Subclinical thyroid dysfunction and functional capacity among elderly

Background: Subclinical thyroid dysfunction is common among older people and has been associated with decreased functional capacity but with conflicting data. The aim of this study was to assess the association between subclinical thyroid dysfunction and functional capacity in an elderly population. Methods: We included 5182 participants with a mean age of 75.2 years from the Prospective Study of Pravastatin in the Elderly at Risk (PROSPER). Self-reported functional capacity was assessed using the Barthel Index (BI) and the Instrumental Activities of Daily Living (IADL) scores at baseline and during follow-up. Participants with subclinical hyperthyroidism (n=65) and subclinical hypothyroidism (n=173) were compared to euthyroid participants (n=4944). The association between persistent subclinical thyroid dysfunction and functional capacity and decline was also investigated. Results: At baseline, compared to euthyroid participants (BI 19.73±SE 0.06; IADL 13.52±0.02), there was no difference in functional capacity for participants with subclinical hyperthyroidism (BI 19.60±0.09; IADL 13.51±0.12, p>0.05) or subclinical hypothyroidism (BI 19.82±0.06; IADL 13.55±0.08, p>0.05). Over a mean 3.2-year follow-up period, there was no association between thyroid function and annual decline of either BI or IADL (p>0.05). No association was found between persistent subclinical thyroid dysfunction and functional capacity at baseline or during follow-up (p>0.05). Results were similar after excluding participants with a maximum BI and/or IADL score at baseline. Conclusion: Among well-functioning community-dwelling elderly, we found no evidence that subclinical thyroid dysfunction contributes to decreased functional capacity.

Subclinical thyroid dysfunction and cardiovascular outcomes among prospective cohort studies

The association between subclinical thyroid dysfunction and cardiovascular outcomes has been recently clarified with the publication of three individual participant data (IPD) analyses from the Thyroid Studies Collaboration. We identified original cohort studies with a systematic review and pooled individual data from over 70'000 participants to obtain a more precise estimate of the risks of cardiovascular outcomes associated with subclinical thyroid dysfunction. Subclinical hypothyroidism and subclinical hyperthyroidism, defined as normal thyroxine (FT4) levels with increased or decreased Thyroid-Stimulating Hormones (TSH or thyrotropin) respectively, are associated with increased risk of cardiovascular outcomes compared to euthyroid state, particularly in those with a more pronounced thyroid dysfunction. Specifically, subclinical hypothyroidism is associated with an increased risk of coronary heart disease (CHD) events, CHD mortality and heart failure (HF) events in individuals with higher TSH levels, particularly in those with TSH levels ≥10.0 mIU/L. Conversely, subclinical hyperthyroidism is associated with an increased risk of total mortality, CHD mortality, HF and atrial fibrillation, particularly in those with suppressed TSH levels <0.10 mIU/L. Pending ongoing randomized controlled trials, these observational findings allow identifying potential TSH thresholds for thyroid medication initiation based on risk of clinical outcomes, although clinical decision based solely on observational data need caution. The impact of thyroid replacement among the elderly with subclinical hypothyroidism is currently studied in a multicenter international randomized controlled trial (Thyroid Hormone Replacement for Subclinical Hypothyroidism Trial, TRUST trial).

Subclinical thyroid dysfunction and the risk for fractures: a systematic review and meta-analysis.

