Prevalencia de hipotiroidismo subclínico y biomarcadores de riesgo cardiovascular en pacientes del Hospital General de Riobamba / Prevalence of subclinical hypothyroidism and biomarkers of cardiovascular risk in patients of the General Hospital of Riobamba

El Hipotiroidismo subclínico (HSC) es definido bioquímicamente por una elevación en la concentración sérica de la hormona TSH con niveles normales de T4 libre. El objetivo de este estudio fue determinar la prevalencia de HSC en los pacientes que asistieron a la consulta de medicina interna del Hospital General IESS de Riobamba. Así como, analizar la correlación entre los parámetros hormonales y ciertos marcadores bioquímicos asociados con el incremento de riesgo cardiovascular. Se realizó una investigación de tipo descriptiva, observacional, con un diseño no experimental de corte transversal, que abarcó el periodo comprendido desde enero de 2019 hasta septiembre de 2021. 245 pacientes fueron diagnosticados con HSC, lo cual representó el 10.58 % del universo poblacional estudiado, 61.2% eran del sexo femenino, mientras que el 38.8% del sexo masculino. El mayor número de casos (59.61 %) se observó en el grupo etario mayor de 65 años, distribuidos de la siguiente manera: (22.86% hombres y 36.75% mujeres), también se encontró que el HSC está asociado con un perfil lipídico aterogénico, caracterizado por un incremento en la concentración de colesterol total y LDL los cuales se correlacionaron positivamente con las concentraciones de TSH.

Subclinical hypothyroidism (SH) is biochemically defined by an elevation in the serum concentration of TSH hormone with normal levels of free T4. The aim of this study was to determine the prevalence of SH in patients attending the internal medicine clinic of the General Hospital IESS of Riobamba. Also, to analyze the correlation between hormonal parameters and certain biochemical markers associated with increased cardiovascular risk. A descriptive, observational, non-experimental cross-sectional design was performed, covering the period from January 2019 to September 2021. 245 patients were diagnosed with SH, which represented 10.58 % of the population universe studied, 61.2% were female, while 38.8% were male. The highest number of cases (59.61 %) was observed in the age group over 65 years, distributed as follows: (22.86% men and 36.75% women), it was also found that SH is associated with an atherogenic lipid profile, characterized by an increase in the concentration of total cholesterol and LDL which correlated positively with TSH concentrations.

¿El tratamiento del hipotiroidismo subclínico tiene efecto sobre la morbimortalidad cardiovascular? / Does treatment of subclinical hypothyroidism have an effect on cardiovascular morbidity and mortality?

Un estudio mostró que el aumento de valores de la hormona estimulante de la tiroides se asoció a un aumento de mortalidad por todas las causas, estimando que las enfermedades cardiovasculares mediaban dicha asociación en aproximada-mente el 14 % de los casos. Asimismo se observó que el reemplazo con levotiroxina disminuiría los niveles de colesterol, lo cual podría tener un efecto en la reducción de enfermedades cardiovasculares. Partiendo de una viñeta clínica la autora intenta, a través de una búsqueda bibliográfica y análisis de la evidencia, determinar si el tratamiento del hipotiroidismo subclínico en adultos mayores reduciría la morbimortalidad por eventos cardiovasculares. (AU)

A study showed that increased thyroid-stimulating hormone levels were associated with increased all-cause mortality, with cardiovascular disease estimated to mediate this association in approximately 14 % of cases. Additionally, levothyroxine replacement was found to lower cholesterol levels, which could have an effect in reducing cardiovascular diseases. Basedon a clinical vignette, the author attempts, through a literature search and an analysis of the evidence, to determine whether treatment of subclinical hypothyroidism in older adults would reduce morbidity and mortality from cardiovascular events. (AU)

Incremento de la proteína C reactiva ultrasensible en pacientes con hipotiroidismo subclínico y su posible relación con el desarrollo de daño cardiovascular / Increase in high sensitivity C-reactive protein in patients with subclinical hypothyroidism and its possible relationship to the development of cardiovascular damages

