The clinical significance of subclinical thyroid dysfunction

Thyroid nodules and differentiated thyroid cancer: update on the Brazilian consensus

Thyroid nodules are frequent findings, especially when sensitive imaging methods are used. Although thyroid cancer is relatively rare, its incidence is increasing, particularly in terms of small tumors, which have an uncertain clinical relevance. Most patients with differentiated thyroid cancer exhibit satisfactory clinical outcomes when treatment is appropriate, and their mortality rate is similar to that of the overall population. However, relapse occurs in a considerable fraction of these patients, and some patients stop responding to conventional treatment and eventually die from their disease. Therefore, the challenge is how to identify the individuals who require more aggressive disease management while sparing the majority of patients from unnecessary treatments and procedures. We have updated the Brazilian Consensus that was published in 2007, emphasizing the diagnostic and therapeutic advances that the participants, representing several Brazilian university centers, consider most relevant in clinical practice. The formulation of the present guidelines was based on the participants' experience and a review of the relevant literature.

Thyroid hormone replacement therapy attenuates the decline of renal function in chronic kidney disease patients with subclinical hypothyroidism

BACKGROUND

Subclinical hypothyroidism (SCH) is not a rare condition in females, the elderly, or patients with chronic kidney disease (CKD). Even though previous studies have demonstrated that thyroid hormone replacement therapy (THRT) improves cardiac function and dyslipidemia in patients with SCH, it remains unclear as to whether THRT can improve renal function in CKD patients with SCH. This study investigated the impact of THRT on changes in estimated glomerular filtration rates (eGFR) in this patient population.

METHODS

A total of 113 CKD patients with SCH who were treated with L-thyroxine and had eGFR available for at least 24 months before and after THRT were enrolled between January 2005 and December 2011. A linear mixed model was used to compare patients' clinical and biochemical parameters at various time points. The slope of the decline in eGFR over time, both before and after THRT, was also calculated and compared using a linear mixed model.

RESULTS

The mean age of the study participants was 63.2±12.7 years, and 36 patients (31.9%) were men. The mean follow-up duration before and after THRT was 28.6±4.5 and 30.6±6.4 months respectively. After 24 months of THRT, serum thyrotropin (TSH) levels were significantly reduced-8.86±0.49 versus 1.41±0.73 μIU/mL, p<0.001-but there were no significant changes in triiodothyronine and free thyroxine concentrations. Serum albumin, calcium, phosphate, cholesterol, and triglyceride levels were also comparable before and after THRT. The rates of decline in eGFR were significantly attenuated by THRT (-4.31±0.51 vs.-1.08±0.36 [mL/min]/[year·1.73 m²], p<0.001), even after adjustment for age, sex, diabetes, mean arterial pressure, and serum albumin, cholesterol, and triglyceride concentrations (p<0.001).

CONCLUSION

THRT attenuated the rate of decline in renal function in CKD patients with SCH, suggesting that THRT may delay reaching end-stage renal disease in these patients.

Nanotoxicity: a growing need for study in the endocrine system

Nanomaterials (NMs) are engineered for commercial purposes such as semiconductors, building materials, cosmetics, and drug carriers, while natural nanoparticles (NPs) already exist in the environment. Due to their unique physicochemical properties, they may interact actively with biological systems. Some of these interactions might be detrimental to human health, and therefore studies on the potential 'nanotoxicity' of these materials in different organ systems are warranted. The purpose of developing the concept of nanotoxicity is to recognize and evaluate the hazards and risks of NMs and evaluate safety. This review will summarize and discuss recent reports derived from cell lines or animal models concerning the effects of NMs on, and their application in, the endocrine system of mammalian and other species. It will present an update on current studies of the effects of some typical NMs-such as metal-based NMs, carbon-based NMs, and dendrimers-on endocrine functions, in which some effects are adverse or unwanted and others are favorable or intended. Disruption of endocrine function is associated with adverse health outcomes including reproductive failure, metabolic syndrome, and some types of cancer. Further investigations are therefore required to obtain a thorough understanding of any potential risk of pathological endocrine disruption from products containing NMs. This review aims to provide impetus for further studies on the interactions of NMs with endocrine functions.

The Use of TSH in Determining Thyroid Disease: How Does It Impact the Practice of Medicine in Pregnancy?

During the last four decades, there have been considerable advances in the efficacy and precision of serum thyroid function testing. The development of the third generation assays for the measurement of serum thyroid stimulating hormone (TSH, thyrotropin) and the log-linear relationship with free thyroxine (T4) established TSH as the hallmark of thyroid function testing. While it is widely accepted that TSH outside of the normal range is consistent with thyroid dysfunction, a vast multitude of additional factors must be considered before an accurate clinical diagnosis can be made. This is especially important during pregnancy, when the thyroid is under considerable additional pregnancy-related demands requiring significant maternal physiological changes. This paper examines serum TSH measurement in pregnancy and some associated potential confounding factors.

Treatment of iron-deficiency anemia in patients with subclinical hypothyroidism

OBJECTIVE

Subclinical hypothyroidism is a health state that is associated with hypercholesterolemia, infertility, iron-deficiency anemia, and poor obstetric outcome. This article summarizes the results of a prospective clinical investigation of whether treatment of subclinical hypothyroidism and iron-deficiency anemia with a combination of levothyroxine plus iron salt would be superior to each treatment alone.

METHODS

In a randomized, double-blind, active-controlled trial, 60 patients with subclinical hypothyroidism and iron-deficiency anemia received iron salt+placebo (20 patients), levothyroxine+placebo (20 patients), or levothyroxine+iron salt (20 patients) for 3 months. Change from baseline (before) to end of study (after) in hemoglobin, ferritin, and thyroid-stimulating hormone levels were compared among groups.

RESULTS

The increase from baseline in hemoglobin and ferritin in the levothyroxine+iron group was superior to the other groups, in which a decrease in thyroid-stimulating hormone in the 2 groups that received levothyroxine was superior to the group treated with iron salt.

CONCLUSION

Subclinical hypothyroidism was investigated in iron-deficient patients with no acceptable response to iron salt alone. A combination of levothyroxine and iron salt is better than each one alone.

How selective are the new guidelines for treatment of subclinical hypothyroidism for patients with thyrotropin levels at or below 10 mIU/L?

BACKGROUND

By consensus, a thyrotropin (TSH) level persistently >10 mIU/L is an indication for the treatment of subclinical hypothyroidism (SCH). Controversy exists regarding patients whose TSH level is elevated but <10 mIU/L. Recently, the American Thyroid Association (ATA) and the American Association of Clinical Endocrinologists (AACE) published their position about factors that should be considered in the decision on treating SCH. This study evaluated the frequency of these factors among adult (non-pregnant) women with SCH whose TSH levels are ≤10 mIU/L.

METHODS

The presence of the conditions that should be considered for the treatment of SCH according to ATA and AACE was evaluated in 252 women who were diagnosed with SCH and had TSH levels ≤10 mIU/L. Pregnant women were excluded.

RESULTS

Antithyroperoxidase antibodies (TPOAbs) were detected in 137 (54.3%) women. A high cardiovascular risk was observed in 43 (17%) women. Eighty (31.7%) women who were not at high cardiovascular risk presented at least one classical risk factor (arterial hypertension, elevated level of low-density lipoprotein-cholesterol or low level of high-density lipoprotein-cholesterol, smoking, or first-degree family history of premature coronary artery disease). At least one symptom or sign of hypothyroidism that could not be explained by another condition was observed in 180 (71.4%) women. Two hundred thirty-two (92%) women had positive TPOAbs, or at least one classical cardiovascular risk factor, or at least one symptom or sign of hypothyroidism.

CONCLUSIONS

According to the new ATA and AACE guidelines, L-T4 therapy would be considered for 92% of women with SCH and TSH ≤10 mIU/L.