BACKGROUND Data on the association between subclinical thyroid dysfunction and fractures conflict. PURPOSE To assess the risk for hip and nonspine fractures associated with subclinical thyroid dysfunction among prospective cohorts. DATA SOURCES Search of MEDLINE and EMBASE (1946 to 16 March 2014) and reference lists of retrieved articles without language restriction. STUDY SELECTION Two physicians screened and identified prospective cohorts that measured thyroid function and followed participants to assess fracture outcomes. DATA EXTRACTION One reviewer extracted data using a standardized protocol, and another verified data. Both reviewers independently assessed methodological quality of the studies. DATA SYNTHESIS The 7 population-based cohorts of heterogeneous quality included 50,245 participants with 1966 hip and 3281 nonspine fractures. In random-effects models that included the 5 higher-quality studies, the pooled adjusted hazard ratios (HRs) of participants with subclinical hyperthyroidism versus euthyrodism were 1.38 (95% CI, 0.92 to 2.07) for hip fractures and 1.20 (CI, 0.83 to 1.72) for nonspine fractures without statistical heterogeneity (P = 0.82 and 0.52, respectively; I2= 0%). Pooled estimates for the 7 cohorts were 1.26 (CI, 0.96 to 1.65) for hip fractures and 1.16 (CI, 0.95 to 1.42) for nonspine fractures. When thyroxine recipients were excluded, the HRs for participants with subclinical hyperthyroidism were 2.16 (CI, 0.87 to 5.37) for hip fractures and 1.43 (CI, 0.73 to 2.78) for nonspine fractures. For participants with subclinical hypothyroidism, HRs from higher-quality studies were 1.12 (CI, 0.83 to 1.51) for hip fractures and 1.04 (CI, 0.76 to 1.42) for nonspine fractures (P for heterogeneity = 0.69 and 0.88, respectively; I2 = 0%). LIMITATIONS Selective reporting cannot be excluded. Adjustment for potential common confounders varied and was not adequately done across all studies. CONCLUSION Subclinical hyperthyroidism might be associated with an increased risk for hip and nonspine fractures, but additional large, high-quality studies are needed. PRIMARY FUNDING SOURCE Swiss National Science Foundation.

Subclinical thyroid dysfunction and the risk of stroke: a systematic review and meta-analysis

Subclinical thyroid dysfunction has been associated with coronary heart disease, but the risk of stroke is unclear. Our aim is to combine the evidence on the association between subclinical thyroid dysfunction and the risk of stroke in prospective cohort studies. We searched Medline (OvidSP), Embase, Web-of-Science, Pubmed Publisher, Cochrane and Google Scholar from inception to November 2013 using a cohort filter, but without language restriction or other limitations. Reference lists of articles were searched. Two independent reviewers screened articles according to pre-specified criteria and selected prospective cohort studies with baseline thyroid function measurements and assessment of stroke outcomes. Data were derived using a standardized data extraction form. Quality was assessed according to previously defined quality indicators by two independent reviewers. We pooled the outcomes using a random-effects model. Of 2,274 articles screened, six cohort studies, including 11,309 participants with 665 stroke events, met the criteria. Four of six studies provided information on subclinical hyperthyroidism including a total of 6,029 participants and five on subclinical hypothyroidism (n = 10,118). The pooled hazard ratio (HR) was 1.08 (95 % CI 0.87-1.34) for subclinical hypothyroidism (I (2) of 0 %) and 1.17 (95 % CI 0.54-2.56) for subclinical hyperthyroidism (I (2) of 67 %) compared to euthyroidism. Subgroup analyses yielded similar results. Our systematic review provides no evidence supporting an increased risk for stroke associated with subclinical thyroid dysfunction. However, the available literature is insufficient and larger datasets are needed to perform extended analyses. Also, there were insufficient events to exclude clinically significant risk from subclinical hyperthyroidism, and more data are required for subgroup analyses.

Subclinical thyroid dysfunction and fracture risk: a meta-analysis.