INTRODUCCIÓN: El hipotiroidismo subclínico (HSC) se define bioquímicamente por una elevación en la concentración sérica de la hormona estimulante de la tiroides (TSH), con niveles normales de tiroxina libre (T4L). La asociación entre el HSC y el daño cardiovascular ha sido un tema controversial. OBJETIVO: determinar la asociación entre el HSC y el desarrollo de la enfermedad cardiovascular mediante la cuantificación de la proteína C reactiva ultrasensible PCR-us y la determinación de lípidos circulantes asociados a la enfermedad cardiovascular y la ateroesclerosis. MÉTODOS: Estudio descriptivo, correlacional de corte transversal realizado en el Hospital IESS de Riobamba, Ecuador en el periodo comprendido desde enero a diciembre de 2019. Se estudiaron 70 individuos (40 pacientes con HSC y 30 controles) con edades entre 18 y 75 años. Se realizaron las historias clínicas y el examen físico a cada paciente y la toma de las muestras sanguíneas para determinar la concentración sérica de los siguientes parámetros bioquímicos y hormonales: colesterol total, triglicéridos, HDL colesterol y LDL colesterol, TSH, T4L y PCR-us. RESULTADOS: Se encontró un incremento significativo en la concentración de colesterol total (p<0.0001), LDL colesterol (p<0.01) y PCR-us (p<0.0001) en los pacientes con HSC vs los controles. Se observó una correlación positiva (p<0.0001; r=0.9148) entre la TSH y la PCR-us en los pacientes con HSC. CONCLUSIÓN: los pacientes con HSC experimentan una elevación en los niveles séricos de PCR-us la cual está correlacionada con un incremento en la concentración sérica de TSH. Estos parámetros asociados a un aumento del colesterol total y de la LDL colesterol sugieren un estado inflamatorio de bajo grado que podría estar asociado con el desarrollo de aterosclerosis y daño cardiovascular.

INTRODUCTION: Subclinical hypothyroidism (SH) is defined biochemically by an elevation in serum thyroid stimulating hormone (TSH) concentration, with normal levels of free thyroxine (T4L). The association between SH and cardiovascular damage has been a controversial issue. OBJECTIVE: to determine the association between SH and the development of cardiovascular disease through the quantification of the high sensitivity C-reactive protein (hs-PCR) and the determination of circulating lipids associated to cardiovascular disease and atherosclerosis. METHODS: Observational, correlational cross-sectional study with patients captured in the internal medicine office as well as those attending screening activities at the IESS Hospital in Riobamba- Ecuador, in the period from January to December 2019. Seventy individuals (40 patients with SH and 30 controls) between the ages of 18 and 75 years were studied. Each patient's medical history and physical examination were performed, and blood samples were taken to determine the serum concentration of the following biochemical and hormonal parameters: total cholesterol, triglycerides, HDL cholesterol and LDL cholesterol, TSH, T4L and hs-PCR. RESULTS: A significant increase in the concentration of total cholesterol (p<0.0001), LDL cholesterol (p<0.01) and hs-PCR (p<0.0001) was found in patients with SH vs. controls. A positive correlation (p<0.0001; r=0.9148) was observed between TSH and hs-PCR in patients with SH. CONCLUSION: patients with SH experience an elevation in serum hs-PCR levels which is correlated with an increase in serum TSH concentration. These parameters associated with an increase in total cholesterol and LDL cholesterol suggest a low-grade inflammatory state that may be associated with the development of atherosclerosis and cardiovascular damage.

Reproductive outcomes in cases of subclinical hypothyroidism and thyroid autoimmunity: a narrative review / Resultados reprodutivos nos casos de hipotireoidismo subclínico e autoimunidade tireoidiana: Uma revisão narrativa

Abstract Thyroid diseases are relatively common in women in the reproductive period. It is currently understood that clinically-evident thyroid disorders may impair ovulation and, consequently, fertility. However, to date it has not been proven that high serum levels of thyroid-stimulating hormone and/or positivity for antithyroid antibodies are associated to a reduction in fertility, mainly in the absence of altered thyroxine levels. The present comprehensive review aims to present current data on the association between subclinical hypothyroidism and/or thyroid autoimmunity and reproductive outcomes.

Resumo As doenças da tireoide são relativamente comuns em mulheres no período reprodutivo. Atualmente, entende-se que distúrbios da tireoide clinicamente evidentes podem prejudicar a ovulação e, consequentemente, a fertilidade. No entanto, não se provou até o presente que níveis séricos altos do hormônio estimulador da tireoide e/ou positividade para anticorpos antitireoidianos estão associados a uma redução na fertilidade, sobretudo na ausência de níveis alterados de tiroxina. Esta revisão narrativa tem como objetivo apresentar dados atuais sobre a associação entre hipotireoidismo subclínico e/ou autoimunidade tireoidiana e resultados reprodutivos.

