Tiroides Ectópica Lingual: caso Clínico / Lingual Ectopic Thyroid: a clinical case

La tiroides ectópica lingual es una patología muy poco frecuente, producida por la detención en el descenso normal de la glándula durante el desarrollo embrio-nario. La localización lingual de tejido tiroideo es la más común entre las tiroides ectópicas o aberrantes. Esta enfermedad puede ser asintomática pero, cuan-do los signos y síntomas están presentes, guardan estrecha correlación con la localización de la lesión y son proporcionales a su tamaño. El diagnóstico debe realizarse clínicamente y con el complemento de es-tudios por imágenes y endocrinológicos. En los aná-lisis de laboratorio se debe incluir dosaje de las hor-monas TSH, T4 libre y T3, vinculadas con la función tiroidea. Las biopsias deben evitarse ya que causan desequilibrio en la producción hormonal de la glándu-la y peligro de profusas hemorragias. En este artículo se desarrolla una descripción de las generalidades de la tiroides ectópica lingual, y se presenta un caso clínico de un niño con un tumor lingual, que fue deri-vado por su médica pediatra a cirugía para realizar una biopsia. Asimismo, se comenta la importancia que tiene para el odontólogo conocer esta patología a fin de poder evitar sus posibles complicaciones (AU)

Lingual thyroid is a rare disorder produced by a failure in the descent of thyroid gland to its normal position during embryological development. Lingual localization of thyroid tissue is the most common among the ectopic or aberrant thyroids. This condition can be asymptomatic, although when symptoms take place, they are connected to the lesion location and depend on its size. Diagnosis should be made clinically and complemented with imaging and endocrine studies. Laboratory analysis must include dosage of TSH, free T4 and T3, thyroid function-linked hormones. Due to the possible imbalance in the gland hormone production and the risk of massive bleeding, biopsy should be avoided. In this article, a brief description of lingual ectopic thyroid generalities is developed and a clinical case of a 7-years old child is provided. Additionally, dentistry importance of knowing this condition is commented, in order to prevent its possible complications (AU)

Síndrome nefrótico asociado a hipotiroidismo severo / Nephrotic syndrome associated to severe hypothyroidism

Las hormonas tiroideas tienen acciones renales directas en conjunto con efectos dinámicos y cardiovasculares que influyen en la función renal. Cuadros de hipotiroidismo con enfermedad renal son una combinación peculiar y poco descrita, es por ello que el propósito de este trabajo es exponer el caso de dos pacientes con síndrome nefrótico asociado a hipotiroidismo severo, los cuales presentaron disminución de la proteinuria y casi normalización de función renal luego de iniciar tratamiento de reemplazo con levotiroxina.

Thyroid hormones have direct renal actions in conjunction with dynamic and cardiovascular effects that influence renal function. Cases of primary hypothyroidism with renal disease are a peculiar and poorly described combination, is for it that the objective of this work is to expose the cases of two patients with nephrotic syndrome associated with severe hypothyroidism, whom presented decreased proteinuria and almost normalized renal function after starting replacement therapy with levothyroxine.

TSH-receptor antibodies may prevent bone loss in pre- and postmenopausal women with Graves' disease and Graves' orbitopathy

ABSTRACT Objective Thyrotoxicosis is established risk factor for osteoporosis due to increased bone turnover. Glucocorticoids often administered for Graves' orbitopathy (GO) have additional negative effect on bone mineral density (BMD). Our aim was to examine the influence of thyroid hormones, TSH, TSH-receptor antibodies (TRAb) and glucocorticoid treatment on bone in women with Graves' thyrotoxicosis and Graves' orbitopathy (GO). Subjects and methods Forty seven women with Graves' disease, mean age 55.6 ± 12.8 (23 women with thyrotoxicosis and 24 hyperthyroid with concomitant GO and glucocorticoid therapy) and 40 age-matched healthy female controls were enrolled in the study. We analyzed clinical features, TSH, FT4, FT3, TRAb, TPO antibodies. BMD of lumbar spine and hip was measured by DEXA and 10-year fracture risk was calculated with FRAX tool. Results The study showed significantly lower spine and femoral BMD (g/cm2) in patients with and without GO compared to controls, as well as significantly higher fracture risk. Comparison between hyperthyroid patients without and with orbitopathy found out significantly lower spine BMD in the first group (p = 0.0049). Negative correlations between FT3 and femoral neck BMD (p = 0.0001), between FT4 and BMD (p = 0.049) and positive between TSH and BMD (p = 0.0001), TRAb and BMD (p = 0.026) were observed. Fracture risk for major fractures and TRAb were negatively associated (p = 0.05). We found negative correlation of BMD to duration of thyrotoxicosis and cumulative steroid dose. Conclusions Our results confirm the negative effect of hyperthyroid status on BMD. TRAb, often in high titers in patients with GO, may have protective role for the bone, but further research is needed.