IMPORTANCE Associations between subclinical thyroid dysfunction and fractures are unclear and clinical trials are lacking. OBJECTIVE To assess the association of subclinical thyroid dysfunction with hip, nonspine, spine, or any fractures. DATA SOURCES AND STUDY SELECTION The databases of MEDLINE and EMBASE (inception to March 26, 2015) were searched without language restrictions for prospective cohort studies with thyroid function data and subsequent fractures. DATA EXTRACTION Individual participant data were obtained from 13 prospective cohorts in the United States, Europe, Australia, and Japan. Levels of thyroid function were defined as euthyroidism (thyroid-stimulating hormone [TSH], 0.45-4.49 mIU/L), subclinical hyperthyroidism (TSH <0.45 mIU/L), and subclinical hypothyroidism (TSH ≥4.50-19.99 mIU/L) with normal thyroxine concentrations. MAIN OUTCOME AND MEASURES The primary outcome was hip fracture. Any fractures, nonspine fractures, and clinical spine fractures were secondary outcomes. RESULTS Among 70,298 participants, 4092 (5.8%) had subclinical hypothyroidism and 2219 (3.2%) had subclinical hyperthyroidism. During 762,401 person-years of follow-up, hip fracture occurred in 2975 participants (4.6%; 12 studies), any fracture in 2528 participants (9.0%; 8 studies), nonspine fracture in 2018 participants (8.4%; 8 studies), and spine fracture in 296 participants (1.3%; 6 studies). In age- and sex-adjusted analyses, the hazard ratio (HR) for subclinical hyperthyroidism vs euthyroidism was 1.36 for hip fracture (95% CI, 1.13-1.64; 146 events in 2082 participants vs 2534 in 56,471); for any fracture, HR was 1.28 (95% CI, 1.06-1.53; 121 events in 888 participants vs 2203 in 25,901); for nonspine fracture, HR was 1.16 (95% CI, 0.95-1.41; 107 events in 946 participants vs 1745 in 21,722); and for spine fracture, HR was 1.51 (95% CI, 0.93-2.45; 17 events in 732 participants vs 255 in 20,328). Lower TSH was associated with higher fracture rates: for TSH of less than 0.10 mIU/L, HR was 1.61 for hip fracture (95% CI, 1.21-2.15; 47 events in 510 participants); for any fracture, HR was 1.98 (95% CI, 1.41-2.78; 44 events in 212 participants); for nonspine fracture, HR was 1.61 (95% CI, 0.96-2.71; 32 events in 185 participants); and for spine fracture, HR was 3.57 (95% CI, 1.88-6.78; 8 events in 162 participants). Risks were similar after adjustment for other fracture risk factors. Endogenous subclinical hyperthyroidism (excluding thyroid medication users) was associated with HRs of 1.52 (95% CI, 1.19-1.93) for hip fracture, 1.42 (95% CI, 1.16-1.74) for any fracture, and 1.74 (95% CI, 1.01-2.99) for spine fracture. No association was found between subclinical hypothyroidism and fracture risk. CONCLUSIONS AND RELEVANCE Subclinical hyperthyroidism was associated with an increased risk of hip and other fractures, particularly among those with TSH levels of less than 0.10 mIU/L and those with endogenous subclinical hyperthyroidism. Further study is needed to determine whether treating subclinical hyperthyroidism can prevent fractures.

Subclinical Thyroid Dysfunction and Depressive Symptoms among Elderly: A Prospective Cohort Study

BACKGROUND Subclinical hypothyroidism has been associated with depressive symptoms in cross-sectional studies, but prospective data and data on subclinical hyperthyroidism are scarce. METHODS In the Leiden sub-study of the Prospective Study of Pravastatin in the Elderly at Risk (PROSPER) among adults aged 70-82 years with pre-existing cardiovascular disease or known cardiovascular risk factors, TSH and free T4 levels were measured at baseline and repeated after 6 months to define persistent thyroid function status. Main outcome measures were depressive symptoms, assessed with the Geriatric Depression Scale 15 (GDS) at baseline and after 3 years. All analyses were adjusted for age, gender and education. RESULTS Among 606 participants (41% women, mean age 75 years) without anti-depressant medication, GDS scores at baseline did not differ for participants with subclinical hypothyroidism (n = 47; GDS 1.75, 95% CI 1.29-2.20, p = 0.50) or subclinical hyperthyroidism (n = 13; GDS 1.64 [0.78-2.51], p = 1.00) compared to euthyroid participants (n = 546, mean GDS 1.60 [1.46-1.73]). After 3 years, compared to euthyroid participants, change in GDS scores did not differ for participants with subclinical hypothyroidism (ΔGDS -0.03 [-0.50-0.44], p = 0.80), while subclinical hyperthyroidism was associated with an increase in GDS scores (ΔGDS 1.13 [0.32-1.93] p = 0.04). All results were similar for persistent subclinical thyroid dysfunction. CONCLUSIONS In this largest prospective study on the association of persistent subclinical thyroid dysfunction and depression, subclinical hypothyroidism was not associated with increased depressive symptoms among older adults at high cardiovascular risk. Persistent subclinical hyperthyroidism might be associated with increased depressive symptoms, which requires confirmation in a larger prospective study. © 2015 S. Karger AG, Basel.