Macro TSH como causa de hipotiroidismo refractario: a propósito de dos casos clínicos / Macro TSH as a cause of refractory hypothyroidism: based on two clinical cases

Se presenta el caso de dos mujeres con hipotiroidismo, con TSH persistentemente elevada, lo que hacía aumentar la dosis de levotiroxina y llegar a un hipertiroidismo clínico con TSH anormalmente alto. Se realizó un seguimiento de los niveles de TSH y T4 libre, durante un período de 20 y 10 meses respectivamente. En ambas situaciones no hubo una respuesta esperable a las dosis de levotiroxina ascendentes. Después de descartar causas posibles que explicaran esta situación, se sospechó y confirmó la presencia de Macro TSH, que es un complejo biológicamente inactivo de TSH e Inmunoglobulina G. Se obtiene como resultado la estabilidad de ambas pacientes siendo su seguimiento prioritariamente clínico y con mediciones de T4L, comprendiendo por qué la TSH persiste elevada. Nos pareció interesante la comunicación de estos casos, que permite recordar causas atípicas de refractariedad al tratamiento con levotiroxina, como es la macro TSH, indispensable pesquisar para el manejo adecuado de estos pacientes.

An inadequate response to levothyroxine treatment in a patient with hypothyroidism suggests lack of intake, lack of absorption, nephrotic syndrome, thyroid hormone resistance among other reasons. We present the case of two women with hypothyroidism and a persistently elevated level of TSH, which required increasing the dose of levothyroxine, resulting in a clinical hyperthyroidism with an abnormally high TSH. A TSH and free T4 follow up was performed during a period of 20 and 10 months respectively, in both situations there was not an adequate response to rising levothyroxine treatment. After ruling out other possible causes that could explain this situation, it was suspected and then confirmed the presence of Macro TSH, which is a biologically inactive complex of TSH and Immunoglobulin G. Therefore, both patients achieved disease stability once controlled by clinical state and free T4 measurements, understanding why THS persited high. We present these interesting cases, because this allows us to remember atypical causes of refractory treatment with levothyroxine, such as the Macro TSH, indispensable to search for the proper management of these patients.

Serum irisin and apelin levels and markers of atherosclerosis in patients with subclinical hypothyroidism

ABSTRACT Objective: In this study, we aimed to evaluate serum irisin and apelin levels in patients with subclinical hypothyroidism (SCH) when they were subclinical hypothyroid and become euthyroid after levothyroxine therapy and association of these adipokines with markers of atherosclerosis such as serum homocysteine levels and carotid intima-media thickness (IMT). Subjects and methods: The study included 160 patients with newly diagnosed subclinical hypothyroidism due to Hashimoto's thyroiditis and 86 euthyroid healty subjects. Serum glucose and lipid profile, insulin, HOMA, TSH, free T3, free T4, anti-thyroperoxidase and anti-thyroglobulin antibodies, homocysteine, apelin and irisin levels were measured in all study subjects. Thyroid and carotid ultrasound examinations were performed. The subclinical hypothyroid group was reevaluated after 12-weeks of levothyroxine therapy when they became euthyroid. Results: Clinical characteristics of the patient and control group were similar. Glucose, insulin and HOMA levels, lipid parameters and free T3 were similar between the two groups.. Serum homocystein was higher and apelin was lower in patients with SCH, but irisin levels were similar between the two groups. While thyroid volume was lower, carotid IMT was significantly greater in patients with SCH (pCarotidIMT:0,01). After 12-weeks of levothyroxine therapy, all the studied parameters remained unchanged except, serum freeT4, TSH, homocystein and apelin. While homocystein decreased (p: 0,001), apelin increased significantly (p = 0,049). In multivariate analysis, low apelin levels significantly contributed to carotid IMT (p = 0,041). Conclusions: Apelin-APJ system may play a role in vascular and cardiac dysfunction in patients with SCH and treatment of this condition may improve the risk of cardiovascular disease.

Is There Any Relationship between TSH Levels and Prognosis in Acute Coronary Syndrome? / Existe Alguma Relação entre Níveis de TSH e Prognóstico em Síndrome Coronariana Aguda?

Abstract Background: Some small studies have related higher levels of thyrotropin (TSH) to potentially worse prognosis in acute coronary syndromes. However, this relationship remains uncertain. Objective: To analyze the outcomes of patients with acute coronary syndromes in relation to the value of TSH at admission. Methods: Observational and retrospective study with 505 patients (446 in group I [TSH ≤ 4 mIU/L] and 59 in group II [TSH > 4 mIU/L]) with acute coronary syndromes between May 2010 and May 2014. We obtained data about comorbidities and the medications used at the hospital. The primary endpoint was in-hospital all-cause death. The secondary endpoint included combined events (death, non-fatal unstable angina or myocardial infarction, cardiogenic shock, bleeding and stroke). Comparisons between groups were made by one-way ANOVA and chi-square test. Multivariate analysis was determined by logistic regression. Analyses were considered significant when p < 0.05. Results: Significant differences between groups I and II were observed regarding the use of enoxaparin (75.2% vs. 57.63%, p = 0.02) and statins (84.08% vs. 71.19%, p < 0.0001), previous stroke (5.83% vs. 15.25%, p = 0.007), combined events (14.80% vs. 27.12%, OR = 3.05, p = 0.004), cardiogenic shock (4.77% vs. 6.05%, OR = 4.77, p = 0.02) and bleeding (12.09% vs. 15.25%, OR = 3.36, p = 0.012). Conclusions: In patients with acute coronary syndromes and TSH > 4 mIU/L at admission, worse prognosis was observed, with higher incidences of in-hospital combined events, cardiogenic shock and bleeding.

