Synergic actions of polyphenols and cyanogens of peanut seed coat (Arachis hypogaea) on cytological, biochemical and functional changes in thyroid.

In animals, long-term feeding with peanut (Arachis hypogaea) seed coats causes hypertrophy and hyperplasia of the thyroid gland. However, to date there have been no detailed studies. Here, we explored the thyroidal effects of dietary peanut seed coats (PSC) in rats. The PSC has high levels of pro-goitrogenic substances including phenolic and other cyanogenic constituents. The PSC was mixed with a standard diet and fed to rats for 30 and 60 days, respectively. Animals fed with the PSC-supplemented diet showed a significant increase in urinary excretion of thiocyanate and iodine, thyroid enlargement, and hypertrophy and/or hyperplasia of thyroid follicles. In addition, there was inhibition of thyroid peroxidase (TPO) activity, 5’-deiodinase-I (DIO1) activity, and (Na+-K+)-ATPase activity in the experimental groups of rats as compared to controls. Furthermore, the PSC fed animals exhibited decreased serum circulating total T4 and T3 levels, severe in the group treated for longer duration. These data indicate that PSC could be a novel disruptor of thyroid function, due to synergistic actions of phenolic as well as cyanogenic constituents.

Neonatal hyper- and hypothyroidism alter the myoglobin gene expression program in adulthood

Myoglobin acts as an oxygen store and a reactive oxygen species acceptor in muscles. We examined myoglobin mRNA in rat cardiac ventricle and skeletal muscles during the first 42 days of life and the impact of transient neonatal hypo- and hyperthyroidism on the myoglobin gene expression pattern. Cardiac ventricle and skeletal muscles of Wistar rats at 7-42 days of life were quickly removed, and myoglobin mRNA was determined by Northern blot analysis. Rats were treated with propylthiouracil (5-10 mg/100 g) and triiodothyronine (0.5-50 µg/100 g) for 5, 15, or 30 days after birth to induce hypo- and hyperthyroidism and euthanized either just after treatment or at 90 days. During postnatal (P) days 7-28, the ventricle myoglobin mRNA remained unchanged, but it gradually increased in skeletal muscle (12-fold). Triiodothyronine treatment, from days P0-P5, increased the skeletal muscle myoglobin mRNA 1.5- to 4.5-fold; a 2.5-fold increase was observed in ventricle muscle, but only when triiodothyronine treatment was extended to day P15. Conversely, hypothyroidism at P5 markedly decreased (60%) ventricular myoglobin mRNA. Moreover, transient hyperthyroidism in the neonatal period increased ventricle myoglobin mRNA (2-fold), and decreased heart rate (5%), fast muscle myoglobin mRNA (30%) and body weight (20%) in adulthood. Transient hypothyroidism in the neonatal period also permanently decreased fast muscle myoglobin mRNA (30%) and body weight (14%). These results indicated that changes in triiodothyronine supply in the neonatal period alter the myoglobin expression program in ventricle and skeletal muscle, leading to specific physiological repercussions and alterations in other parameters in adulthood.

Disfunção tiróidea e amiodarona / Thyroid dysfunction and amiodarone

Apesar de a maioria dos doentes tratados com amiodarona permanecer em eutiroidia, alguns desenvolvem hipertiroidismo (HPEIA) ou hipotiroidismo (HPOIA) induzidos pela amiodarona. Os autores apresentam uma análise retrospectiva dos processos de dez doentes com disfunção tiróidea induzida pela amiodarona. Verificou-se que seis doentes eram mulheres e que o tempo médio de toma da amiodarona foi de 17,7 meses. O HPOIA foi o mais frequente (seis doentes). Dos doentes com HPEIA, dois tinham HPEIA tipo 2, um tipo 1 e um tipo 3. Sintomas sugestivos de disfunção tiróidea ocorreram em cinco doentes, a maioria com HPOIA. No HPEIA, a clínica mais comum foi exacerbação da arritmia de base (três doentes). A interrupção da amiodarona e administração de levotiroxina foi a terapêutica escolhida em 83,3% dos casos de HPOIA, enquanto a tionamida associada a corticoide com suspensão da amiodarona foi opção em 75% dos casos de HPEIA. Registraram-se três óbitos, todos com HPEIA. O HPEIA constituiu uma complicação potencialmente fatal. A clínica pode ser vaga, pelo que a monitorização da função tiróidea é obrigatória.