Rastreo de hipotiroidismo en pacientes embarazadas / Hypothyroidism screening in pregnancy

El embarazo es una situación clínica donde se produce un aumento fisiológico de la síntesis de hormona tiroidea y en la cual su carencia puede acarrear morbilidad perinatal. A partir de una viñeta clínica en la cual una médica solicita determinaciones de TSH y hormonas tiroideas a una mujer embarazada asintomática, la autora se plantea la utilidad del rastreo de hipotiroidismo en el embarazo. Luego de realizar una búsqueda bibliográfica y seleccionar la evidencia más reciente y de mejor calidad, se concluye que actualmente no existe sustento para rastrear hipotiroidismo en esta población. Por su parte, diferentes organizaciones recomiendan, a través de sus guías de práctica clínica, la búsqueda de casos teniendo en cuenta factores de riesgo específicos. (AU)

Pregnancy is a clinical condition where there is a physiological increase of thyroid hormone synthesis and in which its deficiency can lead to perinatal morbidity. From a clinical vignette in which a physician requests both TSH and thyroid hormone determinations to an asymptomatic pregnant woman, the author explores the usefulness hypothyroidism scree-ning in pregnancy. After carrying out a bibliographic search and selecting the most recent and best quality evidence, it is concluded that there is currently no firm evidence for sustaining hypothyroidism screening in this population. Although, different organizations recommend through its clinical practice guidelines hypothyroidism case finding in pregnancy taking into account specific risk factors. (AU)

Aspectos críticos do abuso de horm¶nios protéicos no exercício e no esporte: atualizaþÒo / [Critical aspects of peptide hormone abuse in exercise and sports: an update].

The hormonal abuse in physical exercise practioners is very common. Many pleople believe these substances can promote skeletal muscle hyperthrophy and improve physical fitness without health damaging effects. However, this is another myth that science unmasked. This article updates information regarding abuse of insulin, growth hormone, thyroid hormones, and erythropoitin. The peptide hormone abuse can cause motor paralysis, skeletal muscle damage and loss, diabetes mellitus, hypothyroidism, arterial hypertension, sweating, headaches, vomiting and enhances the risk for atherosclerosis, thrombosis, osteoporosis, and cancer.

Importance of iodine in pregnancy

Iodine is an essential constituent of thyroid hormones (TH). TH actively take part in critical periods of brain development during embryonic, fetal and postnatal stages. Therefore the absence of TH or iodine in these critical periods produces an irreversible brain damage. In fact, it is known that iodine deficiency is the leading cause of preventable brain damage worldwide. Because of the physiological adjustments during pregnancy iodine requirements increase significantly from 150 μg per day in non-pregnant adult women to 250 μg per day. Moreover, recent epidemiological studies around the world show that iodine intake during pregnancy is insufficient in many countries, even in developed countries like Australia, Spain and Italy. In the present work an overview of the importance of iodine nutrition during pregnancy is given.