Resumo Fundamento: Estudos pequenos têm relacionado níveis mais elevados de hormônio tireoestimulante (TSH) a pior prognóstico em pacientes com síndrome coronariana aguda (SCA). Tal relação, no entanto, permanece incerta. Objetivo: Analisar os desfechos de pacientes com SCA, relacionando-os aos níveis de TSH medidos no setor de emergência. Métodos: Estudo retrospectivo observacional incluindo 505 pacientes com SCA (446 no grupo I: TSH ± 4 mUI/L; 59 no grupo II: TSH > 4 mUI/L) entre maio de 2010 e maio de 2014. Dados sobre comorbidades e medicamentos usados foram obtidos. O desfecho primário foi mortalidade intra-hospitalar por todas as causas. O desfecho secundário incluiu eventos combinados (morte, angina instável não fatal ou infarto do miocárdio, choque cardiogênico, sangramento e acidente vascular encefálico). A comparação entre grupos foi realizada através de ANOVA de uma via e teste do qui-quadrado. A análise multivariada foi realizada por regressão logística, adotando-se o nível de significância de p < 0,05. Resultados: Diferenças significativas foram observadas entre os grupos I e II relacionadas ao uso de enoxaparina (75,2% vs. 57,63%; p = 0,02) e estatinas (84,08% vs. 71,19%; p < 0,0001), acidente vascular encefálico prévio (5,83% vs. 15,25%; p = 0,007), eventos combinados (14,80% vs. 27,12%, OR = 3,05; p = 0,004), choque cardiogênico (4,77% vs. 6,05%, OR = 4,77; p = 0,02) e sangramento (12,09% vs. 15,25%, OR = 3,36; p = 0,012). Conclusão: Em pacientes com SCA e TSH > 4 mUI/L à admissão hospitalar, observou-se pior prognóstico associado à maior incidência de eventos combinados intra-hospitalares, choque cardiogênico e sangramentos.

Treatment of hypothyroidism with levothyroxine plus liothyronine: a randomized, double-blind, crossover study

ABSTRACT Objective To compare the effects of a unique fixed combination levothyroxine/liothyronine (LT4/LT3) therapy in patients with primary hypothyroidism. Subjects and methods This is a randomized, double-blind, crossover study. Adults with primary hypothyroidism (n = 32, age 42.6 ± 13.3, 30 females) on stable doses of LT4 for ≥ 6 months (125 or 150 μg/day) were randomized to continue LT4 treatment (G1) or to start LT4/LT3 therapy (75/15 μg/day; G2). After 8 weeks, participants switched treatments for 8 more weeks. Thyroid function, lipid profile, plasma glucose, body weight, electrocardiogram, vital signs, and quality of life (QoL) were evaluated at weeks 0, 8 and 16. Results Free T4 levels were significantly lower while on LT4/LT3 (G1: 1.07 ± 0.29 vs. 1.65 ± 0.46; G2: 0.97 ± 0.26 vs. 1.63 ± 0.43 ng/dL; P < 0.001). TSH and T3 levels were not affected by type of therapy. More patients on LT4/LT3 had T3 levels above the upper limit (15% vs. 3%). The combination therapy led to an increase in heart rate, with no significant changes in electrocardiogram or arterial blood pressure. Lipid profile, body weight and QoL remained unchanged. Conclusions The combination therapy yielded significantly lower free T4 levels, with no changes in TSH or T3 levels. More patients on LT4/T3 had elevated T3 levels, with no significant alterations in the evaluated outcomes. No clear clinical benefit of the studied formulation could be observed. Future trials need to evaluate different formulations and the impact of the combined therapy in select populations with genetic polymorphisms.

