosis of hyperthyroidism, using the Charlson score.

RESULTS

Hyperthyroid individuals had a significantly higher risk of being diagnosed with cardiovascular diseases (odds ratio (OR) 1.65; 95% confidence interval (CI): 1.45-1.87), lung diseases (OR 1.53; 95% CI: 1.29-1.60), and diabetes mellitus (OR 1.43, 95% CI: 1.20-1.72), but not with malignant diseases (OR 1.16, 95% CI: 0.99-1.36) prior to the diagnosis of hyperthyroidism. After the diagnosis of hyperthyroidism, subjects had a significantly higher risk of being diagnosed with cardiovascular diseases (hazard ratio (HR) 1.34; 95% CI: 1.15-1.56), lung diseases (HR 1.28; 95% CI: 1.10-1.49), and diabetes mellitus (HR 1.46; 95% CI: 1.16-1.84), but not with rheumatic diseases (HR 1.39, 95% CI: 0.92-2.09) or malignant diseases (HR 1.18, 95% CI 0.97-1.42).

CONCLUSIONS

We demonstrate a significantly increased burden of morbidity, both before and after the diagnosis of hyperthyroidism.

Subclinical hypothyroidism and survival: the effects of heart failure and race

CONTEXT

Studies examining the association between subclinical hypothyroidism and mortality have yielded conflicting results. Emerging data suggest these associations may depend upon underlying congestive heart failure (CHF) and/or race, but this has not been empirically determined.

OBJECTIVE

Our objective was to examine the association between subclinical hypothyroidism and hypothyroidism overall with mortality according to pre-existing CHF and race.

DESIGN AND PARTICIPANTS

We examined the associations of subclinical hypothyroidism (TSH higher than assay upper limit of normal; total T4 within reference) and hypothyroidism overall (TSH higher than assay upper limit of normal; total T4 below lower limit of normal or within reference) with all-cause mortality among Third National Health and Nutrition Examination Survey participants stratified by CHF and race using multivariable Cox models. To confirm whether differences between strata were statistically significant, we tested for interaction on the basis of CHF (separately) and race by likelihood ratio testing.

RESULTS

There were 14 130 (95.0%) euthyroid controls and 749 (5.0%) participants with hypothyroidism, 691 (4.6%) of whom had subclinical disease. Subclinical hypothyroidism vs euthyroidism was associated with greater mortality in those with CHF but not in those without: adjusted hazard ratios (HRs) (95% confidence intervals [CIs]) = 1.44 (1.01-2.06) and 0.97 (0.85-1.11), respectively (P interaction = .03). Similar findings were observed for hypothyroidism overall. Hypothyroidism overall vs euthyroidism was associated with greater mortality in Black participants (HR = 1.44 [95% CI = 1.03-2.03]) but not in non-Blacks (HR = 0.95 [95% CI = 0.83-1.08]) (P interaction = .03).

CONCLUSION

Among participants with CHF, subclinical hypothyroidism and hypothyroidism overall are associated with greater death risk. Additional studies are needed to confirm findings and explore possible mechanisms for the differential hypothyroidism-mortality association across race.

Excess mortality in patients diagnosed with hypothyroidism: a nationwide cohort study of singletons and twins

BACKGROUND

Although hypothyroidism is associated with increased morbidity, an association with increased mortality is still debated. Our objective was to investigate, at a nationwide level, whether a diagnosis of hypothyroidism influences mortality.

METHODS

In an observational cohort study from January 1, 1978 until December 31, 2008 using record-linkage data from nationwide Danish health registers, 3587 singletons and 682 twins diagnosed with hypothyroidism were identified. Hypothyroid individuals were matched 1:4 with nonhypothyroid controls with respect to age and gender and followed over a mean period of 5.6 years (range 0-30 years). The hazard ratio (HR) for mortality was calculated using Cox regression analyses. Comorbidity was evaluated using the Charlson score (CS).