Subclinical Thyroid Dysfunction and Frailty Among Older Men

CONTEXT Both subclinical thyroid dysfunction and frailty are common among older individuals, but data on the relationship between these 2 conditions are conflicting. OBJECTIVE The purpose of this study was to assess the cross-sectional and prospective associations between subclinical thyroid dysfunction and frailty and the 5 frailty subdomains (sarcopenia, weakness, slowness, exhaustion, and low activity). SETTING AND DESIGN The Osteoporotic Fractures in Men Study is a prospective cohort study. PARTICIPANTS Men older than 65 years (n = 1455) were classified into 3 groups of thyroid status: subclinical hyperthyroidism (n = 26, 1.8%), subclinical hypothyroidism (n = 102, 7.0%), and euthyroidism (n = 1327, 91.2%). MAIN OUTCOME MEASURES Frailty was defined using a slightly modified Cardiovascular Health Study Index: men with 3 or more criteria were considered frail, men with 1 to 2 criteria were considered intermediately frail, and men with no criteria were considered robust. We assessed the cross-sectional relationship between baseline thyroid function and the 3 categories of frailty status (robust/intermediate/frail) as well as the prospective association between baseline thyroid function and subsequent frailty status and mortality after a 5-year follow-up. RESULTS At baseline, compared with euthyroid participants, men with subclinical hyperthyroidism had an increased likelihood of greater frailty status (adjusted odds ratio, 2.48; 95% confidence interval, 1.15-5.34), particularly among men aged <74 years at baseline (odds ratio for frailty, 3.63; 95% confidence interval, 1.21-10.88). After 5 years of follow-up, baseline subclinical hypothyroidism and hyperthyroidism were not consistently associated with overall frailty status or frailty components. CONCLUSION Among community-dwelling older men, subclinical hyperthyroidism, but not subclinical hypothyroidism, is associated with increased odds of prevalent but not incident frailty.

Estudo de prevalência de disfunção tireoidiana em pacientes com diabetes mellitus acompanhados no ambulatório de diabetes do Hospital Universitário Pedro Ernesto