Although most patients remain clinically euthyroid, some develop amiodarone-induced hyperthyroidism (HPEAI) or hypothyroidism (HPOAI). The authors present a retrospective analysis of ten patients with amiodarone-induced thyroid dysfunction. Six patients were female and mean amiodarone intake was 17.7 months. HPOIA was more common (six patients). From all the patients with HPEAI, two had type 2, one had type 1, and one had type 3 hyperthyroidism. Symptoms suggestive of thyroid dysfunction occurred in five patients, most of them with HPOAI. In HPEAI, the most frequent symptom was exacerbation of arrhythmia (three patients). Discontinuation of amiodarone and treatment with levothyroxine was chosen in 83.3% of the HPOAI cases, while thyonamide treatment with corticosteroids and without amiodarone was the option in 75% of the HPEAI cases. There were three deaths, all in patients with HPEAI. HPEAI is potentially fatal. The clinical picture may be vague, so the thyroid monitoring is mandatory.

Alternative complement pathway and factor B activities in rats with altered blood levels of thyroid hormone

Evaluating the activity of the complement system under conditions of altered thyroid hormone levels might help elucidate the role of complement in triggering autoimmune processes. Here, we investigated alternative pathway (AP) activity in male Wistar rats (180 ± 10 g) after altering their thyroid hormone levels by treatment with triiodothyronine (T3), propylthiouracil (PTU) or thyroidectomy. T3 and thyroxine (T4) levels were determined by chemiluminescence assays. Hemolytic assays were performed to evaluate the lytic activity of the AP. Factor B activity was evaluated using factor B-deficient serum. An anti-human factor B antibody was used to measure factor B levels in serum by radial immunodiffusion. T3 measurements in thyroidectomized animals or animals treated with PTU demonstrated a significant reduction in hormone levels compared to control. The results showed a reduction in AP lytic activity in rats treated with increasing amounts of T3 (1, 10, or 50 µg). Factor B activity was also decreased in the sera of hyperthyroid rats treated with 1 to 50 µg T3. Additionally, treating rats with 25 µg T3 significantly increased factor B levels in their sera (P < 0.01). In contrast, increased factor B concentration and activity (32 percent) were observed in hypothyroid rats. We conclude that alterations in thyroid hormone levels affect the activity of the AP and factor B, which may in turn affect the roles of AP and factor B in antibody production.

Virus C genotype predisposes to primary hypothyroidism during interferon-α treatment for chronic hepatitis C

OBJECTIVE: The treatment of the chronic hepatitis C (HCV) with α-interferon is associated with thyroid dysfunction (TD). The aim of this study was to evaluate thyroid function outcome among patients with chronic HCV under treatment with conventional interferon (IFN) or peguilated interferon (PEG-IFN) in association with ribavirin. PATIENTS AND METHODS: We studied 293 patients with chronic HCV, submitted to drug therapy for 24 or 48 weeks. Initially, we evaluated FT4, TSH, TPOAb, TgAb, and continued to monitor FT4 and TSH every three months during therapy and six months thereafter. RESULTS: At baseline, TD prevalence was 6.82 percent (n = 20); 6.14 percent hypothyroidism; 0.68 percent hyperthyroidism. TPOAb was present in 5.46 percent of euthyroid patients. Out of 273 euthyroid patients at baseline, 19 percent developed TD: 17.2 percent hypothyroidism; 1.8 percent hyperthyroidism; 5.1 percent destructive thyroiditis (DT). 90 percent of TPOAb-positive patients at baseline developed hypothyroidism vs 14.5 percent of TPOAb-negative patients (p < 0.001). On average, TD occurred after 25.8 ± 15.5 weeks of treatment. 87.2 percent of patients who developed hypothyroidism did so during the first therapeutic cycle (p = 0.004; OR = 3.52; 95 percent CI = 1.36-9.65). Patients infected with genotype 1 virus were 2.13 times more likely to develop hypothyroidism (p = 0.036; 95 percent CI = 1.04-4.38). Hypothyroid and DT patients presented higher TSH levels before-treatment than patients who had remained euthyroid (p < 0.001; p = 0.002, respectively). DT patients presented lower qALT (p = 0.012) than euthyroid patients. CONCLUSION: Hypothyroidism was the most frequent TD, especially during the first cycle of α-interferon. Genotype 1 virus was associated with a risk two times higher for developing the illness. There was no need to interrupt or to change HCV treatment. Therefore, approximately 34 percent of TD was transient.