Patient-reported outcomes in adequately treated hypothyroidism - insights from the German versions of ThyDQoL, ThySRQ and ThyTSQ

BACKGROUND

Disease-specific patient-reported outcome measures (PROMs) have been developed as important research tools in the study of various diseases. For hypothyroidism there exist three validated disease-specific questionnaires in English: the Thyroid-Dependent Quality of Life Questionnaire (ThyDQoL), the Underactive Thyroid Symptom Rating Questionnaire (ThySRQ) and the Thyroid Treatment Satisfaction Questionnaire (ThyTSQ). We report psychometric properties of new German versions of the questionnaires including construct validity from two independent samples.

METHODS

230 envelopes with ThyDQoL, ThySRQ and ThyTSQ were given out to patients receiving levothyroxine for diagnosed hypothyroidism. Reliability and factor analyses were performed, correlations and hypothesised subgroup differences calculated to assess psychometric properties. Independently, 18 patients with treated hypothyroidism for autoimmune thyroiditis (Hashimoto’s disease) and 18 healthy control subjects were enrolled in a clinical study. Participants filled in the above questionnaires alongside well-known generic PROMs, e.g. the Beck Depression Inventory, the 12-item Well-Being Questionnaire and the Short-Form-36. Two blood samples were taken. Groups were compared and correlations between disease-specific and generic instruments analysed. Relationships between PROMs and biochemically determined thyroid hormone status were investigated.

RESULTS

102 patients returned completed questionnaires (response rate 44%). The newly translated questionnaires had satisfactory psychometric properties. Cronbach’s alpha was 0.92 for ThyDQoL, 0.81 for ThySRQ and 0.86 for ThyTSQ. For each of the questionnaires, a single factor structure explained the data best. Adequately treated patients with thyroid stimulating hormone levels in the upper normal range reported more symptoms in the ThySRQ. Those with autoimmune hypothyroidism reported being more bothered by depressive symptoms. Within the clinical sample, correlation with well-known generic instruments revealed good construct validity. In the clinical sample patients reported more symptoms in the ThySRQ, being more bothered by tiredness, higher depression and reduced well-being despite biochemically adequate treatment. Correlations between PROMs and biochemical thyroid hormone status revealed moderate though consistent associations.

CONCLUSIONS

Psychometric properties including construct validity of German versions of the ThyDQoL, ThySRQ and ThyTSQ are satisfactory. Feasibility and sensitivity in a clinical sample could be shown. We encourage the use of disease-specific PROMs in future studies as important additions to generic instruments in clinical research on hypothyroidism.

Thyroid dysfunction in the elderly

Thyroid dysfunction is common in the general population, and mild or subclinical forms can be present in more than 10% of individuals aged >80 years. The diagnosis of abnormal thyroid hormone concentrations in people aged >60 years poses a challenge, as the clinical presentation of thyroid dysfunction is usually nonspecific, and ageing is associated with a number of physiological changes that can affect thyroid function test results. Furthermore, the presence of acute or chronic nonthyroidal illnesses and the use of medications that interfere with thyroid function tests are common confounders in the determination of thyroid status in the elderly. Early diagnosis and treatment of overt thyroid dysfunction is crucial in this population in view of the marked effects of abnormal circulating thyroid hormone levels on a number of organ systems, including the heart, the skeleton and the neurological system. The clinical significance of mild thyroid overactivity and underactivity remains uncertain, and the need for treatment of subclinical thyroid dysfunction is much debated. A number of large epidemiological studies have identified associations between mild thyroid dysfunction and short-term as well as long-term adverse outcomes, and a small but increasing number of randomized controlled intervention studies have been reported. Guidelines recommend treatment of thyroid dysfunction on the basis of the degree of abnormal serum TSH concentrations, patient age and associated comorbidities. This Review describes the current evidence on the prevalence, diagnosis, management and long-term consequences of thyroid dysfunction in the elderly.

Consenso brasileiro para a abordagem clínica e tratamento do hipotireoidismo subclínico em adultos: recomendações do Departamento de Tireoide da Sociedade Brasileira de Endocrinologia e Metabologia

INTRODUÇÃO: O hipotireoidismo subclínico (HSC), definido por concentrações elevadas do TSH em face de níveis normais dos hormônios tireoidianos, tem elevada prevalência no Brasil, particularmente entre mulheres e idosos. Embora um número crescente de estudos venha associando o HSC com maior risco de doença arterial coronariana e de mortalidade, não há ensaio clínico randomizado sobre o benefício do tratamento com levotiroxina na redução dos riscos e o tratamento permanece controverso. OBJETIVO: Este consenso, patrocinado pelo Departamento de Tireoide da Sociedade Brasileira de Endocrinologia e Metabologia e desenvolvido por especialistas brasileiros com vasta experiência clínica em tireoide, apresenta recomendações baseadas em evidências para uma abordagem clínica do paciente com HSC no Brasil. MATERIAIS E MÉTODOS: Após estruturação das questões clínicas, a busca das evidências disponíveis na literatura foi realizada inicialmente na base de dados do MedLine-PubMed e posteriormente nas bases Embase e SciELO - Lilacs. A força da evidência, avaliada pelo sistema de classificação de Oxford, foi estabelecida a partir do desenho de estudo utilizado, considerando-se a melhor evidência disponível para cada questão e a experiência brasileira. RESULTADOS: Os temas abordados foram definição e diagnóstico, história natural, significado clínico, tratamento e gestação, que resultaram em 29 recomendações para a abordagem clínica do paciente adulto com HSC. CONCLUSÃO: O tratamento com levotiroxina foi recomendado para todos os pacientes com HSC persistente com níveis séricos do TSH > 10 mU/L e para alguns subgrupos especiais de pacientes.

Subclinical hypothyroidism and dyslipidemia in children and adolescents with type 1 diabetes mellitus

OBJECTIVE

Recent epidemiological evidence suggests that subclinical hypothyroidism (SCH), defined as elevated TSH concentrations with normal circulating levels of triiodothyronine (T3) and thyroxine (T4), is associated with dyslipidemia and cardiovascular disease in adult populations. As currently no data are available on the prevalence of SCH and its potential association with lipoprotein profile in children and adolescents with type 1 diabetes (T1DM), we investigated the prevalence of SCH and associated lipid levels in young diabetic patients.

DESIGN AND METHODS

Cross-sectional analysis of 22,747 children, adolescents, and young adults (age <25 years) with T1DM with normal T3 and T4 and either normal TSH (≥0.5 to <4.0 mIU/l, euthyroid group) or elevated TSH (≥4.0 to <25.0 mIU/l, SCH group) and simultaneous measurement of serum lipid and lipoprotein status.

RESULTS

The prevalence rate of SCH in the study population was 7.2%. Adjusted for age, gender, diabetes duration, current insulin dose, HbA1c, and BMI z-score, patients with SCH had significantly higher levels of total cholesterol (178.7 vs 175.3 mg/dl, P<0.001) and LDL-cholesterol (97.0 vs 93.7 mg/dl, P<0.001) compared with euthyroid patients.

CONCLUSIONS

SCH is a common finding in children, adolescents, and young adults with T1DM. SCH is associated with increased levels of total cholesterol, and LDL-cholesterol adjusted for potential confounders. SCH-associated increases in lipid and lipoprotein levels may therefore add to an increased long-term cardiovascular risk in young patients with T1DM.

Study of Optimal Replacement of Thyroxine in the ElDerly (SORTED): protocol for a mixed methods feasibility study to assess the clinical utility of lower dose thyroxine in elderly hypothyroid patients: study protocol for a randomized controlled trial

BACKGROUND

The population of the UK is ageing. There is compelling evidence that thyroid stimulating hormone distribution levels increase with age. Currently, in UK clinical practice elderly hypothyroid patients are treated with levothyroxine to lower their thyroid stimulating hormone levels to a standard non-age-related range. Evidence suggests that mortality is negatively associated with thyroid stimulating hormone levels. We report the protocol of a feasibility study working towards a full-scale randomized controlled trial to test whether lower dose levothyroxine has beneficial cardiovascular outcomes in the oldest old.

METHODS/DESIGN

SORTED is a mixed methods study with three components: SORTED A: A feasibility study of a dual-center single-blinded randomized controlled trial of elderly hypothyroid patients currently treated with levothyroxine.

SETTING

Patients will be recruited from 20 general practices and two hospital trust endocrine units in Northumberland, Tyne and Wear.

