About 10% of hyperthyroid cats have a normal total T4 (TT4), requiring further testing to make the diagnosis. Thyroid stimulating hormone (TSH) is measured using the "canine" assay (TSH-CLIA, Immulite 2000 by Siemens) as the only assay currently available. However, this assay cannot differentiate between subnormal and low-normal TSH concentrations in cats due to poor specificity (70-85%). A novel feline-optimized TSH assay (TSH-BAW, Truforma by Zomedica) was recently developed. It allows differentiation between euthyroid and hyperthyroid cats. However, the effect of non-thyroidal illness (NTI) on TSH-BAW has not been evaluated. Our objectives included the comparison of serum TSH concentration using both the TSH-CLIA and TSH-BAW assays among hyperthyroid cats, cats with NTI, and healthy cats, and the evaluation of the sensitivity and specificity of the TSH-BAW for diagnosis of FHT. This prospective cross-sectional study was performed on 102 client-owned cats, including 37 hyperthyroid, 33 healthy, and 32 NTI cats. The following thyroid hormones were measured in all cats: TT4, TSH with both assays (Immulite 2000 and Truforma). Hyperthyroidism was confirmed by thyroid scintigraphy. Euthyroidism was confirmed by repeating TT4 measurement at least three months after enrollment (if available) to rule out subclinical hyperthyroidism. Cats with NTI were further divided based on the severity of their illness. Serum TSH was compared among groups using Kruskal-Wallis followed by Dunn's procedure, and compared among NTI severity scores using the Fisher's Exact test. Significance was set at P <0.05. The sensitivity and specificity of TSH-BAW for detecting hyperthyroidism are 78% (62-90%) and 97% (84-100%), respectively. The median TSH is significantly different between hyperthyroid cats and healthy and NTI cats with both assays (P<0.01). The TSH was not different between the latter euthyroid groups (P=0.87 and P=0.29). Eight (21.6%) hyperthyroid cats have a normal TSH-BAW but undetectable TSH-CLIA. Twelve (4 healthy, 8 NTI) euthyroid cats (18.5%) have an undetectable TSH-CLIA with only two (1 healthy, 1 NTI) (3%) having an undetectable TSH-BAW. The proportion of cats with a suppressed TSH is higher with severe illnesses with the TSH-CLIA only. In conclusion, the TSH-BAW has a high specificity, identifies normal TSH in healthy cats more often, and appears to not be affected by NTI. It can be a useful tool for the diagnosis of feline hyperthyroidism. However, a low-normal TSH cannot be used to rule out hyperthyroidism. / Master of Science / Hyperthyroidism leads to elevation of the thyroid hormone total T4 (TT4). About 10% of hyperthyroid cats have a normal TT4, requiring further testing to make the diagnosis. Another thyroid hormone, thyroid stimulating hormone (TSH), could be used like it is with people. In feline medicine, it is measured using the "canine" assay (TSH-CLIA, Immulite 2000 by Siemens) as the only assay currently available. However, this assay cannot differentiate between subnormal and low-normal TSH concentrations in cats due to poor specificity (70-85%). A novel feline-optimized TSH assay (TSH-BAW, Truforma by Zomedica) was recently developed. It allows differentiation between euthyroid and hyperthyroid cats. However, the effect of non-thyroidal illness (NTI) on TSH-BAW has not been evaluated. Our objectives included the comparison of serum TSH concentration using both the TSH-CLIA and TSH-BAW assays among hyperthyroid cats, cats with NTI, and healthy cats, and the evaluation of the sensitivity and specificity of the TSH-BAW for diagnosis of FHT. The study was performed on 102 client-owned cats, including 37 hyperthyroid, 33 healthy, and 32 NTI cats. The following thyroid hormones were measured in all cats: TT4, TSH with both assays (Immulite 2000 and Truforma). Cats with NTI were further divided based on the severity of their illness. Serum TSH was compared among groups using Kruskal-Wallis followed by Dunn's procedure, and compared among NTI severity scores using the Fisher's Exact test. Significance was set at P <0.05. The sensitivity and specificity of TSH-BAW are 78% and 97%, respectively. The median TSH is significantly different between hyperthyroid cats and healthy and NTI cats with both assays. The euthyroid cats (healthy and NTI cats) were not different. Eight (21.6%) hyperthyroid cats have a normal TSH-BAW (not normal in the face of hyperthyroidism) but undetectable TSH-CLIA. The proportion of euthyroid cats with a suppressed TSH (not normal in the face of euthyroidism) is higher with the TSH-CLIA compared to the TSH-BAW. Only with the TSH-CLIA, the proportion of NTI cats with a suppressed TSH is higher than healthy cats, and is higher with severe illnesses. In conclusion, the TSH-BAW has a high specificity, identifies normal TSH in healthy cats more often, and appears to not be affected by NTI. It can be a useful tool for the diagnosis of feline hyperthyroidism. However, a low-normal TSH cannot be used to rule out hyperthyroidism.