How frequently should a patient taking amiodarone be screened for thyroid dysfunction?

Amiodarone-induced thyroid dysfunction (AITD) is a common complication of amiodarone therapy and its prevalence varies according to iodine intake, subclinical thyroid disorders and the definition of AITD. There is no consensus about the frequency of screening for this condition. We evaluated 121 patients on chronic regular intake of amiodarone (mean intake = 248.5 ± 89 mg; duration of treatment = 5.3 ± 3.9 years, range = 0.57-17 years) and with stable baseline cardiac condition. Those with noAITD were followed up for a median period of 3.2 years (range: 0.6-6.7) and the incidence rate of AITD, defined by clinical and laboratorial findings as proposed by international guidelines, was obtained (62.8 per 1000 patients/year). We applied the Coxproportional hazard model to adjust for potential confounding factors and used sensitivity analysis to identify the best screening time for follow-up. We detected thyroid dysfunction in 59 (48.7%) of the 121 patients, amiodarone-induced hypothyroidism in50 (41.3%) and hyperthyroidism in 9 (7.5%). Compared with patients without AITD, there was no difference regarding dosage or duration of therapy, heart rhythm disorder or baseline cardiac condition. During the follow-up of the 62 patients without AITD at baseline evaluation, 11 developed AITD (interquartile range, IR: 62.8 (95%CI: 31.3-112.3) cases per 1000 patients/year), 9 of them with hypothyroidism - IR: 11.4 (95%CI: 1.38-41.2), and 2 hyperthyroidism - IR: 51.3 (95%CI: 23.4-97.5). Age, gender,dose, and duration of treatment were not significant after adjustment. During the first 6 months of follow-up the incidence rate for AITD was 39.3 (9.2-61.9) cases per 1000 patients/year. These data show that AITD is quite common, and support the need for screening at 6-month intervals, unless clinical follow-up dictates otherwise or further information regarding the prognosis of untreated subclinical AITD is available.

Avaliação das metaloproteinases de matriz -2 e -9 em gatos com desmineralização óssea secundária à tirotoxicose induzida / Evaluation of matrix metalloproteinases -2 and -9 in cats under bone demineralization secondary to induced thyrotoxicosis

Observou-se significativo aumento de atividade das formas ativas das metaloproteinases -2 e -9 em gatos com tirotoxicose induzida e desmineralização óssea. As formas pró e intermediária da metaloproteinase -2 elevaram-se com 14 dias de administração hormonal, porém, posteriormente, houve uma tendência de queda. Observou-se correlação negativa entre a forma ativa das metaloproteinases de matriz -2 e -9 e a densidade mineral óssea da extremidade distal do rádio. Os resultados sugerem aumento da degradação da matriz colágena secundária com a elevação dos hormônios tiroidianos.

Significant increase of activity of active forms of matrix metalloproteinases -2 and -9 in cats under induced thyrotoxicosis and bone demineralization was observed. Pro and intermediated forms of matrix metalloproteinases -2 and -9 increased at 14 days of hormonal treatment, followed by decrease tendency. A negative correlation between active forms of matrix metalloproteinases -2 and -9 and bone mineral density of radius distal extremity was also observed. The results suggest an increase of collagen matrix degradation secondary to high levels of thyroid hormones.