PARTICIPANTS

Target recruitment of 50 elderly hypothyroid patients currently treated with levothyroxine, identified in both primary and secondary care settings.

INTERVENTION

Reduced dose of levothyroxine to achieve an elevated serum thyroid stimulating hormone (target range 4.1 to 8.0 mU/L) versus standard levothyroxine replacement (target range 0.4 to 4.0 mU/L).

RANDOMIZATION

Using random permuted blocks, in a ratio of 1:1, randomization will be carried out by Newcastle Clinical Trials Unit.

OUTCOMES

Study feasibility (recruitment and retention rates and medication compliance), acceptability of the trial design, assessment of mobility and falls risk, and change in cardiovascular risk factors.

SORTED B

Qualitative study using in-depth interviews to understand patients' willingness to take part in a randomized controlled trial and participants' experience of the intervention.

SORTED C

Retrospective cohort study of 400 treated hypothyroid patients aged 80 years or over registered in 2008 in primary care practices, studying their 4-year cardiovascular outcomes to inform the power of SORTED II.

DISCUSSION

This is a study to evaluate the feasibility of conducting a randomized controlled trial in elderly hypothyroid patients in general practice and hospital settings. The results will inform the design of the definitive SORTED II trial to evaluate the effects of lower dose thyroxine in elderly hypothyroid patients.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN16043724.

Thyroid hormones as predictors of short- and long-term mortality in very old hospitalized patients

BACKGROUND

Although extensively investigated, the prognostic role of thyroid hormone abnormalities in older participants remains uncertain. We investigated the relationship between thyroid hormones and mortality during hospitalization and in a prolonged follow-up in frail older patients.

METHODS

A nonconcurrent cohort study was conducted by enrolling 450 participants hospitalized for an acute disease, who were classified into four groups (euthyroidism, hypothyroidism, hyperthyroidism, and low triiodothyronine [T3] syndrome), according to clinical and laboratory data. Multidimensional geriatric assessment variables were considered in order to identify short- and long-term predictors of death.

RESULTS

Participants were very old (mean age: 84 years) and frail, as indicated by severely impaired functional status, extensive comorbidity, high prevalence of dementia, and hospital mortality (8%). Prevalence of any thyroid dysfunction was 40.7%; 32% of participants had low T3 syndrome, which was associated with an excess hospital mortality risk (odds ratio: 2.7, 95% confidence interval [CI]: 1.1-6.5; p = .025), adjusted for demographic, clinical, functional, and laboratory data. Conversely, long-term mortality was unrelated to low T3 syndrome. In euthyroid participants, increasing levels of free thyroxine (FT4) were associated with a slightly greater mortality (hazard ratio, CI: 2.12, 0.99-4.54; p = .053) in adjusted Cox regression models.

CONCLUSIONS

This observational study on a cohort of very old, frail hospitalized patients gives support to the independent prognostic short-term, but not long-term, role of low T3 syndrome. Moreover, in older euthyroid participants, increasing levels of FT4 are a weak marker of poorer long-term survival. Thyroid hormones may help monitor changes in general health status and predict short- and long-term clinical outcomes in very old, frail patients.

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.

A prospective study of thyroid function, bone loss, and fractures in older men: The MrOS study

Excess thyroid hormone is associated with increased bone loss and fracture risk in older women, but few data exist for men. We sought to determine if thyroid function is independently associated with bone loss and fracture risk in older men. Data were analyzed from the Osteoporotic Fractures in Men (MrOS) study, a cohort of community-dwelling U.S. men aged 65 years and older. Using a case-cohort design, fasting baseline serum archived at -80°C was assayed for thyroid-stimulating hormone (thyrotropin) (TSH) and free thyroxine (FT4) in 397 men with confirmed nonspine fracture, including 157 hip fractures, and 1420 randomly selected men without fracture. TSH and FT4 were analyzed as continuous variables and as thyroid function categories (subclinical hyperthyroid, euthyroid, and subclinical hypothyroid). Hip dual-energy X-ray absorptiometry (DXA) (Hologic QDR4500) was measured at baseline and after a mean follow-up of 4.6 years. Incident nonspine fractures were centrally adjudicated. Bone loss was evaluated with multivariate regression methods and fractures risk was evaluated using hazard models that accounted for the case-cohort sampling, adjusted for age, clinic-site, body mass index (BMI), race, physical activity, corticosteroid use, smoking, alcohol intake, and thyroid medication use. In fully adjusted analyses, TSH was not associated with risk of nonspine fracture (relative hazard [RH] 0.92 per SD decrease in TSH; 95% confidence interval [CI], 0.74-1.14), but was significantly associated with risk of hip fracture (RH 1.31; 95% CI, 1.01-1.71), which persisted among normal range TSH values (RH 1.21; 95% CI, 1.00-1.47). There was no association between TSH or FT4 and bone loss, and fracture risk did not differ significantly by thyroid function category. We conclude that although neither TSH nor FT4 are associated with bone loss, lower serum TSH may be associated with an increased risk of hip fractures in older men.

Selective thyroid hormone receptor modulators

Thyroid hormone (TH) is known to have many beneficial effects on vital organs, but its extrapolation to be used therapeutically has been restricted by the fact that it does have concurrent adverse effects. Recent finding of various thyroid hormone receptors (TR) isoforms and their differential pattern of tissue distribution has regained interest in possible use of TH analogues in therapeutics. These findings were followed by search of compounds with isoform-specific or tissue-specific action on TR. Studying the structure-activity relationship of TR led to the development of compounds like GC1 and KB141, which preferentially act on the β1 isoform of TR. More recently, eprotirome was developed and has been studied in humans. It has shown to be effective in dyslipidemia by the lipid-lowering action of TH in the liver and also in obesity. Another compound, 3,5-diiodothyropropionic acid (DITPA), binds to both α- and β-type TRs with relatively low affinity and has been shown to be effective in heart failure (HF). In postinfarction models of HF and in a pilot clinical study, DITPA increased cardiac performance without affecting the heart rate. TR antagonists like NH3 can be used in thyrotoxicosis and cardiac arrhythmias. However, further larger clinical trials on some of these promising compounds and development of newer compounds with increased selectivity is required to achieve higher precision of action and avoid adverse effects seen with TH.

Current loss-of-function mutations in the thyrotropin receptor gene: when to investigate, clinical effects, and treatment

Thyroid-stimulating hormone receptor (TSHR) loss-of-function (LOF) mutations lead to a wide spectrum of phenotypes, ranging from severe congenital hypothyroidism (CH) to mild euthyroid hyperthyrotropinemia. The degree of TSH resistance depends on the severity of the impairment of the receptor function caused by the mutation and on the number of mutated alleles In this review data about genotype-phenotype correlation and criteria for clinical work-up will be presented and discussed. Complete TSH resistance due to biallelic LOF TSHR mutations must be suspected in all patients with severe not syndromic CH and severe thyroid hypoplasia diagnosed at birth by neonatal screening. Partial forms of TSH resistance show a more heterogeneous hormonal and clinical pattern . In these cases TSH serum levels are above the upper limit of normal range for the age but with a very variable pattern, free thyroxine (T4) concentrations are within the normal range and thyroid size can be normal or hypoplastic at ultrasound scan. An early substitutive treatment with L-T4 must be mandatory in all patients with severe CH due to complete uncompensated TSH resistance diagnosed at birth by neonatal screening. The usefulness of substitutive treatment appears much more controversial inpatients with subclinical hypothyroidism due to partial TSH resistance in whom the increased TSH concentration should be able to compensate the mild functional impairment of the mutant receptor. Together with standard criteria we recommend also an accurate clinical work-up to select patients who are candidates for a LOF TSHR mutation.

New-onset atrial fibrillation is a predictor of subsequent hyperthyroidism: a nationwide cohort study

AIMS

To examine the long-term risk of hyperthyroidism in patients admitted to hospital with new-onset AF. Hyperthyroidism is a well-known risk factor for atrial fibrillation (AF), but it is unknown whether new-onset AF predicts later-occurring hyperthyroidism.