Made available in DSpace on 2014-06-12T18:28:00Z (GMT). No. of bitstreams: 2 arquivo7904_1.pdf: 1266782 bytes, checksum: ae430a4a9cbd5ba3771d8e14df2fa3a1 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2006 / O hipertireoidismo da Doença de Graves, a forma mais comum de hipertireoidismo, é causado por auto-anticorpos que ativam o receptor do TSH. Associa-se com aumento da mortalidade cardiovascular e fraturas de colo de fêmur em idosas. As opções terapêuticas atualmente disponíveis são as drogas antitireoidianas, a cirurgia e o radioiodo, sendo nenhuma delas considerada ideal pois não atuam diretamente na etiopatogênese da doença. O radioiodo vem sendo cada vez mais utilizado como primeira escolha, sendo um tratamento definitivo, seguro e de fácil administração. A utilização de doses calculadas não traz nenhum benefício, comparando com às doses fixas. Há autores que preferem doses mais altas para induzir deliberadamente o hipotireoidismo, e outros doses mais baixas, com menor incidência de hipotireoidismo e maior de eutireoidismo. Não há consenso sobre o melhor esquema de doses fixas a ser utilizado, sendo esse o principal enfoque deste trabalho. Foram avaliados, pacientes com hipertireoidismo por Doença de Graves atendidos no Serviço de Endocrinologia do Hospital das Clínicas da Universidade Federal de Pernambuco, submetidos ao radioiodo com doses de 10 e 15 mCi no Serviço de Medicina Nuclear do referido hospital, no período de janeiro de 2000 a dezembro de 2002. Foi analisada a função tireoidiana e a associação entre idade, procedência e uso prévio de drogas antitireoidianas com 6, 12 e 24 meses após o radioiodo. Os resultados finais foram expressos pela média dos valores obtidos, quando então, foram os grupos comparados entre si. Dos 164 pacientes analisados, 61 (37,2%) foram submetidos a 10 mCi e 103 (62,8%) a 15 mCi. Na análise longitudinal observou-se que a remissão do hipertireoidismo foi estatisticamente diferente no 6º mês (p<0,001), sendo maior no grupo que foi empregada a dose de 15 mCi; mas, foi semelhante nos grupos nos 12º e 24º meses. É possível concluir que doses fixas de 10 e 15 mCi, promovem semelhante remissão do hipertireoidismo após 12 meses de tratamento. A remissão do hipertireoidismo não teve associação com a idade, sexo e uso prévio de drogas antitireoidianos

Os hormônios tireoidianos (HTs) participam de diversos processos biológicos por meio de ações que exercem na expressão de genes que codificam proteínas envolvidas no metabolismo, crescimento e desenvolvimento. O objetivo desse trabalho foi caracterizar ações genômicas e não genômicas dos HT no eixo hipotálamo-hipófise-adrenal. Detectamos nos ratos tireoidectomizados (Tx) uma redução do conteúdo de mRNA da POMC, em paralelo a um aumento de sua cauda poli(A) e de sua taxa de tradução. T3 em dose suprafisiológica por 30 minutos ou 5 dias promoveu aumento na expressão desse mRNA e o conteúdo proteico de POMC/ACTH permaneceu inalterado. A enzima PC1 teve sua expressão aumentada em ratos Tx, fato revertido pelo tratamento com T3. As enzimas esteroidogênicas e a corticosterona sérica não apresentaram diferenças nos grupos estudados in vivo, apesar da redução sérica de ACTH em animais Tx, porém SF1 teve sua expressão aumentada in vitro após tratamento com T3. Na cultura de hipófises, o TSH se mostrou capaz de aumentar AMPc e Ca2+ citosólico promovendo a secreção de ACTH. / Thyroid hormones (TH) participate in many biological processes promoting the expression of genes that encode proteins involved in the metabolism, growth and development. The aim of this study was to characterize genomic and non genomic actions of TH in the hypothalamic-pituitary-adrenal axis. We detected in thyroidectomized (Tx) rats a reduction of POMC mRNA content in parallel to an increase of its poli(A) tail and its translation rate. Supraphysiological doses of T3 for 30 minutes or 5 days injections increased the expression of this mRNA, although POMC/ACTH protein content remained unchanged. PC1 enzyme had its expression increased in Tx rats, which was reversed back to control levels after T3 treatment. Steroidogenic enzymes and serum corticosterone did not show any differences in the groups studied in vivo, despite the reduction of serum ACTH in Tx animals, but SF-1 had its in vitro expression increased after treatment with T3. In pituitary primary culture, TSH promoted increase in cAMP and cytosolic Ca2+ concentration stimulating ACTH secretion.