Hiperparatireoidismo em gatos com hipertireoidismo experimental / Hyperparathyroidism in cats with experimental hyperthyroidism

Os efeitos do hipertireoidismo experimental, 150µg/kg/dia/42 dias de levotiroxina sódica, na homeostase do cálcio foram estudados em 14 gatos sem raça definida, com idades entre um e três anos. A cada 14 dias foram colhidas amostras de soro para a determinação da concentração da tiroxina total (T4), tiroxina livre (FT4), paratormônio intacto (PTH), cálcio total e ionizado, fósforo e, além disso, realizaram-se radiografias para a determinação da densidade mineral óssea (DMO). Observou-se aumento das concentrações séricas do PTH a partir do momento inicial (M0), com diferença significativa deste em relação às concentrações obtidas aos 14 (M1), 28 (M2) e 42 (M3) dias. Não houve diferença significativa nas concentrações séricas de cálcio total e fósforo entre todos os momentos. O cálcio ionizado diminui de M0 para M1 e de M1 para M3, com diferença significativa. Os hormônios tireoidianos apresentaram correlação positiva com o PTH e negativa com o cálcio ionizado. A correlação entre DMO e PTH a partir de M2 foi negativa e entre DMO e fósforo foi negativa somente em M2. Não se observou correlação entre DMO e as demais variáveis. Em M1, M2 e M3 foi observada correlação negativa entre o PTH e o cálcio ionizado. Conclui-se que o hipertireoidismo em gatos adultos jovens está associado ao hiperparatireoidismo secundário devido ao aumento do PTH e diminuição do cálcio ionizado. Os efeitos combinados dos hormônios tireoidianos e do PTH contribuíram para a diminuição da DMO.

The effect of experimental hyperthyroidism, 150µg/kg/day/42 days, on calcium homeostasis was studied in 14 mongrel cats aging from one to three-year-old. Total thyroxine (T4), free thyroxine (FT4), parathyroid hormone (PTH), total and ionized calcium, phosphorus, bone mineral density were measured. Serum concentrations of PTH of increased from the initial moment (MO), with significant differences to when measured after 14(M1), 28(M2), and 42(M3) days. However, significant differences on serum concentrations were not observed among the values of M1, M2, and M3. The ionized calcium significantly decreased from M0 to M1 and from M1 to M3. Thyroid hormones showed positive correlation with PTH and negative with ionized calcium. Bone mineral density showed negative correlation with PTH from M2 to M3 and with phosphorus on M2, with no correlation with the other variables. Negative correlation of PTH with ionized calcium was observed on M1, M2, and M3. In conclusion, hyperthyroidism in young adult cats is associated to secondary hyperparathyroidism due to increase of PTH and decrease of ionized calcium. The combined effects of thyroid hormones and PTH contributed to the reduction of bone mineral density.

Model of induction of thyroid dysfunctions in adult female mice

It is described the elaboration of a protocol to induce hyperthyroidism and hypothyroidism in mice by administrating thyroxin and propylthiouracil, respectively, in the drinking water. The drugs were administered to adult female mice of the Swiss strain for 30 days in order to obtain a systemic status of thyroid dysfunction. The induction of hyperthyroidism and hypothyroidism in the animals was confirmed by the histomorphological analysis of the thyroid in the end of the experiment, when the state of gland dysfunction in the animals submitted to the treatment was observed

Descreve-se a elaboração de um novo protocolo de indução ao hipertireoidismo e hipotireoidismo em camundongos, por meio da administração de tiroxina e propiltiouracil, respectivamente, na água de beber. As drogas foram administradas a camundongos fêmeas adultas Swiss por 30 dias para obtenção das disfunções tireoidianas sistêmicas. A indução de hipertireoidismo e hipotireoidismo nos animais foi confirmada pela análise histomorfológica e histomorfométrica da glândula tireoidiana ao final do experimento, quando observou-se o estado de disfunção glandular nos animais submetidos ao tratamento

Effects of long term iodized table salt consumption on serum T3, T4 and TSH in an iodine deficient area of Bangladesh.