METHODS AND RESULTS

All patients admitted with new-onset AF in Denmark from 1997-2009, and their present and subsequent use of anti-thyroid medication was identified by individual-level linkage of nationwide registries. Patients with previous thyroid diagnosis or thyroid medication use were excluded. Development of hyperthyroidism was assessed as initiation of methimazole or propylthiouracil up to a 13-year period. Risk of hyperthyroidism was analysed by Poisson regression models adjusted for important confounders such as amiodarone treatment. Non-AF individuals from the general population served as reference. A total of 145,623 patients with new-onset AF were included (mean age 66.4 years [SD ±13.2] and 55.3% males) of whom 3% (4,620 events; 62.2% women) developed hyperthyroidism in the post-hospitalization period compared to 1% (48,609 events; 82% women) in the general population (n = 3,866,889). In both women and men we found a significantly increased risk of hyperthyroidism associated with new-onset AF compared to individuals in the general population. The highest risk was found in middle-aged men and was consistently increased throughout the 13-year period of observation. The results were confirmed in a substudy analysis of 527,352 patients who had thyroid screening done.

CONCLUSION

New-onset AF seems to be a predictor of hyperthyroidism. Increased focus on subsequent risk of hyperthyroidism in patients with new-onset AF is warranted.

Subclinical hypothyroidism in the elderly: to treat or not to treat?

Aging is associated with a host of alterations in thyroid gland structure and function. Some of these changes have favorable effects on longevity, whereas others are maladaptive and contribute to a decline in health and quality of life. An area of particular controversy is the diagnosis and management of subclinical hypothyroidism in the elderly. The clinical diagnosis of hypothyroidism in the elderly is difficult, because many signs and symptoms associated with hypothyroidism are commonly present in euthyroid elderly individuals. The biochemical profile of subclinical hypothyroidism includes normal serum levels of thyroid hormones with mildly elevated serum thyrotropin concentrations in the range of 4.5 to 10 mIU/L. In this article, the epidemiology of subclinical hypothyroidism in the elderly is reviewed, the potential advantages of mild hypothyroidism in people over the age of 75 years are discussed, and some guidelines for screening and management of this common thyroid dysfunction are suggested.

A meta-analysis of thyroid-related traits reveals novel loci and gender-specific differences in the regulation of thyroid function

Thyroid hormone is essential for normal metabolism and development, and overt abnormalities in thyroid function lead to common endocrine disorders affecting approximately 10% of individuals over their life span. In addition, even mild alterations in thyroid function are associated with weight changes, atrial fibrillation, osteoporosis, and psychiatric disorders. To identify novel variants underlying thyroid function, we performed a large meta-analysis of genome-wide association studies for serum levels of the highly heritable thyroid function markers TSH and FT4, in up to 26,420 and 17,520 euthyroid subjects, respectively. Here we report 26 independent associations, including several novel loci for TSH (PDE10A, VEGFA, IGFBP5, NFIA, SOX9, PRDM11, FGF7, INSR, ABO, MIR1179, NRG1, MBIP, ITPK1, SASH1, GLIS3) and FT4 (LHX3, FOXE1, AADAT, NETO1/FBXO15, LPCAT2/CAPNS2). Notably, only limited overlap was detected between TSH and FT4 associated signals, in spite of the feedback regulation of their circulating levels by the hypothalamic-pituitary-thyroid axis. Five of the reported loci (PDE8B, PDE10A, MAF/LOC440389, NETO1/FBXO15, and LPCAT2/CAPNS2) show strong gender-specific differences, which offer clues for the known sexual dimorphism in thyroid function and related pathologies. Importantly, the TSH-associated loci contribute not only to variation within the normal range, but also to TSH values outside the reference range, suggesting that they may be involved in thyroid dysfunction. Overall, our findings explain, respectively, 5.64% and 2.30% of total TSH and FT4 trait variance, and they improve the current knowledge of the regulation of hypothalamic-pituitary-thyroid axis function and the consequences of genetic variation for hypo- or hyperthyroidism.

Levels of thyroid hormones are tightly regulated by TSH produced in the pituitary, and even mild alterations in their concentrations are strong indicators of thyroid pathologies, which are very common worldwide. To identify common genetic variants associated with the highly heritable markers of thyroid function, TSH and FT4, we conducted a meta-analysis of genome-wide association studies in 26,420 and 17,520 individuals, respectively, of European ancestry with normal thyroid function. Our analysis identified 26 independent genetic variants regulating these traits, several of which are new, and confirmed previously detected polymorphisms affecting TSH (within the PDE8B gene and near CAPZB, MAF/LOC440389, and NR3C2) and FT4 (within DIO1) levels. Gender-specific differences in the genetic effects of several variants for TSH and FT4 levels were identified at several loci, which offer clues to understand the known sexual dimorphism in thyroid function and pathology. Of particular clinical interest, we show that TSH-associated loci contribute not only to normal variation, but also to TSH values outside reference range, suggesting that they may be involved in thyroid dysfunction. Overall, our findings add to the developing landscape of the regulation of thyroid homeostasis and the consequences of genetic variation for thyroid related diseases.

Persistent subclinical hypothyroidism and cardiovascular risk in the elderly: the cardiovascular health study

CONTEXT

Use of a single set of thyroid function tests to define subclinical hypothyroidism may lead to misclassification over time and could influence findings from longitudinal studies.

OBJECTIVE

We assessed the risks of coronary heart disease (CHD), heart failure (HF), and cardiovascular (CV) death in older adults with persistent subclinical hypothyroidism.

DESIGN, SETTING, AND PARTICIPANTS

The study included 679 subclinically hypothyroid and 4184 euthyroid U.S. individuals at least 65 yr old enrolled in the Cardiovascular Health Study and not taking thyroid preparations.

MAIN OUTCOME MEASURE

We measured the 10-yr risk of incident CHD, HF, and CV death from persistent subclinical hypothyroidism, overall and stratified by degree of TSH elevation (4.5-6.9, 7.0-9.9, and 10.0-19.9 mU/liter).

RESULTS

There was no association between persistent subclinical hypothyroidism and incident CHD [hazard ratio (HR), 1.12; 95% confidence interval (CI), 0.93-1.36], HF (HR, 1.05; 95% CI, 0.97-1.27), or CV death (HR, 1.07; 95% CI, 0.87-1.31) in adjusted analyses in which subclinical hypothyroidism was modeled as a time-varying exposure using up to four serial thyroid function tests. When subclinical hypothyroidism was stratified by degree of TSH elevation, no significant associations were found in any stratum. Findings were similar in fixed exposure analyses in which only participants with testing 2 yr apart were considered, with no association between persistent or transient subclinical hypothyroidism and incident CHD, HF, or CV death.

CONCLUSIONS

Our data do not support increased risk of CHD, HF, or CV death in older adults with persistent subclinical hypothyroidism.

Subclinical hypothyroidism, mood, and cognition in older adults: a review

OBJECTIVES

To perform a critical review of the literature on the mood and cognitive changes associated with subclinical hypothyroidism (SCH), with an emphasis on older adults. To evaluate these data against the Consensus Statement on the management of SCH from the American Association of Clinical Endocrinologists, the American Thyroid Association, and The Endocrine Society.

METHOD

A comprehensive literature review.

RESULTS

Subclinical hypothyroidism may be associated with an increased risk of mood and cognitive dysfunction, although the strength of this association and the efficacy of replacement hormone therapy require further investigation.

CONCLUSION

It remains unclear whether SCH leads to significant mood and cognitive impairments in most older patients. More research is required to determine the nature and extent of this association and whether thyroid hormone replacement therapy is appropriate and effective in treating SCH-associated neurobehavioral impairments.

Using body mass index to predict optimal thyroid dosing after thyroidectomy

BACKGROUND

Current postoperative thyroid replacement dosing is weight based, with adjustments made after thyroid-stimulating hormone values. This method can lead to considerable delays in achieving euthyroidism and often fails to accurately dose over- and underweight patients. Our aim was to develop an accurate dosing method that uses patient body mass index (BMI) data.

STUDY DESIGN

A retrospective review of a prospectively collected thyroid database was performed. We selected adult patients undergoing thyroidectomy, with benign pathology, who achieved euthyroidism on thyroid hormone supplementation. Body mass index and euthyroid dose were plotted and regression was used to fit curves to the data. Statistical analysis was performed using STATA 10.1 software (Stata Corp).