Le diagnostic précoce de l'hypothyroïdie permet d'initier le traitement au plus tôt et ainsi de préserver la santé du patient. Le bénéfice du traitement de l'hypothyroïdie franche a été depuis longtemps établi, mais les critères de prise en charge des patients en hypothyroïdie fruste sont encore difficiles à définir. En effet, les symptômes ne sont pas toujours présents et leur appréciation est subjective. Afin d'établir le diagnostic et la prise en charge, le médecin s'appuie sur le dosage de la thyréostimuline (TSH) dans le sang, qui peut éventuellement être complété par le dosage des hormones thyroïdiennes. Le dosage de la TSH, très sensible, peut présenter sur un même échantillon sanguin d'importantes variations qui rendent d'autant plus difficiles la décision du médecin et le suivi du patient. Le polymorphisme naturel de la TSH peut expliquer en partie ces variations. La TSH appartient en effet à la famille des hormones glycoprotéiques et sa glycosylation peut constituer jusqu'à 30% de son poids. Dans le cas de l'hypothyroïdie en particulier, ces glycanes sont modifiés et présentent une plus grande quantité d'acides sialiques terminaux. Ainsi, certaines variations entre les dosages de la TSH, qui freinent actuellement leur harmonisation, peuvent être dues à des différences de reconnaissance de glycoformes par les anticorps utilisés dans les dosages. Dans ce contexte, l'objectif de de ces travaux était de contribuer à la construction de dosages plus performants que ceux actuellement utilisés dans le diagnostic de l'hypothyroïdie. Un nouveau calibrateur recombinant sialylé plus proche de la TSH circulante dans l'hypothyroïdie a alors été produit. De nouvelles associations d'anticorps monoclonaux ont été utilisées pour construire des dosages. Les nouveaux dosages sélectionnés ont ensuite été calibrés avec la TSH sialylée produite et le calibrateur de référence international. Ils ont alors servi à doser plusieurs séries de sérums de patients. Ces travaux ont donc validé l'utilisation d'un nouveau calibrateur d'origine recombinante pour les dosages de la TSH, ce qui devrait à l'harmonisation des dosages existants. / If iodine deficiency is the first cause of low thyroid hormone levels in the world, there are also other etiologies to thyroid disorders. Diagnosis of those allow an early treatment to preserve patient's health. Although there is a general agreement concerning treatment of overt hypothyroidism, treatment of subclinical hypothyroidism is still under debate. In these cases, symptoms are, by definition, not always present. In order to establish diagnosis, the clinicians rely on the measurement of circulating thyroid stimulating hormone (TSH, potentially completed with thyroid hormones measurement). TSH assays are now very sensitive, but can present important between assays variations. The diagnosis and follow up of the patient are consequently complicated. Natural polymorphism of TSH can explain a part of this variability. TSH belongs to the glycoprotein hormones family and its glycans can count for more than 30% of its weight. In hypothyroidism, these glycans are subject of modulation and present higher levels of terminal sialylation. Variation in immuno-assays can be explained by these modifications of sialylation if recognition by antibodies used in immuno-assays is glycosylation dependent. In this context, the aim of this work was to contribute to the construction of new immuno-assays, more reliable in the early diagnosis of subclinical hypothyroidism. During this thesis a new recombinant standard closer to circulating TSH was produced. The total level of sialylation was higher and better mimic the circulating forms in hypothyroidism. In order to select the best antibodies associations in immuno-assays, new antibodies were obtained and associated with commercially available antibodies. New immuno assays improvement is based on the following two approaches: the first one is the use of a new standard which presents glycoformes closer to the circulating TSH and the second one consists in an appropriate selection of antibodies involved in the assays. The new assays were used to measure TSH concentration in blood samples. These studies associated with validation steps allow us to select four assays and constitute a proof of concept for the use of a new sialylated recombinant standard for TSH assays. This can contribute to the needed harmonization of TSH assays.