The effect of iodized and non-iodized table salt in goiter hyper-endemic area on the thyroid gland and its hormones T3, T4 and Thyroid Stimulating Hormone (TSH) were studied in two hundred subjects from the Center for Nuclear Medicine and Ultrasound, Mymensingh. Iodized and non-iodized salt users were called study and control groups respectively. The mean concentration of T3 were 2.38 nmol/L and 2.22 nmol/L & T4 concentration were 128.67 and 123.72 nmol/L in the study and control group respectively. The mean TSH concentration was 1.52 mIU/L and 1.62 mIU/L in study and control group. The data indicated that continuous and long term use of iodized salt increased both T3, T4 and decreased TSH in such a limit which was not statistically deferent at P< 0.05 level as compared to the control group. There was no significant change in occurrence of (hypo and hyper thyroidism or iodinated salt induced thyrotoxicosis) adverse effect, following iodine supplementation. The study shows that, mandatory mass iodination of table salt consumption in a hyper-endemic iodine deficient area is safe and does not cause any side effect. We suggest close regular monitoring of T3, T4, and TSH and further evaluation by specifically designed studies for any probable link between iodine induced hypo or hyperthyroidism and mass iodination of table salt consumption.

Cardiovascular changes in thyroid disorder.

Thyroid hormones have a profound effect on the metabolism. The cardiovascular system is particularly sensitive to this metabolic alteration. Therefore it is not surprising that thyroid dysfunction can produce dramatic cardiovascular effects, often mimicking primary cardiac disease. Both hypothyroidsm and hyperthyroidsm produce a clinical syndrome causing a diagnostic and therapeutic dilemma to the endocrinologist and cardiologist. Furthermore, cardiac disease and amiodarone therapy can also produce thyroid abnormality.

Amiodarone-induced thyroid dysfunction in a tertiary center in south Brazil

Amiodarone, used in the treatment of cardiac arrhythmias, is associated with thyroid dysfunction. No reports exist on its frequency in southern Brazil, nor studies evaluating the usefulness of clinical scores to diagnose thyroid abnormalities in these patients. This study aimed at determining the prevalence of amiodarone-induced thyroid dysfunction in a representative sample from a tertiary center, to study the conditions associated to this dysfunction and to evaluate the reliability of clinical scores of hypo and hyperthyroidism. One hundred ninety-five amiodarone users were submitted to a clinical and laboratory evaluation. Of these, 2.1 percent were hyperthyroid, 25.1 percent hypothyroid and 9.2 percent had only a high T4. Considering thyroid dysfunction variables researched, thyroid autoimmunity was positively associated (OR 4.8; p= 0.02), and male gender had a trend to a positive association (OR 1.86; p= 0.06). Clinical scores were highly sensitive for hyperthyroidism (100 percent), but not for hypothyroidism (8 percent). The low prevalence of amiodarone-induced hypothyroidism suggests that this specific region is iodine-sufficient. All patients receiving chronic amiodarone therapy should be checked for clinical scores for hyperthyroidism and laboratory evaluation should be performed, as a screening for thyroid dysfunction, especially if they are male or have positive microsomal antibodies.

Histomorfometria dentária de ratas com hipertireoidismo induzido durante ou após a erupção e com hipotireoidismo após a erupção dentária / Dental histomorphometry in rats with hyperthyroidism induced by or after eruption and with hypothyroidism after dental eruption

Foram realizados três experimentos a fim de estudar a histomorfometria dos dentes de ratas com hipertireoidismo induzido durante ou após a erupção dentária e hipotireoidismo induzido após erupção dentária. O hipertireoidismo alterou a morfologia dos dentes molares quando induzido durante a erupção, acelerando o desenvolvimento das raízes dentárias, mas não alterou o dente incisivo de ratas adultas. Os efeitos do hipotireoidismo foram mais significativos nos dentes molares do que nos incisivos. Apesar da hipofunção tireoidiana causar redução da porcentagem de células da polpa dentária e da espessura da camada de odontoblastos, houve aumento da espessura da camada de dentina com formação de dentina reacional e necrose

Changes in lipid peroxidation and free radical scavengers in kidney of hypothyroid and hyperthyroid rats.