RESULTS

One hundred twenty-two patients met inclusion criteria. At initial follow-up, only 39 patients were euthyroid (32%). Fifty-three percent of patients with BMI >30 kg/m(2) were overdosed, and 46% of patients with BMI <25 kg/m(2) were underdosed. The line of best fit demonstrated an overall quadratic relationship between BMI and euthyroid dose. A linear relationship best described the data up to a BMI of 50. Beyond that, the line approached 1.1 μg/kg. A regression equation was derived for calculating initial levothyroxine dose (μg/kg/d = -0.018 × BMI + 2.13 [F statistic = 52.7, root mean square error of 0.24]).

CONCLUSIONS

The current standard of weight-based thyroid replacement fails to appropriately dose underweight and overweight patients. Body mass index can be used to more accurately dose thyroid hormone using a simple formula.

Endocrine disorders in childhood and adolescence. Natural history of subclinical hypothyroidism in children and adolescents and potential effects of replacement therapy: a review

OBJECTIVE

Subclinical hypothyroidism (SH) is quite common in children and adolescents. The natural history of this condition and the potential effects of replacement therapy need to be known to properly manage SH. The aim of this review is to analyze: i) the spontaneous evolution of SH, in terms of the rate of reversion to euthyroidism, the persistence of SH, or the progression to over hypothyroidism; and ii) the effects of replacement therapy, with respect to auxological data, thyroid volume, and neuropsychological functions.

METHODS

We systematically searched PubMed, Cochrane, and EMBASE (1990-2012) and identified 39 potentially relevant articles of which only 15 articles were suitable to be included.

RESULTS AND CONCLUSIONS

SH in children is a remitting process with a low risk of evolution toward overt hypothyroidism. Most of the subjects reverted to euthyroidism or remained SH, with a rate of evolution toward overt hypothyroidism ranging between 0 and 28.8%, being 50% in only one study (nine articles). The initial presence of goiter and elevated thyroglobulin antibodies, the presence of celiac disease, and a progressive increase in thyroperoxidase antibodies and TSH value predict a progression toward overt hypothyroidism. Replacement therapy is not justified in children with SH but with TSH 5-10 mIU/l, no goiter, and negative antithyroid antibodies. An increased growth velocity was observed in children treated with levothyroxine (l-T(4); two articles). l-T(4) reduced thyroid volume in 25-100% of children with SH and autoimmune thyroiditis (two studies). No effects on neuropsychological functions (one study) and posttreatment evolution of SH (one study) were reported.

Thyroid function and the risk of coronary heart disease: 12-year follow-up of the HUNT study in Norway

OBJECTIVE

In a mortality follow-up of the HUNT Study, serum TSH within the reference range was positively associated with the risk of coronary death in women. We now aimed to confirm the association of high serum TSH with the risk of coronary heart disease, using hospital-based diagnoses of myocardial infarction.

DESIGN

Prospective population-based study with linkage to hospital information on myocardial infarction and to the national Cause of Death Registry.

PARTICIPANTS

A total of 26, 707 people without previously known thyroid or cardiovascular disease or diabetes at baseline.

MEASUREMENTS

Hazard ratios (HR) of coronary death and HRs of hospitalization with a first-time acute myocardial infarction, by baseline thyroid function.

RESULTS

During 12, years of follow-up, 960 (3·6%) participants had been hospitalized with first-time myocardial infarction and 558 (2·1%) had died from coronary heart disease. High TSH within the reference range was associated with increased risk of coronary death in women (P(trend) 0·005), but not in men. The risk of coronary death was also increased among women with subclinical hypothyroidism or subclinical hyperthyroidism, compared to women with TSH of 0·50-1·4 mU/l. However, thyroid function was not associated with the risk of being hospitalized with myocardial infarction.

CONCLUSIONS

High serum TSH was associated with increased mortality from coronary heart disease in women, but we found no association of thyroid function with the risk of being hospitalized with myocardial infarction. Thus, the morbidity finding does not confirm the suggestion that low thyroid function within the clinically normal range is associated with increased risk of coronary heart disease.

Higher free thyroxine levels predict increased incidence of dementia in older men: the Health in Men Study

CONTEXT

Both hypothyroidism and subclinical hyperthyroidism hinder cognitive function.

OBJECTIVE

We aimed to determine whether more subtle alterations of thyroid hormone levels predict increased incidence of dementia in aging men.

PARTICIPANTS AND DESIGN

Community-dwelling men aged 70-89 yr participated in this prospective longitudinal study.

MAIN OUTCOME MEASURES

The Standardized Mini-Mental State Examination was performed at baseline (2001-2004), and circulating TSH and free T(4) (FT(4)) were assayed. Men with known thyroid disease or dementia, or Standardized Mini-Mental State Examination scores below 24 were excluded from follow-up. New-onset dementia, defined by International Classification of Disease (ICD) codes, was ascertained using data linkage (2001-2009).

RESULTS

During follow-up, 145 of 3401 men (4.3%) were diagnosed for the first time with dementia. Men who developed dementia had higher baseline FT(4) (16.5 ± 2.2 vs. 15.9 ± 2.2 pmol/liter, P = 0.004) but similar TSH (2.2 ± 1.4 vs. 2.3 ± 1.6 mU/liter, P = 0.23) compared with men who did not receive this diagnosis. After adjusting for covariates, higher FT(4) predicted new-onset dementia (11% increased risk per 1 pmol/liter increase in FT(4), P = 0.005; quartiles Q2-4 vs. Q1: adjusted hazard ratio = 1.76, 95% confidence interval = 1.03-3.00, P = 0.04). There was no association between TSH quartiles and incident dementia. When the analysis was restricted to euthyroid men (excluding those with subclinical hyper- or hypothyroidism), higher FT(4) remained associated with incident dementia (11% increase per unit increment, P = 0.03; Q2-4 vs. Q1: adjusted hazard ratio = 2.02, 95% confidence interval = 1.10-3.71, P = 0.024).

CONCLUSIONS

Higher FT(4) levels predict new-onset dementia in older men, independently of conventional risk factors for cognitive decline. Additional studies are needed to explore potential underlying mechanisms and to clarify the utility of thyroid function testing in older men at risk of dementia.

The thyroid gland and the process of aging; what is new?

The endocrine system and particular endocrine organs, including the thyroid, undergo important functional changes during aging. The prevalence of thyroid disorders increases with age and numerous morphological and physiological changes of the thyroid gland during the process of aging are well-known. It is to be stressed that the clinical course of thyroid diseases in the elderly differs essentially from that observed in younger individuals, because symptoms are more subtle and are often attributed to normal aging. Subclinical hypo- and hyperthyroidism, as well as thyroid neoplasms, require special attention in elderly subjects. Intriguingly, decreased thyroid function, as well as thyrotropin (TSH) levels - progressively shifting to higher values with age - may contribute to the increased lifespan.This short review focuses on recent findings concerning the alterations in thyroid function during aging, including these which may potentially lead to extended longevity, both in humans and animals.

Effects of subclinical hypothyroidism treatment on psychiatric symptoms, muscular complaints, and quality of life

OBJECTIVES

To evaluate the impact of subclinical hypothyroidism (sHT) treatment on health-related quality of life (QoL), psychiatric symptoms, clinical score, and muscle function.

MATERIALS AND METHODS

In this randomized double-blind study, patients were assigned either to treatment (n = 35) or placebo (n = 36). Clinical and psychiatric symptoms were assessed by the Zulewski, Hamilton and Beck scales. QoL was assessed by the SF-36 questionnaire. Assessments of quadriceps (QS) and inspiratory muscle (IS) strength were performed by a chair dynamometer and a manuvacuometer.

RESULTS

Treatment improved IS (+11.5 ± 17.2; p = 0.041), as did QoL domains "Pain" and "Role Physical" (+19.7 ± 15.2, 0.039 and +22.1 ± 47.5, p = 0.054; respectively). Clinical and psychiatric symptoms showed similar responses to both interventions.