Subclinical Hypothyroidism and Intracytoplasmic Sperm Injection Outcomes / Hipotireoidismo subclínico e resultados de Injeção intracitoplasmática de espermatozoide

Abstract Purpose Whether preconception elevated concentrations of thyroid-stimulating hormone (TSH) compromises reproductive outcomes in patients undergoing assisted reproduction techniques (ARTs) remains unclear. This study therefore compared the reproductive outcomes in patients with TSH concentrations of < 2.5 mIU/L, 2.5-4.0 mIU/L, and 4.0-10.0mIU/L undergoing controlled ovarian stimulation (COS) for in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI). Methods This retrospective cohort study evaluated the medical records of all women with measured TSH concentrations who underwent IVF/ICSI between January 2011 and December 2012. The patients were divided into three groups: TSH < 2.5mIU/L (group 1); THS ≥2.5 and < 4.0 mIU/L (group 2); and THS ≥4 mIU/L and < 10.0 mIU/L (group 3). Patients who were administered levothyroxine for treating hypothyroidism were excluded from the analysis. The primary endpoints were clinical pregnancy,miscarriage, live birth and multiple pregnancy rates. Results During the study period, 787 women underwent IVF/ICSI. Sixty were excluded because their TSH concentrations were unavailable, and 77 were excluded due to their use of levothyroxine. The prevalence of patients presenting elevated concentrations of TSHwas of 5.07% (using a TSH threshold of 4.0 mIU/L) and of 29.99% (using a TSH threshold of 2.5 mIU/L). Patient characteristics, type of COS, and response to COS did not differ among the three groups, and there were no differences in clinical pregnancy (24.4% versus 25.9% versus 24.2%, p = 0.93); miscarriage (17.1% versus 14.3% versus 12.5%, p = 0.93); live birth (20.2% versus 22.2% versus 21.2%, p = 0.86); and multiple pregnancy rates (27.0% versus 21.4% versus 25.0%, p = 0.90) respectively. Conclusion Response to COS, live birth, and miscarriage rates were not altered in women with elevated concentrations of TSH undergoing IVF/ICSI, regardless of using a TSH threshold of 2.5mIU/L or 4.0mIU/L. These findings reinforce the uncertainties related to the impact of subclinical hypothyroidism on reproductive outcomes in women undergoing COS for ARTs.

Resumo Objetivos Se concentrações elevadas de hormônio estimulante da tireoide (TSH) antes do parto comprometem resultados reprodutivos em pacientes submetidas a técnicas de reprodução assistida (TRA) é incerto. Este estudo comparou resultados reprodutivos de pacientes com concentrações de TSH < 2,5 mIU/L; 2,5-4,0 mIU/L e 4,0-10,0 mIU/L submetidas a estimulação ovariana controlada (EOC) para fertilização in vitro (FIV)/injeção intracitoplasmática de espermatozoide (ICSI). Métodos Este estudo de coorte retrospectiva avaliou prontuários médicos de todas as pacientes que tinham registro de concentrações de TSH submetidas a FIV/ICSI entre janeiro de 2011 e dezembro de 2012. As pacientes foram divididas em três grupos: aquelas com TSH < 2,5 mIU/L (grupo 1); entre 2,5 e 4,0 mIU/L (grupo 2) e entre 4,0 mIU/L e 10,0 mIU/L (grupo 3). As pacientes que estavam em uso de levotiroxina para tratamento de hipotireoidismo foram excluídas da análise. Os desfechos primários foram taxas de gravidez clínica, de abortamento, de nascido vivo e de gravidez múltipla. Resultados Durante o período do estudo, 787 mulheres foramsubmetidas a FIV/ICSI. Sessenta foram excluídas por causa da indisponibilidade das concentrações de TSH, e 77 foram excluídas porque estavam usando levotiroxina. A prevalência de pacientes apresentando elevação das concentrações de TSH foi de 5,07% (usando um limite de TSH de 4,0 mIU/L) e 29,99% (usando um limite de TSH de 2,5 mIU/L). As características das pacientes, tipo de EOC e reposta à EOC não diferiram entre os três grupos, nem houve diferenças nas taxas de gravidez clínica (24,4% versus 25,9% versus 24,2%, p = 0,93); abortamento (17,1% versus 14,3% versus 12,5%, p = 0,93); nascido vivo (20,2% versus 22,2% versus 21,2%, p = 0,86); e taxas de gestação múltipla (27,0% versus 21,4% versus 25,0%, p = 0,90), respectivamente. Conclusão Resposta à EOC, taxa de nascido vivo e de abortamento não foram alteradas em mulheres submetidas a FIV/ICSI com concentrações elevadas de TSH independente de usar um limite de 2,5 ou 4,0 mIU/L. Estes achados reforçam as incertezas relacionadas ao impacto do hipotireoidismo subclínico nos resultados reprodutivos de mulheres submetidas a EOC para TRA.