Importancia del yodo en la gestación. El yodo es un nutrimento constituyente indispensable de las hormonas tiroideas (HT). Las HT participan activamente en periodos críticos del desarrollo cerebral durante las etapas embrionaria, fetal y posnatal. Por lo tanto la ausencia o deficiencia de las HT o de yodo en estas etapas del desarrollo produce un daño cerebral irreversible. De hecho, se sabe que la deficiencia de yodo es la principal causa de daño cerebral prevenible en el mundo. Debido a los ajustes fisiológicos propios de la gestación los requerimientos de yodo se incrementan notablemente, pasando de 150 μg al día en la mujer adulta no gestante a 250 μg al día durante el embarazo. Por otra parte, estudios epidemiológicos recientes hechos en todo el mundo muestran que el consumo de yodo durante la gestación es insuficiente en varios países; incluso en países desarrollados como Australia y España e Italia. En la presente revisión se da un panorama general de la importancia del consumo adecuado de yodo durante la gestación.

Levotiroxina e o problema da permutabilidade de drogas de estreito intervalo terapêutico / Levothyroxine and the problem of interchangeability of drugs with narrow therapeutic index

Tem se tornado prática comum em nosso país a troca de medicamentos prescritos por outros similares, por produtos genéricos e até mesmo por produtos manipulados, muitas vezes ignorando-se preceitos básicos de bioequivalência, permutabilidade, estabilidade e características específicas do composto farmacêutico. No caso de drogas de índice terapêutico estreito, como a levotiroxina, esses problemas se agravam colocando em sério risco a eficácia do tratamento e a saúde do paciente. Revemos a legislação pertinente ressaltando as características da levotiroxina e os efeitos adversos que limitam a permutabilidade do composto.

The exchange of a prescribed drug by other similar, by generic products and even by custom products has become common practice in our country, often ignoring basic tenets of bioequivalence, interchangeability, stability and characteristics of the pharmaceutical compounds. In the case of drugs of narrow therapeutic index, such as levothyroxine, these problems are intensified, putting the effectiveness of treatment and patient health at serious risk. We review the pertinent legislation, emphasizing the characteristics of levothyroxine and adverse effects that limit the interchangeability of the compound.

Effect of triiodothyronine on the maxilla and masseter muscles of the rat stomatognathic system

The maxilla and masseter muscles are components of the stomatognathic system involved in chewing, which is frequently affected by physical forces such as gravity, and by dental, orthodontic and orthopedic procedures. Thyroid hormones (TH) are known to regulate the expression of genes that control bone mass and the oxidative properties of muscles; however, little is known about the effects of TH on the stomatognathic system. This study investigated this issue by evaluating: i) osteoprotegerin (OPG) and osteopontine (OPN) mRNA expression in the maxilla and ii) myoglobin (Mb) mRNA and protein expression, as well as fiber composition of the masseter. Male Wistar rats (~250 g) were divided into thyroidectomized (Tx) and sham-operated (SO) groups (N = 24/group) treated with T3 or saline (0.9 percent) for 15 days. Thyroidectomy increased OPG (~40 percent) and OPN (~75 percent) mRNA expression, while T3 treatment reduced OPG (~40 percent) and OPN (~75 percent) in Tx, and both (~50 percent) in SO rats. Masseter Mb mRNA expression and fiber type composition remained unchanged, despite the induction of hypo- and hyperthyroidism. However, Mb content was decreased in Tx rats even after T3 treatment. Since OPG and OPN are key proteins involved in the osteoclastogenesis inhibition and bone mineralization, respectively, and that Mb functions as a muscle store of O2 allowing muscles to be more resistant to fatigue, the present data indicate that TH also interfere with maxilla remodeling and the oxidative properties of the masseter, influencing the function of the stomatognathic system, which may require attention during dental, orthodontic and orthopedic procedures in patients with thyroid diseases.

Hipotiroidismo, miocardiopatía dilatada y síndrome nefrótico durante el embarazo / Hypothyroidism, dilated cardiomyopathy and nephrotic syndrome during pregnancy

El hipotiroidismo en el embarazo es infrecuente, pero cuando ocurre suele asociarse con complicaciones maternas y fetales. Se presenta el caso de una mujer joven sin antecedentes de enfermedad cardiovascular que consulta por ortopnea, dolor torácico y edema de miembros inferiores. Los exámenes pusieron en evidencia la existencia de insuficiencia cardíaca, hipotiroidismo, síndrome nefrótico e insuficiencia renal. El eco-Doppler mostró dilatación de las cuatro cavidades cardíacas con deterioro grave de la función sistólica. El tratamiento con levotiroxina por vía intravenosa mejoró el cuadro clínico y los parámetros de laboratorio. Se analizan los efectos de la hormona tiroidea sobre el aparato cardiovascular y se comentan los mecanismos fisiopatológicos de la insuficiencia cardíaca en el embarazo.