CONCLUSIONS

sHT treatment improved IS and physical aspects of QoL, despite no impact in other muscle parameters. Clinical score, psychiatric symptoms, and SF-36 domains, based on mental dimensions of QoL may be more susceptible to "placebo effect" in patients with sHT.

Age and gender substantially influence the relationship between thyroid status and the lipoprotein profile: results from a large cross-sectional study

BACKGROUND

Conflicting data are reported on the association between mild thyroid failure and lipid profile, primarily regarding serum triglyceride values and patients with slightly elevated thyrotropin (TSH, <10 mIU/L). In this study, we assessed the possible influence of gender and age on this relationship.

METHODS

The study included 2308 consecutive patients who were seen for suspected or diagnosed thyroid disease (1874 women, 434 men, mean age 47.5±14.1 and 46.9±14.0 years, respectively) and on whom studies of thyroid status and lipoprotein profile were conducted after an overnight fast. Patients with uncontrolled diabetes mellitus and those taking lipid-lowering drugs were excluded.

RESULTS

There were 628 patients receiving L-thyroxine who had a diagnosis of hypothyroidism: 200 were hyperthyroid, and 120 were still hypothyroid. Overall, 648 patients were hypothyroid, and 290 were hyperthyroid. No gender difference in the frequency of TSH values in the ranges studied (i.e., TSH frequency distribution) was observed. Total cholesterol (TC) and low-density lipoprotein cholesterol (LDLc) values (p<0.0003 and p<0.003, respectively) as well as the LDL/high-density lipoprotein cholesterol (HDLc) ratio (p<0.03) were elevated not only in unselected women with TSH values in the 4th TSH group (>10 mIU/L) but also in those of the 3rd group (3.6-10.0 mIU/L) who were older than 50 years (TC and LDLc p=0.01, LDL/HDLc ratio p=0.02 vs. euthyroid women). Among unselected men, only those of the 4th TSH group had elevated triglyceride (p<0.0001) but not cholesterol values. However, men of the 3rd and 4th TSH group who were older than 65 years had significantly higher TC, LDLc, and LDL/HDLc values as well (p=0.03, p=0.02 and p=0.01, respectively vs. euthyroid men). In the final model of stepwise regression for predicting each lipid parameter variation on the basis of age, TSH, free thyroxine (FT4), and body mass index (BMI) analysis, age had the highest standardized coefficient (0.36 and 0.37, respectively), followed by TSH (0.20 and 0.11, respectively) and FT4 (-0.11 and -0.09, respectively) when looking at TC and LDLc; whereas BMI had the highest standardized coefficient (0.28), followed by age (0.15) and TSH (0.11) when looking at triglyceride variation.

CONCLUSIONS

This study confirms a gender differentiation in the relationship between hypothyroidism and the lipid profile, which is substantially influenced by age, especially in patients with mild thyroid impairment (TSH<10 mIU/L).

Mechanisms in endocrinology: Heart failure and thyroid dysfunction

CONTEXT

Heart failure (HF) is a major cause of morbidity and mortality in Europe and in the United States. The aim of this review article was to assess the results of the prospective studies that evaluated the risk of HF in patients with overt and subclinical thyroid disease and discuss the mechanism of this dysfunction.

EVIDENCE ACQUISITION

Reports published with the following search terms were searched:, thyroid, hypothyroidism, hyperthyroidism, subclinical hyperthyroidism, subclinical hypothyroidism, levothyroxine, triiodothyronine, antithyroid drugs, radioiodine, deiodinases, clinical symptoms, heart rate, HF, systolic function, diastolic function, systemic vascular resistance, endothelial function, amiodarone and atrial fibrillation. The investigation was restricted to reports published in English.

EVIDENCE SYNTHESIS

The outcome of this analysis suggests that patients with untreated overt thyroid dysfunction are at increased risk of HF. Moreover, persistent subclinical thyroid dysfunction is associated with the development of HF in patients with serum TSH <0.1 or > 10 mU/l.

CONCLUSIONS

The timely recognition and effective treatment of cardiac symptoms in patients with thyroid dysfunction is mandatory because the prognosis of HF may be improved with the appropriate treatment of thyroid dysfunction.

Subclinical hypothyroidism in young women with polycystic ovary syndrome: an analysis of clinical, hormonal, and metabolic parameters

OBJECTIVE

To analyze the relationship between selected clinical and metabolic parameters in young women with polycystic ovary syndrome (PCOS) and normal thyroid function or subclinical hypothyroidism (SCH).

DESIGN

A cross-sectional cohort study.

SETTING

Tertiary care clinic.

PATIENT(S)

Women diagnosed with PCOS according to the Rotterdam criteria (n = 168).

INTERVENTION(S)

Clinical, hormonal, and metabolic parameters were evaluated. SCH was defined as TSH levels of 4.5-10 mIU/L.

MAIN OUTCOME MEASURE(S)

Separately, PCOS and SCH exert adverse effects on metabolic parameters; however, in conjunction their effect is unclear. This study evaluated whether SCH in women with PCOS affects clinical, hormonal, and metabolic parameters.

RESULT(S)

The mean age of the 168 women was 24 ± 5.8 years. Mean body mass index was 33.4 ± 8.2 kg/m(2). Thyroid function was normal in 149 women, and 19 had SCH. Only serum low-density lipoprotein cholesterol and PRL levels were significantly higher in the women with SCH (122.6 ± 25.6 mg/dL and 17.7 ± 7.7 ng/mL, respectively) compared with those with normal thyroid function (105.6 ± 33 mg/dL and 14 ± 10.3 ng/mL, respectively).

CONCLUSION(S)

In young women with PCOS, SCH is associated with higher low-density lipoprotein cholesterol levels, albeit with no changes in other lipid profile parameters, insulin resistance, or phenotypic manifestations. This study adds to current evidence supporting an association between PCOS and SCH.

Clinical review: The thyroid in mind: cognitive function and low thyrotropin in older people

CONTEXT

Several studies have reported an association between low serum TSH, or subclinical hyperthyroidism (SH), and dementia, but little emphasis has been placed on this field because not all studies have demonstrated the same association. We performed a detailed systematic review to assess the evidence available to support the association between these two conditions.

METHODS

We performed a systematic search through the PubMed, Embase (1996 to 2012 wk 4), Cochrane Library, and Medline (1996 to January wk 4, 2012) electronic databases using key search terms encompassing subclinical hyperthyroidism, TSH, dementia, and cognitive impairment.

RESULTS

This review examines the 23 studies that provide information about the association between SH or lower serum TSH within the reference range and cognition. Fourteen of these studies, including several well-designed and well-powered cross-sectional and longitudinal analyses, have shown a consistent finding of an association between SH with cognitive impairment or dementia.

CONCLUSION

There is a substantial body of evidence to support the association between SH and cognitive impairment, but there is no clear mechanistic explanation for these associations. Nor is there an indication that antithyroid treatment might ameliorate dementia. Larger and more detailed prospective longitudinal or randomized controlled trials are required to inform these important questions.

PROXIMAL FEMORAL EPIPHYSIOLYSIS AND SUBCLINICAL HYPOTHYROIDISM: CASE REPORT

Proximal femoral epiphysiolysis is an orthopedic disease that is prevalent during adolescence, because this coincides with the time of greatest growth of osteomuscular structures. Curiously, some patients present this disease early, and this outcome converts to the possible etiological explanation that the slippage might occur through a growth spurt. For these patients, the genesis of the slippage has not yet been elucidated, but endocrine disorders have been noted as possible causes. In an attempt to strengthen the theory of endocrinological etiology and present the results from surgical treatment for this pathological condition, the case of a male patient aged 9 years and 3 months with proximal femoral epiphysiolysis and subclinical hypothyroidism who was diagnosed and treated at our university's teaching hospital is reported here.

TSH-suppressive doses of levothyroxine are required to achieve preoperative native serum triiodothyronine levels in patients who have undergone total thyroidectomy

OBJECTIVE

Thyroidal production of triiodothyronine (T(3)) is absent in patients who have undergone total thyroidectomy. Therefore, relative T(3) deficiency may occur during postoperative levothyroxine (L-T(4)) therapy. The objective of this study was to evaluate how the individual serum T(3) level changes between preoperative native thyroid function and postoperative L-T(4) therapy.