O diabetes mellitus(DM) e as disfunções tireoidianas(DT) são as duas desordens endocrinológicas mais comuns na prática clínica. A DT não reconhecida pode interferir no controle metabólico e adicionar mais risco a um cenário predisponente à doença cardiovascular. O objetivo deste estudo foi avaliar a prevalência da DT em pacientes com diabetes mellitus tipo 1 e tipo 2 (DM1 e DM2) e avaliar o risco cardiovascular em pacientes com DM2 com e sem DT utilizando parâmetros clínicos e laboratoriais. Trata-se de um estudo observacional de corte transversal. Foram avaliados 304 pacientes com DM2 e 82 pacientes com DM1. Os pacientes foram submetidos a um inquérito clínico-demográfico e avaliação laboratorial para determinação do perfil lipídico, glicídico e da função tireoidiana. Os pacientes com DM2 tiveram seus escores de risco cardiovascular em 10 anos determinados pelas equações de Framingham e do UKPDS risk engine. A frequência de disfunção tireoidiana entre os 386 pacientes foi de 14,7%, sendo de 13% nos que não possuíam disfunção prévia. A disfunção mais frequente encontrada foi de hipotireoidismo subclínico, com 13% no DM1 e de 12% no DM2. A prevalência de anticorpos anti-tireoperoxidase (TPO) positivos foi de 10,8%, sendo de14,6% em pacientes com DM1.Foram diagnosticados 44 (11,2%) novos casos de disfunção tireoidiana em pacientes que negavam ou desconheciam terem DT prévia.Destes novos casos, 12,8% em DM1 e 13,1% em DM2.Dos 49 pacientes com DT prévia, 50% dos DM1e 76% dos DM2 estavam compensados. Não foi observada diferença entre as médias do escore de risco de Framingham entre os pacientes DM2 com eutireoidismo e com hipotireoidismo subclínico. Observou-se uma associação entre o hipotireoidismo subclínico e risco cardiovascular nos pacientes com DM2 demonstrado pela diferença estatisticamente significativa entre as médias do escore UKPDS para doença coronariana não-fatal e fatal, acidente vascular cerebral fatal entre os dois grupos (p=0,007; 0,005;0,027 respectivamente). As demais funções tireodianas (hipotireoidismo clínico, hipertireoidismo clínico e subclínico) encontradas não foram analisadas devido ao pequeno número de pacientes em cada grupo.Concluímos que o rastreio da doença tireoidiana entre os pacientes com diabetes mellitus deve ser realizado rotineiramente considerando-se a prevalência de novos casos de DT diagnosticados e o fato de que os pacientes com DM2 e com hipotireoidismo subclínico avaliados possuírem um risco cardiovascular maior. Todavia, concluímos que estudos prospectivos e com maior número de pacientes são necessários para o esclarecimento do impacto da doença tireoidiana no risco cardiovascular do paciente com DM.

Thyroid function and prevalent and incident metabolic syndrome in older adults: the Health, Ageing and Body Composition Study.

OBJECTIVE: Both subclinical hypothyroidism and the metabolic syndrome have been associated with increased risk of coronary heart disease events. It is unknown whether the prevalence and incidence of metabolic syndrome is higher as TSH levels increase, or in individuals with subclinical hypothyroidism. We sought to determine the association between thyroid function and the prevalence and incidence of the metabolic syndrome in a cohort of older adults. DESIGN: Data were analysed from the Health, Ageing and Body Composition Study, a prospective cohort of 3075 community-dwelling US adults. PARTICIPANTS: Two thousand one hundred and nineteen participants with measured TSH and data on metabolic syndrome components were included in the analysis. MEASUREMENTS: TSH was measured by immunoassay. Metabolic syndrome was defined per revised ATP III criteria. RESULTS: At baseline, 684 participants met criteria for metabolic syndrome. At 6-year follow-up, incident metabolic syndrome developed in 239 individuals. In fully adjusted models, each unit increase in TSH was associated with a 3% increase in the odds of prevalent metabolic syndrome (OR, 1.03; 95% CI, 1.01-1.06; P = 0.02), and the association was stronger for TSH within the normal range (OR, 1.16; 95% CI, 1.03-1.30; P = 0.02). Subclinical hypothyroidism with a TSH > 10 mIU/l was significantly associated with increased odds of prevalent metabolic syndrome (OR, 2.3; 95% CI, 1.0-5.0; P = 0.04); the odds of incident MetS was similar (OR 2.2), but the confidence interval was wide (0.6-7.5). CONCLUSIONS: Higher TSH levels and subclinical hypothyroidism with a TSH > 10 mIU/l are associated with increased odds of prevalent but not incident metabolic syndrome.

Efectos cardiovasculares del hipotiroidismo clínico y subclínico en pacientes con síndrome coronario agudo