Le diagnostic précoce de l'hypothyroïdie permet d'initier le traitement au plus tôt et ainsi de préserver la santé du patient. Le bénéfice du traitement de l'hypothyroïdie franche a été depuis longtemps établi, mais les critères de prise en charge des patients en hypothyroïdie fruste sont encore difficiles à définir. En effet, les symptômes ne sont pas toujours présents et leur appréciation est subjective. Afin d'établir le diagnostic et la prise en charge, le médecin s'appuie sur le dosage de la thyréostimuline (TSH) dans le sang, qui peut éventuellement être complété par le dosage des hormones thyroïdiennes. Le dosage de la TSH, très sensible, peut présenter sur un même échantillon sanguin d'importantes variations qui rendent d'autant plus difficiles la décision du médecin et le suivi du patient. Le polymorphisme naturel de la TSH peut expliquer en partie ces variations. La TSH appartient en effet à la famille des hormones glycoprotéiques et sa glycosylation peut constituer jusqu'à 30% de son poids. Dans le cas de l'hypothyroïdie en particulier, ces glycanes sont modifiés et présentent une plus grande quantité d'acides sialiques terminaux. Ainsi, certaines variations entre les dosages de la TSH, qui freinent actuellement leur harmonisation, peuvent être dues à des différences de reconnaissance de glycoformes par les anticorps utilisés dans les dosages. Dans ce contexte, l'objectif de de ces travaux était de contribuer à la construction de dosages plus performants que ceux actuellement utilisés dans le diagnostic de l'hypothyroïdie. Un nouveau calibrateur recombinant sialylé plus proche de la TSH circulante dans l'hypothyroïdie a alors été produit. De nouvelles associations d'anticorps monoclonaux ont été utilisées pour construire des dosages. Les nouveaux dosages sélectionnés ont ensuite été calibrés avec la TSH sialylée produite et le calibrateur de référence international. Ils ont alors servi à doser plusieurs séries de sérums de patients. Ces travaux ont donc validé l'utilisation d'un nouveau calibrateur d'origine recombinante pour les dosages de la TSH, ce qui devrait à l'harmonisation des dosages existants. / If iodine deficiency is the first cause of low thyroid hormone levels in the world, there are also other etiologies to thyroid disorders. Diagnosis of those allow an early treatment to preserve patient's health. Although there is a general agreement concerning treatment of overt hypothyroidism, treatment of subclinical hypothyroidism is still under debate. In these cases, symptoms are, by definition, not always present. In order to establish diagnosis, the clinicians rely on the measurement of circulating thyroid stimulating hormone (TSH, potentially completed with thyroid hormones measurement). TSH assays are now very sensitive, but can present important between assays variations. The diagnosis and follow up of the patient are consequently complicated. Natural polymorphism of TSH can explain a part of this variability. TSH belongs to the glycoprotein hormones family and its glycans can count for more than 30% of its weight. In hypothyroidism, these glycans are subject of modulation and present higher levels of terminal sialylation. Variation in immuno-assays can be explained by these modifications of sialylation if recognition by antibodies used in immuno-assays is glycosylation dependent. In this context, the aim of this work was to contribute to the construction of new immuno-assays, more reliable in the early diagnosis of subclinical hypothyroidism. During this thesis a new recombinant standard closer to circulating TSH was produced. The total level of sialylation was higher and better mimic the circulating forms in hypothyroidism. In order to select the best antibodies associations in immuno-assays, new antibodies were obtained and associated with commercially available antibodies. New immuno assays improvement is based on the following two approaches: the first one is the use of a new standard which presents glycoformes closer to the circulating TSH and the second one consists in an appropriate selection of antibodies involved in the assays. The new assays were used to measure TSH concentration in blood samples. These studies associated with validation steps allow us to select four assays and constitute a proof of concept for the use of a new sialylated recombinant standard for TSH assays. This can contribute to the needed harmonization of TSH assays.