RESULTS

In singletons with hypothyroidism, the mortality risk was increased (HR 1.52; 95% confidence interval [CI]: 1.41-1.65). Although the effect attenuated, hypothyroidism remained associated with increased mortality when evaluating subjects with a CS = 0 (HR 1.23; 95% CI: 1.05-1.44). In twin pairs discordant for hypothyroidism, the hypothyroid twin had excess mortality compared with the corresponding euthyroid cotwin (HR 1.40; 95% CI 0.95-2.05). However, after stratifying for zygosity, hypothyroidism was associated with excess mortality in dizygotic twin pairs (HR 1.61; 95% CI 1.00-2.58), whereas the association attenuated in monozygotic pairs (HR 1.06; 95% CI 0.55-2.05).

CONCLUSIONS

Hypothyroidism is associated with an excess mortality of around 50%, which to some degree is explained by comorbidity. In addition, the finding of an association between hypothyroidism and mortality within disease discordant dizygotic but not monozygotic twin pairs indicates that the association between hypothyroidism and mortality is also influenced by genetic confounding.

The thyroid--too much and too little across the ages. The consequences of subclinical thyroid dysfunction

Mild thyroid dysfunction is common, and more prevalent than overt hyper- and hypothyroidism. Subclinical (mild) thyroid dysfunction is a biochemical entity characterized by an abnormality of serum TSH associated with normal serum thyroid hormone concentrations. Subclinical hyperthyroidism is thus defined as low or suppressed serum TSH with normal serum-free T4 and T3, while subclinical hypothyroidism is defined as raised serum TSH with normal circulating T4. These biochemical abnormalities are part of the much wider spectrum of thyroid dysfunction which includes overt hyperthyroidism and overt hypothyroidism, but by no means always indicate underlying thyroid disease. There is much debate about the significance of mild abnormalities of thyroid function in terms of symptoms and potential associations with long-term morbidity and mortality and hence much debate about whether to screen for these abnormalities, and, once identified, whether to treat or monitor, and if so, how? Our knowledge base has increased significantly in recent years, principally because studies of large cohorts have begun to define the epidemiology and associations of mild thyroid dysfunction (including short-term and long-term outcomes) and a small but increasing number of randomized-controlled intervention studies have been reported. There is, however, much to learn about these disorders and, given their prevalence, their impact on health.

Radioiodine therapy in benign thyroid diseases: effects, side effects, and factors affecting therapeutic outcome

Radioiodine ((131)I) therapy of benign thyroid diseases was introduced 70 yr ago, and the patients treated since then are probably numbered in the millions. Fifty to 90% of hyperthyroid patients are cured within 1 yr after (131)I therapy. With longer follow-up, permanent hypothyroidism seems inevitable in Graves' disease, whereas this risk is much lower when treating toxic nodular goiter. The side effect causing most concern is the potential induction of ophthalmopathy in predisposed individuals. The response to (131)I therapy is to some extent related to the radiation dose. However, calculation of an exact thyroid dose is error-prone due to imprecise measurement of the (131)I biokinetics, and the importance of internal dosimetric factors, such as the thyroid follicle size, is probably underestimated. Besides these obstacles, several potential confounders interfere with the efficacy of (131)I therapy, and they may even interact mutually and counteract each other. Numerous studies have evaluated the effect of (131)I therapy, but results have been conflicting due to differences in design, sample size, patient selection, and dose calculation. It seems clear that no single factor reliably predicts the outcome from (131)I therapy. The individual radiosensitivity, still poorly defined and impossible to quantify, may be a major determinant of the outcome from (131)I therapy. Above all, the impact of (131)I therapy relies on the iodine-concentrating ability of the thyroid gland. The thyroid (131)I uptake (or retention) can be stimulated in several ways, including dietary iodine restriction and use of lithium. In particular, recombinant human thyrotropin has gained interest because this compound significantly amplifies the effect of (131)I therapy in patients with nontoxic nodular goiter.