La disfunción tiroidea tiene un impacto ya demostrado en el sistema cardiovascular. No se ha establecido si existe alguna asociación entre el hipotiroidismo y la presencia de complicaciones cardiovasculares como falla cardiaca, angina postinfarto, arritmias y muerte, en el contexto de un síndrome coronario agudo. Objetivo: Determinar la asociación entre la disfunción tiroidea (hipotiroidismo clínico y subclínico) y la presencia de complicaciones cardiovasculares (falla cardiaca, arritmias, angina postinfarto y muerte) en pacientes con síndrome coronario agudo que ingresaron a la Unidad de Cuidado Coronario de la Fundación Cardioinfantil (UCC – FCI). Materiales y métodos: Estudio analítico de cohorte, donde se evaluó la cohorte expuesta (129 pacientes) y no expuesta (258 pacientes) que ingresaron a la UCC de la FCI, con diagnóstico de síndrome coronario agudo (Angina inestable, IAM SEST o IAM CEST) entre el periodo de enero de 2009 y marzo de 2010. Se evaluaron las asociaciones mediante el riesgo relativo e intervalo de confianza y la prueba de chi cuadrado. En el análisis multivariado se utilizó el modelo de regresión logística incondicional. Resultados: Se estudiaron en total 387 pacientes, 258 eutiroideos y 129 pacientes con disfunción tiroidea (hipotiroismo clínico e hipotiroidismo subclínico). La distribución según el sexo en la cohorte de expuestos y no expuestos fue de 67% vs 66.3% y de mujeres 31% vs 33.7%. El desenlace más frecuente en el grupo de pacientes expuestos fue falla cardiaca (13%). Se evidenció que los pacientes con hipotiroidismo clínico o subclínico tienen el doble de riesgo de presentar falla cardiaca (RR=2.2 IC 95%:1.1-4.3) y 3 veces más riesgo de presentar fibrilación auricular (RR=4 IC 95%:1.22–13.0). No hubo diferencias estadísticamente significativas en los demás desenlaces. El análisis multivariado mostró que el hipotiroidismo es un factor de riesgo suficiente para producir falla cardiaca y fibrilación auricular. Conclusiones: El hipotiroidismo clínico y subclínico aumentan el riesgo de desarrollar falla cardiaca y fibrilación auricular en pacientes con síndrome coronario agudo.

Efectos cardiovasculares del hipotiroidismo clínico y subclínico en pacientes con síndrome coronario agudo

Objetivo: determinar la asociación entre la disfunción tiroidea (hipotiroidismo clínico y subclínico) y la presencia de complicaciones cardiovasculares (falla cardiaca, arritmias, angina postinfarto y muerte) en pacientes con síndrome coronario agudo que ingresaron a la Unidad de Cuidado Coronario de un hospital de cuarto nivel en la ciudad de Bogotá, Colombia. Materiales y métodos: estudio analítico de cohorte prospectiva, donde se evaluó la cohorte expuesta (129 pacientes) y no expuesta (258 pacientes) que ingresaron a la UCC del hospital de cuarto nivel, con diagnóstico de síndrome coronario agudo: Angina inestable, IAM SEST (Infarto agudo del miocardio sin elevación del ST) o IAM CEST (Infarto agudo del miocardio con elevación del ST) entre el periodo de enero de 2009 y marzo de 2010. Se evaluaron las asociaciones mediante el riesgo relativo e intervalo de confianza y la prueba de chi cuadrado. En el análisis multivariado se utilizó el modelo de regresión logística incondicional. Resultados: Se estudiaron en total 387 pacientes, 258 eutiroideos y 129 pacientes con disfunción tiroidea (hipotiroidismo clínico e hipotiroidismo subclínico). La distribución según el sexo en la cohorte de expuestos y no expuestos fue de 67% vs 66.3% y de mujeres 31% vs 33.7%. El desenlace más frecuente en el grupo de pacientes expuestos fue falla cardiaca (13%). Se evidenció que los pacientes con hipotiroidismo clínico o subclínico tienen el doble de riesgo de presentar falla cardiaca (RR=2.2 IC 95%:1.1-4.3) y 3 veces más riesgo de presentar fibrilación auricular (RR=4 IC 95%:1.22–13.0). No hubo diferencias estadísticamente significativas en los demás desenlaces. El análisis multivariado mostró que el hipotiroidismo es un factor de riesgo suficiente para producir falla cardiaca y fibrilación auricular. Conclusiones: El hipotiroidismo clínico y subclínico aumentan el riesgo de desarrollar falla cardiaca y fibrilación auricular en pacientes con síndrome coronario agudo.