Hypothyroidism during pregnancy is infrequent, but its presence is associated with maternal and fetal complications. We present the case of a young pregnant woman with no previous history of cardiovascular disease, who consulted for orthopnea, chest pain and edema in both legs. Laboratory tests demonstrated a hypothyroid condition and a nephrotic syndrome with renal failure. The echo-Doppler exam showed a four chamber dilatation with systolic dysfunction. Treatment with intravenous levothyroxine improved her medical condition. We analyze the effects of thyroid hormone on the heart and vascular system and discuss the pathophysiologic mechanisms of heart failure during pregnancy.

Imbalance between thyroid hormones and the dopaminergic system might be central to the pathophysiology of restless legs syndrome: a hypothesis

Data collected from medical literature indicate that dopaminergic agonists alleviate Restless Legs Syndrome symptoms while dopaminergic agonists antagonists aggravate them. Dopaminergic agonists is a physiological regulator of thyroid-stimulating hormone. Dopaminergic agonists infusion diminishes the levels of thyroid hormones, which have the ability to provoke restlessness, hyperkinetic states, tremors, and insomnia. Conditions associated with higher levels of thyroid hormones, such as pregnancy or hyperthyroidism, have a higher prevalence of Restless Legs Syndrome symptoms. Low iron levels can cause secondary Restless Legs Syndrome or aggravate symptoms of primary disease as well as diminish enzymatic activities that are involved in dopaminergic agonists production and the degradation of thyroid hormones. Moreover, as a result of low iron levels, dopaminergic agonists diminishes and thyroid hormones increase. Iron therapy improves Restless Legs Syndrome symptoms in iron deprived patients. Medical hypothesis. To discuss the theory that thyroid hormones, when not counterbalanced by dopaminergic agonists, may precipitate the signs and symptoms underpinning Restless Legs Syndrome. The main cause of Restless Legs Syndrome might be an imbalance between the dopaminergic agonists system and thyroid hormones.

Cytoprotective and suicidal signaling in oxidative stress

Oxidative stress is an imbalance between pro-oxidants and antioxidants in favor of the pro-oxidants, leading to different responses depending on the level of pro-oxidants achieved and the duration of exposure. In this article, we discuss the cytoprotective or suicidal signaling mechanisms associated with oxidative stress by addressing: (i) the development of an acute and mild pro-oxidant state by thyroid hormone administration eliciting the redox upregulation of the expression of proteins affording cell protection as a preconditioning strategy against ischemia-reperfusion liver injury; and (ii) the role of prolonged and severe oxidative stress and insulin resistance as determinant factors in the pathogenesis of non-alcoholic fatty liver disease associated with obesity.

Clinical implications of altered thyroid status in male testicular function: [review] / Implicações clínicas das alterações tireoidianas na função gonadal masculina: [revisão]

Thyroid hormones are involved in the development and maintenance of virtually all tissues. Although for many years the testis was thought to be a thyroid-hormone unresponsive organ, studies of the last decades have demonstrated that thyroid dysfunction is associated not only with abnormalities in morphology and function of testes, but also with decreased fertility and alterations of sexual activity in men. Nowadays, the participation of triiodothyronine (T3) in the control of Sertoli and Leydig cell proliferation, testicular maturation, and steroidogenesis is widely accepted, as well as the presence of thyroid hormone transporters and receptors in testicular cells throughout the development process and in adulthood. But even with data suggesting that T3 may act directly on these cells to bring about its effects, there is still controversy regarding the impact of thyroid diseases on human spermatogenesis and fertility, which can be in part due to the lack of well-controlled clinical studies. The current review aims at presenting an updated picture of recent clinical data about the role of thyroid hormones in male gonadal function.