Circulating levels of irisin is elevated in hypothyroidism, a case-control study

Objective Our objective in this study was to determine the relationship between irisin hormone, which has a similar effect with thyroid hormones on adipose tissue and the metabolism, and the thyroid functions and the obesity secondary to thyroid disease. Subjects and methods Seventy-four patients were included in the study, of the patients, 37 were newly diagnosed with Hashimoto’s thyroiditis related hypothyroidism but not started on a treatment yet, and the remaining 37 were healthy volunteers without a known disease. Serum thyroid stimulating hormone (TSH), free thyroxin (fT4), anti-thyroglobulin and anti-thyroid peroxidase were measured and thyroid ultrasonography was performed in both groups. Serum irisin levels were measured using the commercially available ELISA kit. The hypothyroidism group had higher levels of irisin compared to the control group (2.77 ng/mL vs. 2.15 ng/mL respectively; p = 0.017). Results The hypothyroidism group had higher median levels of irisin in the obese patients than those in the control group (3.10 ng/mL vs. 2.10 ng/mL respectively; p = 0.013). Irisin level was negatively correlated with age in the whole population and patients with hypothyroidism (r = -0.255, p = 0.028; r = -0.346, p = 0.036 respectively). Irisin level was positively correlated with TSH (r = 0.247, p = 0.034) but negatively correlated with the fT4 (r = -0.316, p = 0.006) in the whole population. Obesity, fT4 and irisin levels were identified to be independent predictors in the diagnosis of hypothyroidism in the multivariable logistic regression analysis. Conclusion To the best of our knowledge, this study is the first in literature to identify that obesity, irisin level and fT4 level are independent risk factors for hypothyroidism.

Management of gestational hypothyroidism: results of a Brazilian survey

Objectives Evaluate the management of hypothyroidism in fertile-aged and pregnant women and compare these practices to the recommendations of the Brazilian Society of Endocrinology and Metabolism (SBEM) and the Latin American Thyroid Society, published in 2013. Materials and methods In the first trimester of 2014, SBEM made available to all members an electronic questionnaire based on clinical scenarios in the management of gestational hypothyroidism. The responses of 406 physicians, most of them endocrinologists, were analyzed. Results Eighty-one per cent of the endocrinologists screen all their pregnant patients for thyroid dysfunction, mostly during the pregestational period or after the first prenatal visit. Following screening, 82% of the respondents initiate treatment when TSH levels are > 2.5 mIU/L while 67% monitor their pregnant patients even if TSH was normal on first trimester screening. For hypothyroid women who are planning pregnancy, 96% of the clinicians are aware of the importance of adjusting the levothyroxine (LT4) dose as soon as pregnancy is confirmed. However, opinions diverge with respect to adjusting the LT4 dose before or after reassessing thyroid function. The most widely used tests for monitoring pregnant women in use of LT4 are TSH and free T4 (62%) or TSH alone (21%). Unanimously, the treatment goal is to achieve the target TSH level for each trimester of gestation. Conclusion The recommendations of the consensus statements are incorporated into the respondents’ clinical practice. It is noteworthy that the great majority of the clinicians favor universal screening.

Effects of thyroid hormone replacement on glycated hemoglobin levels in non diabetic subjects with overt hypothyroidism

Objective Glycated hemoglobin (HbA1c) may not accurately reflect the level of glycemia in conditions of altered erythrocyte turnover. Hypothyroidism is one condition associated with sluggish erythropoesis. To assess changes in HbA1c, independent of changes in plasma glucose after initiation of thyroxine replacement in patients with overt hypothyroidism. Materials and methods In this prospective longitudinal study carried out in a tertiary care centre, adult non-diabetic patients with overt hypothyroidism recruited between March 2012 to August 2013 were rendered euthyroid on thyroxine. They underwent testing for hemoglobin, HbA1c, reticulocyte count, thyroxine, thyrotropin and a standard oral glucose tolerance test, both before and at 3 months after restoration to the euthyroid state. Main outcome assessed was the change in HbA1c independent of the change in glucose parameters. Results Thirty eight patients (35 female and 3 male) aged 37.8 ± 10.2 years with overt hypothyroidism (thyroxine 12.6 ± 13.4 ng/mL and thyrotropin -98.1 ± 63.7 µIU/mL respectively) were recruited. While HbA1c fell from 5.8 ± 0.7% to 5.6 ± 0.5% (p = 0.009) at 3 months following the correction of hypothyroidism, there were no changes in the fasting and the 2 hr post oral glucose tolerance test glucose (p = 0.67 and 0.56 respectively). The number of patients with dysglycemia diagnosed by HbA1c (i.e HbA1c≥ 5.7%) fell from 25 (65.78%) to 17 (44.7%) after treatment (p = 0.008). There were 7 (18.4%) patients with HbA1c ≥ 6.5% at baseline, but this fell to just 4 (10.5%) (p < 0.001) after 3 months of euthyroidism. Conclusion HbA1c is not a reliable diagnostic test for diabetes in the presence of hypothyroidism.