Excess mortality in hyperthyroidism: the influence of preexisting comorbidity and genetic confounding: a danish nationwide register-based cohort study of twins and singletons

CONTEXT

Hyperthyroidism is associated with severe comorbidity, such as stroke, and seems to confer increased mortality. However, it is unknown whether this increased mortality is explained by hyperthyroidism per se, comorbidity, and/or genetic confounding.

OBJECTIVE

The objective of the study was to investigate whether hyperthyroidism is associated with an increased mortality and, if so, whether the association is influenced by comorbidity and/or genetic confounding.

METHODS

This was an observational cohort study using record-linkage data from nationwide Danish health registers. We identified 4850 singletons and 926 twins from same-sex pairs diagnosed with hyperthyroidism. Each case was matched with four controls for age and gender. The Charlson score was calculated from discharge diagnoses on an individual level to measure comorbidity. Cases and controls were followed up for a mean of 10 yr (range 0-31 yr), and the hazard ratio (HR) for mortality was calculated using Cox regression analyses.

RESULTS

In singletons there was a significantly higher mortality in individuals diagnosed with hyperthyroidism than in controls [HR 1.37; 95% confidence interval (CI) 1.30-1.46]. This persisted after adjustment for preexisting comorbidity (HR 1,28; 95% CI 1.21-1.36). In twin pairs discordant for hyperthyroidism (625 pairs), the twin with hyperthyroidism had an increased mortality compared with the corresponding cotwin (HR 1.43; 95% CI 1.09-1.88). However, this was found only in dizygotic pairs (HR 1.80; 95% CI 1.27-2.55) but not in monozygotic pairs (HR 0.95; 95% CI 0.60-1.50).

CONCLUSIONS

Hyperthyroidism is associated with an increased mortality independent of preexisting comorbidity. The study of twin pairs discordant for hyperthyroidism suggests that genetic confounding influences the association between hyperthyroidism and mortality.

Is Thyroid Autoimmunity per se a Determinant of Quality of Life in Patients with Autoimmune Hypothyroidism?

PURPOSE

To evaluate the relationship between thyroid variables and health-related quality of life (QoL) in patients with autoimmune hypothyroidism, using the thyroid-specific QoL questionnaire ThyPRO.

METHODS

In a cross-sectional study, responses to the ThyPRO from 199 outpatients with autoimmune hypothyroidism were analyzed in relation to thyroid volume, thyroid function and markers of thyroid autoimmunity. Based on a classical QoL framework, we hypothesized that physiological dysfunction caused specific physical and psychological symptoms, which affected functioning and well-being, and consequently participation in life and QoL. These hypotheses were tested through multiple regression and multivariate path analysis models.

RESULTS

None of the thyroid function tests were associated with QoL scores. However, in the pairwise regression, the thyroid peroxidase antibody (TPOAb) level was associated with several QoL outcomes: Goitre Symptoms (p = 0.024), Depressivity (p = 0.004), Anxiety (p = 0.004), Emotional Susceptibility (p = 0.005) and Impaired Social Life (p = 0.047). In the multivariate model, the TPOAb level was related to Goitre Symptoms (r = 0.17, p = 0.019), Depressivity (r = 0.24, p = 0.001), and Anxiety (r = 0.23, p = 0.002), but no longer to Emotional Susceptibility or Impaired Social Life, indicating that the effect on these were mediated through an effect on the symptom scales (i.e. Goitre Symptoms, Depressivity and Anxiety).

CONCLUSION

Health-related QoL, evaluated with state-of-the-art QoL methodology, was related to TPOAb level but not to thyroid function. This raises the hypothesis that autoimmunity, independent of thyroid function, impacts on QoL in patients with autoimmune hypothyroidism, especially in terms of psychological symptoms. Longitudinal studies, in initially untreated patients, are needed to test this hypothesis.