Os hormônios da tireoide estão envolvidos virtualmente no desenvolvimento e na manutenção de todos os tecidos. As gônadas masculinas foram, por décadas, consideradas insensíveis aos hormônios tireoidianos. No entanto, estudos mais recentes têm demonstrado que disfunções tireoidianas estão associadas não somente a anormalidades na morfologia e na função dos testículos, mas também à diminuição da fertilidade e alterações na atividade sexual masculina. Atualmente, o papel da triiodotironina (T3) no controle da proliferação das células de Sertoli e Leydig, maturação testicular e esteroidogênese é amplamente aceito, bem como a presença de transportadores e receptores para o hormônio tireoidiano nos testículos durante o período de desenvolvimento e a idade adulta. No entanto, apesar dos dados que indicam que o T3 atua diretamente nos testículos humanos, persistem controvérsias em relação ao impacto das doenças tireoidianas sobre a espermatogênese e a fertilidade, o que pode ser em parte devido à escassez de estudos clínicos nessa área. Essa revisão tem por objetivo apresentar um panorama de dados clínicos atualizados sobre o papel dos hormônios tireoidianos na função gonadal masculina.

Inter-relações entre as funções hormonais do ovário e da tireoide / Interrelations between ovarian and thyroid functions

A relação entre as funções hormonais do ovário e da tireoide vem sendo motivo de interesse da comunidade científica mundial desde o século 19. Ao longo do tempo, diversos estudos objetivaram esclarecer fatos relacionados à interdependência funcional desses sistemas orgânicos. De fato, há evidências da ação direta e indireta do estrogênio na tireoide. Mulheres climatéricas em estado de hipoestrogenismo podem apresentar alterações na função tireoidea. Foram demonstrados efeitos da gonadectomia e da administração de estrogênio na tireoide de animais e de humanos. Por outro lado, alterações da função tireoidea podem causar distúrbios da função reprodutiva feminina. Mulheres portadoras de doenças da tireoide podem apresentar distúrbios menstruais, infertilidade e complicações do ciclo grávido-puerperal. Sendo assim, indicam-se procedimentos para a detecção de distúrbios tireoideos em diversas situações clínicas relacionadas à função reprodutiva feminina. Além disso, a função tireoidea deve ser cuidadosamente avaliada em mulheres com hipotireoidismo durante a gestação ou quando submetidas à estrogenioterapia. Dessa maneira, a função e as doenças da tireoide são assuntos de interesse para o ginecologista. É fundamental a conscientização do profissional que presta assistência à saúde da mulher em relação aos diversos aspectos relacionados às interações entre a tireoide e a função reprodutiva feminina.

Since the 19th century the interrelation between thyroid and sex organs function is recognized. In fact, there are evidences that estrogens act indirectly on the thyroid gland. Postmenopausal women can show altered thyroid function tests. It has been shown in animals and in humans that gonadectomy and estrogens treatment exert effects on thyroid gland. Also, thyroid dysfunction is associated with reproductive dysfunction in women. Both hyper and hypothyroidism may result in menstrual disturbances, infertility, abortion and complicated pregnancy. Tests for detection of thyroid disorders should be performed in women in many situations related to reproductive function. Patients with hypothyroidism should be strictly monitored during pregnancy and hormone replacement therapy with estrogens. Thus, thyroid dysfunction should be a point of interest for gynecologists. Practitioners providing health care for women should be aware of the consequences related to the interactions between these two endocrine systems .

Severe polyhydramnios associated with congenital hypothyroidism and hyponatraemia: a case report

This reports a case of congenital hypothyroidism associated with fetal polyhydramnios and severe neonatal hyponatremia. This patient is a premature 32- week infant who had poor oral feeding and severe hyponatremia that persisted till a diagnosis and treatment of hypothyroidism was established at the 37- week corrected age [5 weeks of age]. We here attempt to suggest another mechanism of polyhydramnios with hypothyroidism that is not linked to neck hyperextension. The relationship between poor feeding and swallowing in this patient and severe polyhydramnios was discussed. Literature review of the role of thyroid hormone in sodium homeostasis and urine output in relation to polyhydramnios was also discussed. This case report invites further research to understand the role of thyroid hormone in urine output and sodium homeostasis

O papel dos hormônios tireoidianos na função testicular: [revisão] / Thyroid hormones and testicular function: [review]