The thyroid hormone receptor β-selective agonist GC-1 does not affect tolerance to exercise in hypothyroid rats

Objective Investigate the effect of GC-1 on tolerance to exercise in rats with experimental hypothyroidism. Materials and methods Hypothyroidism was induced with methimazole sodium and perchlorate treatment. Six groups with eight animals were studied: control group (C), hypothyroid group without treatment (HYPO); hypothyroidism treated with physiological doses of tetraiodothyronine (T4) or 10 times higher (10×T4); hypothyroidism treated with equal molar doses of GC-1 (GC-1) or 10 times higher (10×GC-1). After eight weeks, each animal underwent an exercise tolerance test by measuring the time (seconds), in which the rats were swimming with a load attached to their tails without being submerging for more than 10 sec. After the test, the animals were killed, and blood samples were collected for biochemical analysis, and the heart and soleus muscle were removed for weighing and morphometric analysis of the cardiomyocyte. Results Hypothyroidism significantly reduced tolerance to exercise and, treatment with GC-1 1× or T4 in physiological doses recover tolerance test to normal parameters. However, high doses of T4 also decreased tolerance to physical exercise. Conversely, ten times higher doses of GC-1 did not impair tolerance to exercise. Interestingly, hypothyroidism, treated or not with T4 in a physiological range, GC-1 or even high doses of GC-1 (10X) did not change cardiomyocyte diameters and relative weight of the soleus muscle. In contrast, higher doses of T4 significantly increased cardiomyocyte diameter and induced atrophy of the soleus muscle. Conclusion Unlike T4, GC-1 in high doses did not modify tolerance to physical exercise in the rats with hypothyroidism. .

Association between increased serum thyrotropin concentration and the oldest old: what do we know? / Associação entre aumento da concentração de tirotropina e longevos: o que sabemos?

To assess studies that evaluate the relation between serum thyrotropin concentration, very old subjects, and their events. We searched the PubMed, SciELO, and LILACS databases for articles published between 2004 and 2012. Our search was restricted to studies involving humans aged 65 years or older, and written in English, Spanish, or Portuguese. Studies that evaluated the association between elevated serum thyrotropin concentration among elderly subjects with subclinical hypothyroidism were chosen since at least in part they included a subpopulation of individuals aged 80 years and above. Thirteen studies were selected. No significant increase in risk of cardiovascular events, coronary heart disease, or total mortality was observed. Elevated thyrotropin concentration was associated with longevity. More randomized controlled trials are required to better define the potential benefits of elevated thyrotropin concentration in this oldest old population, hormone replacement, and longevity.

Avaliar os artigos que consideram a relação entre a concentração da tirotropina sérica, indivíduos muito idosos e seus eventos. Foram selecionados artigos do PubMed, SciELO e LILACS publicados entre 2004 e 2012, que consideraram uma população ≥65 anos, escritos em inglês, espanhol ou português. Os estudos que avaliaram a associação entre níveis séricos elevados de tirotropina sérica e idosos com hipotireoidismo subclínico foram escolhidos, desde que incluíssem uma subpopulação com 80 anos ou mais. Treze estudos foram selecionados. Não houve associação significante entre maior risco de eventos cardiovasculares, doença coronariana ou mortalidade. A concentração elevada de tirotropina sérica foi associada à longevidade. Mais estudos randomizados controlados são necessários para o melhor entendimento do potencial benefício da elevação de concentração da tirotropina sérica nos longevos, reposição hormonal e longevidade.

Gestational Age-specific Cut-off Values Are Needed for Diagnosis of Subclinical Hypothyroidism in Early Pregnancy

During the first trimester of pregnancy, thyroid-stimulating hormone (TSH) >2.5 mIU/L has been suggested as the universal criterion for subclinical hypothyroidism. However, TSH levels change continuously during pregnancy, even in the first trimester. Therefore the use of a fixed cut-off value for TSH may result in a different diagnosis rate of subclinical hypothyroidism according to gestational age. The objective of this study was to obtain the normal reference range of TSH during the first trimester in Korean gravida and to determine the diagnosis rate of subclinical hypothyroidism using the fixed cut-off value (TSH >2.5 mIU/L). The study population consisted of pregnant women who were measured for TSH during the first trimester of pregnancy (n=492) and nonpregnant women (n=984). Median concentration of TSH in pregnant women was lower than in non-pregnant women. There was a continuous decrease of median TSH concentration during the first trimester of pregnancy (median TSH concentration: 1.82 mIU/L for 3+0 to 6+6 weeks; 1.53 mIU/L for 7+0 to 7+6 weeks; and 1.05 mIU/L for 8+0 to 13+6 weeks). Using the fixed cut-off value of TSH >2.5 mIU/L, the diagnosis rate of subclinical hypothyroidism decreased significantly according to the gestational age (GA) at TSH (25% in 3+0 to 6+6 weeks, 13% in 7+0 to 7+6 weeks, and 9% for 8+0 to 13+6 weeks, P<0.001), whereas the diagnosis rate was 5% in all GA with the use of a GA-specific cut-off value (P=0.995). Therefore, GA-specific criteria might be more appropriate for the diagnosis of subclinical hypothyroidism.