METHODS

We retrospectively studied 135 consecutive patients with papillary thyroid carcinoma, who underwent total thyroidectomy. Serum free T(4) (FT(4)), free T(3) (FT(3)), and TSH levels measured preoperatively were compared with those levels measured on postoperative L-T(4) therapy.

RESULTS

serum tsh levels during postoperative L-T(4) therapy were significantly decreased compared with native TSH levels (P<0.001). serum FT(4) levels were significantly increased (P<0.001). Serum FT(3) levels were significantly decreased (P=0.029). We divided the patients into four groups according to postoperative serum TSH levels: strongly suppressed (less than one-tenth of the lower limit); moderately suppressed (between one-tenth of the lower limit and the lower limit); normal limit; and more than upper limit. Patients with strongly suppressed TSH levels had serum FT(3) levels significantly higher than the native levels (P<0.001). Patients with moderately suppressed TSH levels had serum FT(3) levels equivalent to the native levels (P=0.51), and patients with normal TSH levels had significantly lower serum FT(3) levels (P<0.001).

CONCLUSIONS

Serum FT(3) levels during postoperative L-T(4) therapy were equivalent to the preoperative levels in patients with moderately suppressed TSH levels. Our study indicated that a moderately TSH-suppressive dose of L-T(4) is required to achieve the preoperative native serum T(3) levels in postoperative L-T(4) therapy.

How could we improve the increased cardiovascular mortality in patients with overt and subclinical hyperthyroidism?

Over the past five years several meta-analyses have evaluated the cardiovascular mortality in patients with hyperthyroidism. They assessed various studies in which different inclusion criteria were used for the analysis of the cardiovascular mortality. More selective criteria have been used in recent meta-analyses. Only prospective cohort studies were included and only cohorts using second and third generation TSH assays were chosen. In addition, only the studies where the TSH evaluation was repeated during the follow-up were selected. The results of these recent meta-analyses provide evidence that overt and subclinical hyperthyroidism, particularly in patients with undetectable serum TSH, may increase the cardiovascular mortality. However, still today, the results remain inconclusive and not sufficient enough to recommend treatment for patients with low-detectable serum TSH. The high cardiovascular risk and mortality in presence of thyroid hormone excess suggest that this dysfunction is an important health problem and requires guidelines for the treatment of patients at high cardiovascular risk. Rigorous studies are necessary to evaluate the effects of the various causes of hyperthyroidism on the clinical outcomes. Randomized controlled clinical trials are needed to assess the benefits of treatment to improve the cardiovascular mortality and morbidity of mild and overt hyperthyroidism.

Natural history, diagnosis and management of subclinical thyroid dysfunction

Subclinical thyroid dysfunction (STD) represents a condition of slight thyroid hormone excess or deficiency, which may be associated with important adverse effects. This review will focus on the natural history, diagnosis and management of subclinical thyroid dysfunction. Since STD is only detected as a thyroid stimulating hormone (TSH) abnormality, it is essential to exclude transient causes of abnormal serum TSH before treating this disorder. Treatment of subclinical hyperthyroidism (SHyper) is recommended in elderly patients with undetectable serum TSH for the increased risk of atrial fibrillation, osteoporosis and bone fractures and for the higher risk of progression to overt disease. Treatment of subclinical hypothyroidism should be considered in patients with serum TSH above 10 mU/L for the increased risk of progression to overt hypothyroidism and the increased risk of coronary heart disease and heart failure events, which have been documented in patients with TSH increase above 10 mU/L. About 75% of patients with STD have mild dysfunction. The mild form of STD (low but detectable serum TSH in SHyper and mild increased serum TSH between 5 and 9 mU/L in SHypo is associated with a minor risk of disease progression to overt dysfunction. The best treatment for STD remains controversial. Treatment of the mild form of STD should be considered after evaluating the patients' age, the adverse risk factors, the potential beneficial effects of treating this disorder and any underlying co-morbidities. Mild SHypo should be treated in infertile and pregnant women.

Preservation of renal function by thyroid hormone replacement therapy in chronic kidney disease patients with subclinical hypothyroidism

CONTEXT

Subclinical hypothyroidism is not a rare condition, but the use of thyroid hormone to treat subclinical hypothyroidism is an issue of debate.

OBJECTIVE

This study was undertaken to investigate the impact of thyroid hormone therapy on the changes in estimated glomerular filtration rate (eGFR) in subclinical hypothyroidism patients with stage 2-4 chronic kidney disease.

PATIENTS

A total of 309 patients were included in the final analysis.

MAIN OUTCOME MEASURE

The changes in eGFR over time were compared between patients with and without thyroid hormone replacement therapy using a linear mixed model. Kaplan-Meier curves were constructed to determine the effect of thyroid hormone on renal outcome, a reduction of eGFR by 50%, or end-stage renal disease. The independent prognostic value of subclinical hypothyroidism treatment for renal outcome was ascertained by multivariate Cox regression analysis.

RESULTS

Among the 309 patients, 180 (58.3%) took thyroid hormone (treatment group), whereas 129 (41.7%) did not (nontreatment group). During the mean follow-up duration of 34.8 ± 24.3 months, the overall rate of decline in eGFR was significantly greater in the nontreatment group compared to the treatment group (-5.93 ± 1.65 vs. -2.11 ± 1.12 ml/min/yr/1.73 m(2); P = 0.04). Moreover, a linear mixed model revealed that there was a significant difference in the rates of eGFR decline over time between the two groups (P < 0.01). Kaplan-Meier analysis also showed that renal event-free survival was significantly lower in the nontreatment group (P < 0.01). In multivariate Cox regression analysis, thyroid hormone replacement therapy was found to be an independent predictor of renal outcome (hazard ratio, 0.28; 95% CI, 0.12-0.68; P = 0.01).

CONCLUSION

Thyroid hormone therapy not only preserved renal function better, but was also an independent predictor of renal outcome in chronic kidney disease patients with subclinical hypothyroidism.

Subclinical male hypogonadism

Male hypogonadism is traditionally defined as the inadequate production of testosterone and impaired spermatozoa generation in the presence of elevated or reduced levels of gonadotropins. A more frequent measurement of testosterone levels and the development of highly sensitive and specific assays have led to the detection of less clinically evident gonadal dysfunction, in which small biochemical alterations may or may not be accompanied by signs and symptoms. This condition is called "compensated" or "subclinical" hypogonadism. To determine whether subclinical hypogonadism is a paraphysiological state, a clinical condition in itself, or a precursor to overt hypogonadism, we carried out a literature review with the aim of establishing a practical approach to subclinical hypogonadism.

Subclinical hypopituitarism

The presence of subclinical or minor pituitary hormone deficiencies could be recognised in clinical practice and might represent intermediate situations among normal pituitary hormone secretion and clinical hypopituitarism. However, this entity has not been correctly identified and associated clinical impairment and even more, long-term consequences regarding to morbidity and mortality, strongly related to clinical hypopituitarism, has not been correctly settled. Furthermore, best test or methods for diagnosis and the cut off to define these intermediate situates are also unknown. With this purpose, long-term controlled studies are needed to define correctly this entity, the appropriate methods for diagnosis and the potential benefits of substitutive hormone therapy in detected cases. The present review will focus on the available evidence concerning the prevalence, clinical features and diagnosis of subclinical hypopituitarism.

Euthyroid goiter with and without nodules--diagnosis and treatment

BACKGROUND

Thyroid enlargement and thyroid nodules are common in the general population. This review concerns their proper diagnostic assessment and treatment.

METHODS

We selectively reviewed the literature from 1990 to 2012 and evaluated original articles and reviews retrieved from the PubMed database, as well as the recommendations of the following specialty societies: the German Societies of Endocrinology and Nuclear Medicine (Deutsche Gesellschaft für Endokrinologie, Deutsche Gesellschaft für Nuklearmedizin), the German Working Group for Endocrine Surgery (Chirurgische Arbeitsgemeinschaft Endokrinologie, CAEK), the European Thyroid Association, and the American Thyroid Association.