Kidney weight was significantly decreased in hypothyroidism (induced by Na131I administration) and increased in hyperthyroidism (induced by thyroxine treatment) as compared to control in female Wistar rats. The tissue lipid peroxidation level remained unchanged in hyperthyroid rats but significantly increased in hypothyroid rats. Superoxide dismutase was decreased in both experimental groups but more so in hyperthyroid rats. Catalase was reduced significantly in hyperthyroid rats but remained unaffected in hypothyroid rats. Tissue glutathione peroxidase (GPx) activity was increased while reduced glutathione levels remained unaltered in both hypothyroid and hyperthyroid rats. Plasma GPx activity was significantly low in both the hypothyroid and hyperthyroid rats. The results suggest alterations in the oxidative stress in hypothyroid and hyperthyroid rat kidneys with concomitant changes of free radical scavengers.

Foliculogênese esteroidogênese ovarianas em ratas adultas hipertireóideas / Ovarian folliculogenesis and steroidogenesis in hyperthyreiods adult rats

A foliculogênese e a esteroidogênese ovarianas foram estudadas em ratas adultas hipertireóideas. O hipertireoidismo foi induzido em 27 ratas Wistar com cinco meses de idade pela administração diária de 50ng de L-tiroxina. Outras 27 ratas foram mantidas em estado eutireóideo e serviram como controle. Aos 30, 60 e 90 dias após o início do tratamento, nove ratas de cada grupo foram sacrificadas, os ovários inspecionados, pesados e processados para avaliação histomorfométrica e o plasma sanguíneo colhido para dosagem de T4-livre, estradiol e progesterona. As concentrações plasmáticas de T4-livre foram significativamente maiores nas ratas hipertireóideas aos 30, 60 e 90 dias, e o peso médio dos ovários foi significativamente maior somente aos 90 dias. Já o número de folículos secundários e terciários e de corpos lúteos foi significativamente maior aos 60 ou aos 90 dias, mas a taxa percentual de atresia folicular só foi diferente aos 90 dias. O número de folículos primários e pré-ovulatórios, assim como as concentrações plasmáticas , de estradiol e progesterona, não diferiram entre grupos e entre períodos. Concluiu-se que o hipertireoidismo estimula a foliculogênese ovariana em ratas sexualmente maduras e diminui a atresia folicular.

Evaluation of the activity of receptor-operated Ca2+ channels in rat portal vein in induced hyperthyroidism.

The activity of receptor-operated Ca2+ channels (ROCCs) was studied in rat portal vein in L-thyroxine-induced experimental hyperthyroidism. The following parameters were evaluated: 1. NE-stimulated 45Ca influx. 2. CaCl2-induced contractile responses in Ca2+ free NE-stimulated tissues to calculate EC50 value of CaCl2. The NE (10(-6)mol) stimulated 45Ca influx and the mean EC50 value of CaCl2 did not differ significantly in portal veins isolated from hyperthyroid rats as compared to those of euthyroid control rats. The study revealed no significant change in the functional status of ROCCs in experimental hyperthyroidism.