Desenlaces maternos y perinatales en pacientes con hipotiroidismo gestacional versus pre-gestacional en Bogotá 2009-2011.

Introducción: La segunda endocrinopatía que complica el embarazo es la enfermedad tiroidea, con una prevalencia de 2.5-5% en Estados Unidos. El hipotiroidismo en el embarazo se ha relacionado con efectos deletéreos maternos y perinatales, con evidencia escasa y controversial. Es importante conocer las diferencias en estos desenlaces en mujeres con hipotiroidismo pregestacional (HPG) y gestacional (HG). Metodología: Cohorte retrospectiva en una institución prestadora de salud (IPS) con HPG y HG, con registro de TSH en la historia clínica prenatal. Desenlaces maternos y perinatales: Amenaza de aborto, aborto espontáneo, hipertensión inducida por el embarazo, preeclamsia, abrupcio placenta, amenaza de parto pretérmino, óbito fetal, presentación podálica, cesárea, hemorragia posparto y bajo peso al nacer. Se compararon desenlaces entre pacientes con HPG versus HG y el tipo de hipotiroidismo (clínico, sub-clínico y controlado). Resultados: 337 gestantes entre Junio de 2009 y Diciembre de 2011, 67 con HPG. La TSH disminuyó del primero al tercer trimestre de embarazo en ambos grupos. El IMC en pacientes con HPG es mayor significativamente que en HG (p=0,04). Existe diferencia estadísticamente significativa entre tipo de hipotiroidismo clínico, subclínico y controlado en pacientes con HG y HPG en el primero y segundo trimestre (p<0.05). Con relación a desenlaces maternos y perinatales ninguno mostró asociación estadísticamente significativa, p>0.05. Conclusión: No se observaron diferencias significativas en los desenlaces materno-perinatales de pacientes con HG versus HPG, ambos grupos con suplencia hormonal tiroidea. Esto sugiere que independientemente del momento del diagnóstico, lo importante es tratar la enfermedad tempranamente para disminuir o evitar complicaciones.

Synergistic acceleration of thyroid hormone degradation by phenobarbital and the PPAR alpha agonist WY14643 in rat hepatocytes

Energy balance is maintained by controlling both energy intake and energy expenditure. Thyroid hormones play a crucial role in regulating energy expenditure. Their levels are adjusted by a tight feed back-control led regulation of thyroid hormone production/incretion and by their hepatic metabolism. Thyroid hormone degradation has previously been shown to be enhanced by treatment with phenobarbital or other antiepileptic drugs due to a CAR-dependent induction of phase 11 enzymes of xenobiotic metabolism. We have recently shown, that PPAR alpha agonists synergize with phenobarbital to induce another prototypical CAR target gene, CYP2B1. Therefore, it was tested whether a PPAR alpha agonist could enhance the phenobarbital-dependent acceleration of thyroid hormone elimination. In primary cultures of rat hepatocytes the apparent half-life of T3 was reduced after induction with a combination of phenobarbital and the PPARa agonist WY14643 to a larger extent than after induction with either Compound alone. The synergistic reduction of the half-life could be attributed to a synergistic induction of CAR and the CAR target genes that code for enzymes and transporters involved in the hepatic elimination of T3, such as OATP1A1, OATP1A3, UGT1A3 and UCT1A10. The PPAR alpha-dependent CAR induction and the subsequent induction of T3-eliminating enzymes might be of physiological significance for the fasting-incluced reduction in energy expenditure by fatty acids as natural PPARa ligands. The synergism of the PPAR alpha agonist WY14643 and phenobarbital in inducing thyroid hormone breakdown might serve as a paradigm for the synergistic disruption of endocrine control by other combinations of xenobiotics. (C) 2009 Elsevier Inc. All rights reserved.