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Thyrotropin (TSH) binds to TSH receptors on thyrocytes to regulate development and growth of the thyroid gland, and to stimulate thyroid hormone production. Thyrotropin has also been shown to act in an extra-thyroidal fashion, and to engage TSH receptors on adipocytes to induce lipolysis, similar to the response seen by stimulation with β-adrenergic receptor agonists (i.e. isoproterenol). In both cell types, cAMP-dependent kinase (PKA) is activated. Recently, PRAJA2, a novel AKAP and E3 ubiquitin ligase that targets the regulatory subunits of PKA was identified. The ubiquitin-dependent proteasomal degradation of the PKA regulatory subunits, due to PKA- phosphorylated PRAJA2, prolongs the catalytic activity of PKA, as shown in neuroblastoma cells by Lignitto et al., 2011. In adipocytes, stimulated PKA activity is required for lipolysis. Additionally, PRAJA2 has been described to have increased expression in TSH-responsive, differentiated thyroid cancer cells when compared to anaplastic thyroid tumor (Cantara et al., 2012) The aim of this study was to characterize PRAJA2 and its potential influence on adipocyte lipolysis. These data confirm that TSH and isoproterenol stimulate lipolysis in primary human differentiated adipocytes. PRAJA2 is expressed at the mRNA and protein level in differentiated adipocytes, with no change following stimulation with TSH or isoproterenol. Stimulation with isoproterenol, but not TSH, increases PKA-dependent phosphorylation of a 122kDa (potentially PRAJA2) and 69kDa protein identified in PRAJA2 immunoprecipitates. These proteins may prove important for lipolytic signaling or other PRAJA2-dependent process in adipocytes. Experimentation was unable to identify interactions between PRAJA2 and PKAR2 in differentiated adipocytes; however further investigations are required before discounting this interaction. An attempt was made to knockdown PRAJA2 in this model, and measure effects on lipolytic response; however, this was unsuccessful. Taken together, PRAJA2 appears to be phosphorylated following β-adrenergic stimulation in human adipocytes; however, further studies are needed to delineate the specific role of PRAJA2 in this human differentiated adipocyte model.

No description available.

Residente de 3º año de Medicina Nuclear, Hospital Clínico de la Universidad de Chile, Servicio de Medicina Nuclear, Departamento de Medicina / INTRODUCCIÓN: El cáncer diferenciado de tiroides (CDT) es la neoplasia maligna más frecuente del sistema endocrino. Su tratamiento incluye frecuentemente yodo radiactivo, el cual puede producir efectos secundarios indeseados. Actualmente existe controversia respecto a la indicación y actividad de radioyodo a administrar. OBJETIVO: Evaluar los efectos secundarios a corto y mediano plazo del tratamiento con 131I en pacientes con CDT y su relación con la actividad administrada; además, determinar la concordancia de las dosis indicadas localmente versus lo recomendado por la Guía ATA 2015. MATERIALES Y MÉTODOS: Estudio prospectivo, que incluyó pacientes con CDT que ingresaron al Servicio de Medicina Nuclear del Hospital Clínico de la Universidad de Chile para tratamiento con radioyodoterapia posterior a tiroidectomía total. Se valoró la aparición de efectos secundarios a corto y mediano plazo a través de una encuesta, en 2 oportunidades: dentro de los 10 primeros días post radioyodo y a los 6 meses post terapia. Además, se catalogó a cada paciente según riesgo de recurrencia y se estableció la concordancia de la indicación de 131I con la Guía ATA 2015. RESULTADOS: Los síntomas secundarios más frecuentes a corto plazo fueron las náuseas (59 pacientes), dolor cervical (44 pacientes) y disgeusia (43 pacientes); mientras que a corto plazo fue la disgeusia (16 pacientes) xerostomía (9 pacientes) y sialoadenitis (7 pacientes). Existe una relación directamente proporcional entre la ocurrencia de efectos secundarios y la actividad administrada de yodo radiactivo. Hubo buena concordancia de riesgo de recurrencia vs indicación de 131I en los pacientes de riesgo intermedio y alto, a diferencia de los pacientes de bajo riesgo, en que se observó frecuentemente indicación de mayor actividad a la recomendada. CONCLUSIONES: Los efectos secundarios a la radioyodoterapia en los pacientes con CDT son frecuentes, habitualmente de corta duración y autolimitados. Existe cierta heterogeneidad en los criterios de indicación de 131I, especialmente en los casos de bajo riesgo.