Os hormônios tireoidianos são essenciais para o crescimento, desenvolvimento e metabolismo. O pró-hormônio tiroxina (T4) é sintetizado e secretado pela glândula tireóide junto com uma pequena quantidade do hormônio ativo, a triiodotironina (T3). A conversão de T4 em T3 ocorre na periferia através da atividade das iodotironinas desiodases tipo 1 e tipo 2. Os efeitos biológicos dos hormônios tireoidianos são mediados pela interação do hormônio metabolicamente ativo (T3) com transportadores de membrana e receptores nucleares, resultando em ativação da transcrição gênica. Classicamente as gônadas eram consideradas refratárias aos hormônios tireoidianos. Estudos recentes, no entanto, têm demonstrado que o hormônio da tireóide desempenha um papel crítico no aparelho reprodutor, não somente durante o período de desenvolvimento, mas também na vida adulta. Neste artigo apresentamos uma revisão sobre o papel desempenhado pelos hormônios tireoidianos sobre a função testicular.

Thyroid hormones play an important role in the growth, development, and metabolism of mammalian tissues. The prohormone thyroxine (T4) is synthesized and secreted by the thyroid gland together with a small amount of the active hormone, triiodothyronine (T3). The iodothyronine deiodinases types 1 and 2 catalize the peripheral T4 to T3 conversion. To exert its biological effects T3 interact with specific membrane transporters and nuclear receptors, thus activating gene transcription. Classically, male gonads were considered to be unresponsive to thyroid hormones. Recent studies, however, have shown that thyroid hormones have a critical role in the male reproductive system, not only during development, but also in adult life. Hence, we review and discuss the most recent advances in our understanding of thyroid hormone effects in male gonadal function.

Abuso de esteróides anabolizantes e seu impacto sobre a função tireóidea: [revisão] / Abuse of anabolic steroids and its impact on thyroid function: [review]

A utilização de esteróides anabolizantes por indivíduos que desejam aumentar sua performance física, ou simplesmente para fins estéticos, tem atingido índices alarmantes nas últimas três décadas. Além dos efeitos desejados, uma infinidade de efeitos colaterais já foi bem descrita na literatura, como vários tipos de câncer, ginecomastia, peliosis hepatis, insuficiência renal, virilização, dentre outros. Sobre a função tireóidea, o efeito mais pronunciado em seres humanos é a diminuição da TBG, com conseqüente diminuição sérica de T3 e T4 totais, dependendo, porém, da susceptibilidade da molécula à aromatização e conseqüente transformação em estrógeno. Em ratos, o tratamento com esteróides anabolizantes altera a metabolização periférica dos hormônios tireóideos e também parece causar importante efeito proliferativo sobre as células tireóideas. Assim, o presente artigo visa rever os dados publicados acerca dos efeitos de doses suprafisiológicas de esteróides anabolizantes sobre a função tireóidea, reforçando o perigo que a utilização indiscriminada dessas drogas pode causar à saúde.

The use of anabolic steroids to increase physical performance and for aesthetic ends has reached alarming indices in the last three decades. Besides the desired actions, several collateral effects have been described in the literature, such as the development of some types of cancer, ginecomasty, peliosis hepatis, renal insufficiency, virilization, amongst others. The most proeminent effect on human thyroid function is the reduction of thyroxine binding globulin (TBG), with consequent reductions of total serum T3 and T4, depending however on the susceptibility of the drug to aromatization and subsequent transformation into estrogen. In rats, anabolic steroids also act in the peripheral metabolism of thyroid hormones and seem to exert an important proliferative effect on thyroid cells. Thus, the aim of the present paper is to review data on the effect of supraphysiological doses of anabolic steroids on thyroid function, showing the danger that indiscriminate use of these drugs can cause to health.