Alteraciones ultraestructurales del hepatocito de ratas hipertiroideas alimentadas con uan dieta suplementada con ácidos grasos poli-insaturados de la serie n-3 / Ultrastructural hepatocyte alterations in hypertiroid rats fed with a diet enriched with poly-nonsaturated fatty acids n-3

Tanto el hipertiroidismo experimental como la administración de una dieta rica en aceite de pescado, alteran la ultraestructura mitocondrial del hepatocito. Los cambios observados utiizando microscopía electrónica de transmisión fueron específicos para el tratamiento con la hormona como para la administración de la dieta. Sin embargo, cuando ambos procedimientos se emplearon simultáneamente, las mitocondrias mostraron una estructura similar a aquella de los animales alimentados con el aceite de pescado (ácidos grasos poliinsaturados n-3). Los peroxisomas muestran alteraciones del nucleoide y se encuentran asociados a mitocondrias, reflejando la interacción que existe entre estas organelas en el proceso de B-oxidación de los ácidos grasos de cadena larga. Los cambios esturcturales observados pueden deberse a modificaicones en la composición de ácidos grasos de las membranas de estas estructuras producidos por ambos tratamientos. Los cambios ultraestructurales pueden explicar variaciones en la función de las estructuras alteradas

Interaction of calcium channel blockers (CCBs) with histamine and 5-hydroxytryptamine in aorta from normal and diseased rats.

The present study attempts to investigate the interaction of calcium channel blockers (CCBs) with histamine (H) and 5-hydroxytryptamine (5-HT) in rat isolated aortic strip preparations. In preparations obtained from rats chronically treated with various CCBs the contractile responses to H were completely blocked suggesting that this may be due to inhibition of the voltage-dependent channels and inositol 1,4,5-triphosphate induced release of calcium from intracellular stores. The decreased contractions of the aortic strip preparations with 5-HT obtained from rats chronically treated with various CCBs implies a decrease in 5-HT receptor density. DOCA-saline hypertensive rats chronically treated with various CCBs showed variable responses to H and 5-HT suggesting that these changes may be due to different isoforms of L-type calcium channels. In L-thyroxine-treated preparations or those simultaneously treated with L-thyroxine and CCBs the responses to H were abolished and those to 5-HT were partially blocked with decrease in maxima which could be secondary to the primary effect on the heart and to generalised reduced senstivity of the rat aorta.

Hipertiroidismo secundario a amiodarona: presentación de un caso / Amiodarone as a cause of hyperthyroidism

El hipertiroidismo secundario al uso de amiodarona es una condición rara, y en la mayoría de los casos resistente al tratamiento farmacológico convencional, por esta razón se considera la cirugía como la mejor alternativa terapéutica. Se presenta el caso de un paciente de 63 años, con bocio intramediastínico voluminoso asociado a signos y síntomas de hipertiroidismo, confirmado bioquímicamente. El bocio había sido descubierto 10 años antes, incidentalmente en un estudio radiológico de tórax. En los últimos seis meses había tomado amiodarona por episodios de taquiarritmia. El centellograma con yodo radioactivo mostro un bloqueo glandular y una presa muy pobre del radiofármaco. Con diagnóstico de hipertiroidismo secundario al uso de amiodarona el paciente fue operado ycurado. Se discute la fisiopatología de la enfermedad, así como las justificaciones y los resultados del tratamiento quirúrgico

Histological and histochemical studies on the effect of experimentally induced hypothyroidism by carbimazole on the kidney of the female albino rat

The present investigation comprised the study of the effect of experimentally induced hypothyroidism on the kidney of the female albino rats, with an average weight 200 g. Experimentally induced hypothyroidism was performed by giving 12 animals a daily oral dose of 2.4 mg carbimazole for 3 and 4 months, respectively. 6 age-matched animals were used as controls. The kidneys of the experimentally induced hypothyroid animals presented a significant decrease in the mean value of their weights, as well as marked histological changes in the renal corpuscles, proximal convoluted tubules, and the interstitial tissue of the kidney. These changes were more marked in animals with an experimentally induced hypothyroidism for 4 months. The histochemical changes in the kidney were more marked in animals with an experimentally induced hypothyroidism for 4 months. The succinic dehydrogenase enzyme activity was markedly increased in the lining cells of most of the proximal convoluted tubules. Moreover, the alkaline phosphatase enzyme activity was increased in the lining cells of most of the proximal convoluted tubules, especially those in the inner cortical region. Some proximal convoluted tubules in the outer cortical region showed a decreased alkaline phosphatase enzyme activity in their lining cells