The value of red blood cell distribution width in subclinical hypothyroidism / O valor da amplitude de distribuição de eritrócitos no hipotireoidismo subclínico

Objective : Therefore, we evaluated the relationship between the subclinical hypothyroidism and red cell distribution width (RDW) levels in a healthy population. Subjects and methods : The medical records of 23,343 consecutive health subjects were reviewed. Subjects were classified into four thyroid stimulating hormone (TSH) groups to determine the correlation between TSH and other variables in detail (0.3 to < 2.5 mU/L, 2.5 to < 5 mU/L, 5 to < 7.5 mU/L, and ≥ 7.5 mU/L). Results : In the multivariate linear regression analysis, RDW was associated with TSH levels, and e-GFR was inversely associated with TSH levels, respectively (standardized beta coefficient = 0.102, -0.019; p < 0.001, p < 0.001). After adjusting for age and sex, in the four groups, TSH levels were significantly correlated with RDW, estimated glomerular filtration rate (e-GFR), and free thyroxine (fT4) levels in all groups. Furthermore in the 4 th group, RDW levels were more strongly associated with TSH levels than in the other groups (p = 0.006). Conclusions : RDW levels are correlated with euthyroid and subclinical thyroid status. Notably, RDW is more correlated with subclinical hypothyroidism than the euthyroid status. This study presents the relationship between the RDW levels and thyroid function using TSH level in a large healthy population. .

Objetivo : Avaliamos a relação entre o hipotireoidismo subclínico e os níveis de distribuição do tamanho dos eritrócitos (RWD) em uma população saudável. Pacientes e métodos : Foram revisadas as fichas médicas de 23.343 sujeitos saudáveis consecutivos. Os sujeitos foram classificados em quatro grupos de nível de hormônio tireoestimulante (TSH) para se determinar a correlação entre o TSH e outras variáveis, em detalhe (0,3 a < 2,5 mU/L; 2,5 a < 5 mU/L; 5 a < 7,5 mU/L; e ≥ 7,5 mU/L). Resultados : Na análise de regressão linear múltipla, a distribuição do tamanho dos eritrócitos (RWD) foi associada aos níveis de TSH, e a taxa estimada de filtração glomerular (e-GFR) foi inversamente associada aos níveis de TSH, respectivamente (coeficiente betapadronizado = 0,102; -0,019; p < 0,001; p < 0,001). Depois do ajuste para idade e sexo, nos quatro grupos, os níveis de TSH se correlacionaram significativamente com os níveis de RDW, e-GFR e tiroxina livre (fT4) em todos os grupos. Além disso, no quarto grupo, os níveis de RDW estiveram mais fortemente associados aos níveis de TSH do que nos outros grupos (p = 0,006). Conclusões : Os níveis de RDW estão correlacionados com o estado eutiroide e com o hipotireoidismo subclínico. Notavelmente, a RDW é mais correlacionada com o hipotireoidismo subclínico do que com o estado eutiroide. Este estudo apresenta uma relação entre os níveis de RDW e a função tiroidiana por meio da concentração de TSH em um grande número de indivíduos saudáveis. .

Elevada frecuencia de enfermedad tiroidea funcional en embarazadas chilenas sin antecedentes de patología tiroidea utilizando el estándar de TSH internacional / Frequency of subclinical thyroid problems among women during the first trimester of pregnancy

Background: Thyroid hormones play an important role in fetal neural and cognitive development. Therefore thyroid abnormalities should be detected and treated early during pregnancy. Aim: To assess the frequency and risk factors for functional thyroid disorders during the first trimester of pregnancy. Material and Methods: A blood sample was obtained from women during their first trimester of pregnancy, consulting in a prenatal care facility. Women with known thyroid diseases were excluded from the study. Thyroid stimulating hormone (TSH), total thyroxine (T4) and free thyroxine (fT4) were measured by electrochemoluminiscence. Antithyroid peroxidase antibodies (anti TPO) were measured by enzyme immunoassay. Results: Five hundred and ten women aged 25.7 ± 6.6 years were assessed. The frequency of clinical hypothyroidism was 0.6%, subclinical hypothyroidism 35.3% and clinical hyperthyroidism 1%. Five percent of women with hypothyroidism and 3.5% of euthyroid women had positive anti TPO antibodies. There was no association between the frequency of thyroid diseases and risk factors for thyroid diseases. Conclusions: There is a high frequency of subclinical thyroid diseases among women consulting in this prenatal care clinic.