Hipotireoidismo na criança: diagnóstico e tratamento: [revisão] / Hypothyroidism in children: diagnosis and treatment: [review]

OBJETIVO: Apresentar dados relevantes e atualizados referentes ao quadro de hipotireoidismo do recém-nascido ao adolescente. FONTES DE DADOS: Artigos, revisões e livros contendo informações atualizadas e de interesse. SÍNTESE DOS DADOS:Esta revisão aborda dados sobre etiopatogenia do hipotireoidismo. A triagem para o hipotireoidismo congênito é importante para o diagnóstico e tratamento precoce do recém-nascido. Aponta as dificuldades na conduta do hipotireoidismo subclínico. Destaca a importância do diagnóstico da tireoidite auto-imune de Hashimoto, sua alta incidência entre os adolescentes, principalmente meninas, e a existência de um quadro neurológico grave, a encefalopatia de Hashimoto. Aponta para situações em que o hipotireoidismo grave pode levar a distúrbios da puberdade com situações de precocidade e retardo puberal. Descreve a importância dos fatores de transcrição na embriogênese da tireóide. Critérios diagnósticos e terapêuticos são abordados. CONCLUSÃO: Os hormônios tireoidianos são necessários para o crescimento e desenvolvimento normal desde a vida fetal. Sua produção insuficiente ou sua ação inadequada em nível celular ou molecular levam ao hipotireoidismo. Esses hormônios são necessários para o desenvolvimento do cérebro na vida fetal e pós-natal. Neonatologistas e pediatras deparam-se com problemas do desenvolvimento da criança, muitos dos quais já começam em vida intra-uterina. Atualmente, com a triagem neonatal, neonatologistas e pediatras podem evitar danos irreversíveis com tratamento precoce. Também devem estar atentos para disfunções como as do hipotireoidismo subclínico e tireoidite de Hashimoto, que podem provocar danos não só no crescimento, mas também no desenvolvimento neurológico e psicológico destas crianças e adolescentes.

OBJECTIVE:To present relevant and updated information on the status of hypothyroidism in the pediatric population (newborn infants to adolescents). SOURCES: Original and review articles and books containing relevant updated data. SUMMARY OF THE FINDINGS: This review addressed data on the etiopathogeny of hypothyroidism and on the importance of screening for congenital hypothyroidism to assure early diagnosis and treatment of the newborn. We point out the difficulties experienced in the handling of subclinical hypothyroidism; we also address the importance of diagnosing autoimmune Hashimoto's thyroiditis, the high incidence of the disease among adolescents, mainly females, and the occurrence of a severe neurological condition, Hashimoto's encephalopathy. We indicate situations in which severe hypothyroidism may lead to puberty disorders (precocious or delayed puberty) and describe the importance of transcription factors in thyroid embryogenesis. Diagnostic and therapeutic criteria are also addressed. CONCLUSION: Thyroid hormones are necessary for normal growth and development since fetal life. Insufficient production or inadequate activity on the cellular or molecular level lead to hypothyroidism. These hormones are necessary for the development of the brain in the fetus and in the newborn infant. Neonatologists and pediatricians deal with child development issues in their practice, and many of these issues start during intrauterine life. Currently, with neonatal screening, neonatologists and pediatricians can prevent irreversible damage through early treatment. They should also be alert for dysfunctions such as subclinical hypothyroidism and Hashimoto's thyroiditis, which may provoke damage not only to growth, but also to the neurological and psychological development of these children and adolescents.

Hipotiroidismo neonatal: fisiopatogenia, aspectos moleculares, metabólicos y clínicos / Neonatal hypothyroidism: Pathophysiogenic, molecular and clinical aspects

This review provides an updated summary on both the clinical and diagnostic aspects of neonatal hypothyroidism (NeH); as well as on the molecular and pathophysiologic processes known to be involved in the installment of this important hormonal deficiency. Current information regarding its etiology and pathogenesis has allowed classigying NeH in three major groups: endemic, transient, and sporadic hypothyroidism. The later corresponds to congenital hypothyroidism and encompasses a broad spectrum of hereditary disorders causing hypothyroidism in newborns and young children. These congenital disorders include hypothalamic-pituitary or thyroid dysgenesis and/or dyshormonogenesis, as well as hyporesponsiveness or resistance to either TRH, TSH or to thyroid hormones. The introduction of national screening programs for NeH have overcome the difficulties in the early diagnosis thus helping to prevent its serious and irreversible consequences on intellectual and physical development. Concomitantly, an increase in the need for complementary etiologic and molecular diagnosis has risen. The current capability to perform a fine and precise diagnose is crucial both for treatment of the affected infant and for genetic counseling of the family. Although incomplete, available epidemiological information in Mexico indicates that NeH prevalence can be as high as twice that in other developed world countries. On these bases, national public health policies and epidemiological surveyance must be strengthen not only to identify, diagnose and timely treat, but to prevent and eradicate endemic NeH.