RESULTS

There have been very few randomized trials concerning the diagnosis and treatment of goiter. Nodular goiter can be managed by watchful waiting, drug treatment (initially with levothyroxine and iodide), radioactive iodine therapy, or surgery.

CONCLUSION

Many patients with nodules need no treatment at all. Treatment is indicated, however, if the patient is symptomatic and/or has an autonomously functioning ("hot") nodule, or if cancer is suspected. Potentially cancerous nodules must be operated on. If euthyroid nodular goiter is to be treated with the main goal of size reduction, either surgery or radioactive iodine therapy can be used. Drug treatment is an option for small nodules or goiters, but iatrogenic hyperthyroidism must be avoided at all costs. The type of follow-up that is required depends on the chosen treatment.

Subclinical thyroid dysfunction and the risk of heart failure events: an individual participant data analysis from 6 prospective cohorts

BACKGROUND

American College of Cardiology/American Heart Association guidelines for the diagnosis and management of heart failure recommend investigating exacerbating conditions such as thyroid dysfunction, but without specifying the impact of different thyroid-stimulation hormone (TSH) levels. Limited prospective data exist on the association between subclinical thyroid dysfunction and heart failure events.

METHODS AND RESULTS

We performed a pooled analysis of individual participant data using all available prospective cohorts with thyroid function tests and subsequent follow-up of heart failure events. Individual data on 25 390 participants with 216 248 person-years of follow-up were supplied from 6 prospective cohorts in the United States and Europe. Euthyroidism was defined as TSH of 0.45 to 4.49 mIU/L, subclinical hypothyroidism as TSH of 4.5 to 19.9 mIU/L, and subclinical hyperthyroidism as TSH <0.45 mIU/L, the last two with normal free thyroxine levels. Among 25 390 participants, 2068 (8.1%) had subclinical hypothyroidism and 648 (2.6%) had subclinical hyperthyroidism. In age- and sex-adjusted analyses, risks of heart failure events were increased with both higher and lower TSH levels (P for quadratic pattern <0.01); the hazard ratio was 1.01 (95% confidence interval, 0.81-1.26) for TSH of 4.5 to 6.9 mIU/L, 1.65 (95% confidence interval, 0.84-3.23) for TSH of 7.0 to 9.9 mIU/L, 1.86 (95% confidence interval, 1.27-2.72) for TSH of 10.0 to 19.9 mIU/L (P for trend <0.01) and 1.31 (95% confidence interval, 0.88-1.95) for TSH of 0.10 to 0.44 mIU/L and 1.94 (95% confidence interval, 1.01-3.72) for TSH <0.10 mIU/L (P for trend=0.047). Risks remained similar after adjustment for cardiovascular risk factors.

CONCLUSION

Risks of heart failure events were increased with both higher and lower TSH levels, particularly for TSH ≥10 and <0.10 mIU/L.

Combination treatment with T4 and T3: toward personalized replacement therapy in hypothyroidism?

CONTEXT

Levothyroxine therapy is the traditional lifelong replacement therapy for hypothyroid patients. Over the last several years, new evidence has led clinicians to evaluate the option of combined T(3) and T(4) treatment to improve the quality of life, cognition, and peripheral parameters of thyroid hormone action in hypothyroidism. The aim of this review is to assess the physiological basis and the results of current studies on this topic.

EVIDENCE ACQUISITION

We searched Medline for reports published with the following search terms: hypothyroidism, levothyroxine, triiodothyronine, thyroid, guidelines, treatment, deiodinases, clinical symptoms, quality of life, cognition, mood, depression, body weight, heart rate, cholesterol, bone markers, SHBG, and patient preference for combined therapy. The search was restricted to reports published in English since 1970, but some reports published before 1970 were also incorporated. We supplemented the search with records from personal files and references of relevant articles and textbooks. Parameters analyzed included the rationale for combination treatment, the type of patients to be selected, the optimal T(4)/T(3) ratio, and the potential benefits of this therapy on symptoms of hypothyroidism, quality of life, mood, cognition, and peripheral parameters of thyroid hormone action.

EVIDENCE SYNTHESIS

The outcome of our analysis suggests that it may be time to consider a personalized regimen of thyroid hormone replacement therapy in hypothyroid patients.

CONCLUSIONS

Further prospective randomized controlled studies are needed to clarify this important issue. Innovative formulations of the thyroid hormones will be required to mimic a more perfect thyroid hormone replacement therapy than is currently available.

Are hsCRP Levels and LDL/HDL Ratio Better and Early Markers to Unmask Onset of Dyslipidemia and Inflammation in Asymptomatic Subclinical Hypothyroidism?

The implications of subclinical hypothyroidism (SCH) are many amongst which the most important is progression to overt hypothyroidism. Other debatable aspects are its association with cardiovascular risk, neuromuscular and psychiatric dysfunction, increased predisposition to developing metabolic syndrome and an underlying pro-inflammatory state. We aimed to study the lipid profile, lipoprotein(a) [Lp(a)] and hsCRP levels and insulin resistance in a group of patients with SCH in a referral hospital and see if any significant differences exist between them and euthyroids. This is a case-control study where the selection of controls and cases was based on the thyroid profile. Subjects were selected on their visit to clinical biochemistry lab for thyroid function tests. 33 euthyroids were taken as controls (Group I) and 38 patients comprising of subclinical hypothyroids were grouped as cases (Group II). Serum thyroid stimulating hormone (TSH) was in the range of 0.5-5.0 mIU/L for euthyroids and for subclinical hypothyroids the concentration of TSH was more than 5 mIU/L. The concentration of tri-iodothyronine (T3) and thyroxine (T4) were in normal reference range in both the groups. Individual lipid profile parameters failed to show a significant p value between cases and controls. The LDL/HDL ratio was highly significant (p value < 0.0001) and hsCRP was also statistically between the two groups (p value = 0.0054). Lp(a) and insulin resistance did not differ significantly. SCH is a common disorder that frequently progresses to overt hypothyroidism. This study underlines the importance of LDL/HDL ratio rather than measurement of individual lipid profile parameters in bringing to light the dyslipidemic state associated with SCH. Moreover the use of hsCRP to detect an underlying pro-inflammatory state in SCH can also be emphasized.

Non-alcoholic fatty liver disease across the spectrum of hypothyroidism

BACKGROUND & AIMS

The aim of this study was to characterize the relationship between the broad spectrum of hypothyroidism and NAFLD.

METHODS

A cross-sectional study with 4648 health check-up subjects (2324 cases with hypothyroidism vs. age- and sex-matched controls) was conducted. The subjects were categorized as having either subclinical [thyroid-stimulating hormone (TSH) ≥4.1 mIU/L and normal free thyroixine (T(4)) level (0.7-1.8 ng/dl)] or overt hypothyroidism [free T(4)<0.7 ng/dl]. NAFLD was diagnosed on the basis of typical ultrasonographic findings, and alcohol consumption of less than 20 g/day in the absence of other causes of liver disease.

RESULTS

The mean age of the subjects was 48.6±11.8 years and 62.4% were female. NAFLD was significantly associated with hypothyroidism (30.2% patients vs. 19.5% control, p<0.001). The prevalence of NAFLD and abnormal liver enzyme levels (ALT>33/25 IU/L) increased steadily with increasing grades of hypothyroidism (for NAFLD, subclinical: 29.9% and overt: 36.3%; for abnormal ALT, 20.1% and 25.9%, p<0.001, respectively). Multivariate regression analysis showed that NAFLD was statistically significantly associated with hypothyroidism (odds ratio (OR) 1.38, 95% confidence interval (CI), 1.17-1.62) and the grade of hypothyroidism in a dose-dependent manner (OR 1.36, 95% CI, 1.16-1.61 in subclinical hypothyroidism and OR 1.71, 95% CI, 1.10-2.66 in overt hypothyroidism).

CONCLUSIONS

Subclinical hypothyroidism, even in the range of upper normal TSH levels, was found to be related to NAFLD in a dose-dependent manner. Hypothyroidism is closely associated with NAFLD independently of known metabolic risk factors, confirming a relevant clinical relationship between these two diseases.