Prevalência do hipotiroidismo subclínico e repercussões sobre o perfil lipídico e massa óssea em mulheres na pós-menopausa

OBJETIVO: avaliar a prevalência do hipotiroidismo subclínico e suas repercussões sobre o perfil lipídico e a densidade mineral óssea (DMO) em mulheres na pós-menopausa. Métodos: trata-se de estudo transversal com recuperação de dados de prontuários de pacientes acompanhadas em ambulatório de climatério. Critérios de inclusão: mulheres na pós-menopausa com dosagem do hormônio estimulador da tiróide (TSH) e de tiroxina livre (T4-L). Critérios de exclusão: hipertiroidismo e carcinoma de tiróide. Considerou-se hipotiroidismo subclínico valores de TSH superiores a 5,0 mUI/mL e T4-L normal. Foram selecionadas 320 pacientes (idade 55,2±6,4 anos) divididas em 3 grupos: função tiroideana normal (n=208), hipotiroidismo subclínico (n=53) e hipotiroidismo clínico sob tratamento (n=59). Foram analisados dados clínicos, uso de terapia hormonal, índice de massa corpórea (IMC=kg/m²), perfil lipídico (colesterol total, HDL, LDL, triglicerídeos) e DMO da coluna lombar e fêmur. Na análise estatística, as diferenças entre as médias dos grupos foram comparadas utilizando-se a análise de variância (ANOVA). Para múltipla comparação, assumindo que a variância era diferente entre os grupos, utilizou-se o método de Tukey. RESULTADOS: o hipotiroidismo subclínico foi diagnosticado em 16,1% dos casos. Os grupos foram homogêneos quanto às características clínicas, IMC e perfil lipídico e uso de terapêutica hormonal. Nas pacientes com hipotiroidismo subclínico ou clínico encontrou-se menor freqüência de osteopenia na coluna lombar e fêmur quando comparadas às eutiroidianas (p<0,001). Houve correlação negativa entre os valores de TSH e DMO da coluna lombar e fêmur (p<0,001). Não se constatou correlação entre os valores de TSH e idade, tempo de menopausa, IMC e perfil lipídico. O total de usuárias de terapia hormonal foi de 65,1%, duração média de 3,43±2,42 anos, não diferindo entre os grupos. CONCLUSÃO: o hipotiroidismo subclínico com prevalência de 16,1% na pós-menopausa associou-se à baixa DMO, mas sem repercussões sobre o perfil lipídico.

Profile of thyroid hormones in breast cancer patients

Estrogen involvement in breast cancer has been established; however, the association between breast cancer and thyroid diseases is controversial. Estrogen-like effects of thyroid hormone on breast cancer cell growth in culture have been reported. The objective of the present study was to determine the profile of thyroid hormones in breast cancer patients. Serum aliquots from 26 patients with breast cancer ranging in age from 30 to 85 years and age-matched normal controls (N = 22) were analyzed for free triiodothyronine (T3F), free thyroxine (T4F), thyroid-stimulating hormone (TSH), antiperoxidase antibody (TPO), and estradiol (E2). Estrogen receptor ß (ERß) was determined in tumor tissues by immunohistochemistry. Thyroid disease incidence was higher in patients than in controls (58 vs 18%, P < 0.05). Subclinical hyperthyroidism was the most frequent disorder in patients (31%); hypothyroidism (8%) and positive anti-TPO antibodies (19%) were also found. Subclinical hypothyroidism was the only dysfunction (18%) found in controls. Hyperthyroidism was associated with postmenopausal patients, as shown by significantly higher mean T3 and T4 values and lower TSH levels in this group of breast cancer patients than in controls. The majority of positive ERß tumors were clustered in the postmenopausal patients and all cases presenting subclinical hyperthyroidism in this subgroup concomitantly exhibited Erß-positive tumors. Subclinical hyperthyroidism was present in only one of 6 premenopausal patients. We show here that postmenopausal breast cancer patients have a significantly increased thyroid hormone/E2 ratio (P < 0.05), suggesting a possible tumor growth-promoting effect caused by this misbalance.