Este trabajo revisa algunos aspectos del conocimiento actual sobre la fisiopatogenia, los hallazgos clínicos y el diagnóstico bioquímico y molecular del hipotiroidismo neonatal (HNe). El término HNe denota un conjunto de entidades clínicamente pleomórficas, que invariablemente cursan con una disminución en el aporte; o bien, en la disponibilidad celular y/o en la respuesta a las hormonas tiroideas (HT) durante la etapa perinatal. Las HT o yodotironinas son indispensables para la morfogénesis y maduración funcional normal de prácticamente todos los tejidos en el organismo, y su participación es crucial en el caso del sistema nervioso. La información actual permite realizar una clasificación del HNe tanto en términos etio y fisiopatogénicos, como en el contexto del substrato genético que los determina. Así, se reconocen tres grandes tipos de HNe: el endémico, el transitorio y el esporádico. Este último grupo de HNe incluye los defectos hipotálamo-hipofisiarios, los trastornos ontogenéticos o disgenesias tiroideas, la resistencia periférica a las HT y las dishormonogénesis. Por otra parte, en la comunidad internacional existe una creciente preocupación por la contaminación ambiental debida a órgano-halógenos antropogénicos. Estos compuestos han mostrado su potencial como agentes distiroideos en animales de experimentación y en algunos estudios clínicos. En México, tanto la distribución geográfica y prevalencia del HNe, como la deficiencia de yodo y otros micronutrimentos en la dieta, se han analizado de manera esporádica y no sistemática. Aunque incompleta, la información disponible sugiere que en nuestro país la prevalencia de HNe es sensiblemente mayor que la reportada mundialmente. Contar con información completa y confiable acerca de estos aspectos no es trivial, puesto que su conocimiento permitirá establecer políticas razonadas de salud pública para identificar, diagnosticar y tratar oportunamente el padecimiento; así como para prevenir y erradicar el HNe endémico.

Predictive value of thyroid hormones on the first day in adult respiratory distress syndrome patients admitted to ICU: comparison with SOFA and APACHE II scores

Thyroid hormone dysfunction could affect outcome and increase mortality in critical illness. Therefore, in a prospective, observational study we analyzed and compared the prognostic accuracy of free tri-iodothyronine [fT3], free thyroxine [fT4], thyroid-stimulating hormone [TSH], along with the APACHE II and SOFA scoring systems in predicting intensive care unit [ICU] mortality in critically ill patients. Physiology scores were calculated for the first 24 hours after ICU admission in 206 patients with acute respiratory distress syndrome. APACHE II and SOFA scores were employed to determine the initial severity of illness. Thyroid hormones were measured within the first 24 hours. Logistic regression models were created for APACHE II scores, SOFA scores, and thyroid hormone levels. The models predicted high- and low-risk subgroups. Models that showed a good fit were stratified by Kaplan-Meier survival curves. There were 98 [47.6%] survivors and 108 [52.4%] non-survivors. The survivors had a lower APACHE II score [11.50 vs 15.82, P<0.0005], a lower SOFA score [6.06 vs 9.42, P<0.0005], a younger age [57 vs 70 years, P=0.008], a shorter ICU stay [13 vs 16 days, P=0.012], and a higher fT3 level [2.18 vs 1.72 pg/mL, P=0.002] than non-survivors. ICU survival was most closely predicted by a model that included age and fT3 and a model that included APACHE II and APACHE II*sex. In critically ill patients, serum fT3 concentrations markedly decreased after ICU admission among non-survivors. According to our findings, fT3 levels might have additive discriminatory power to age, SOFA and APACHE II scores in predicting short-term mortality in ARDS patients admitted to ICU