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Increased expression of thyroid hormone receptor isoforms in end-stage human congestive heart failure.

Thyroid hormone plays an important role on myocardial development and function. The local effects of thyroid hormone are mediated by the receptor isoforms ultimately driving the expression of cardiac-specific genes. Although overt and subclinical thyroid dysfunction causes well-known changes in the cardiovascular system, little is known about local thyroid hormone action in normal and failing human myocardium. With a newly developed multiplex competitive RT-PCR method, we evaluated the expression of thyroid hormone receptor (TR) isoforms alpha-1, alpha-2, and beta-1 in normal human hearts and in end-stage congestive heart failure. A statistically significant difference in the expression of all three TR isoforms was observed among samples from normal subjects, ischemic heart disease (IHD), and dilated cardiomyopathy (DCM). In DCM, compared with normal, the studied TR isoforms were significantly increased. In IHD, the increased expression was found significant only for alpha-1 and alpha-2 isoforms. No differences were observed between the pathologic groups. In conclusion, a coordinated increment in the expression of the TR isoforms was observed in both DCM and IHD by multiplex competitive RT-PCR. The observed changes could represent a compensatory mechanism to myocardial failure or to locally altered thyroid hormone action.

Adult↗

Influence of lithium on growth and viability of thyroid follicular cells.

Lithium accumulates in the thyroid gland and can cause goiter or thyroid dysfunction. The aims of our work were: 1) to verify whether lithium stimulates proliferation of thyroid cells; as methods, the 3H-thymidine incorporation assay and the MTT assay (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) were used; as a model system the FRTL-5 (Fischer rat thyroid cells in low serum) cell line was selected, 2) to test whether lithium can have a cytotoxic effect on FRTL-5 cells, using the cytotoxicity assay with 51Cr release and the trypan blue exclusion method. Without TSH stimulation, lithium at 0.35-2 mM concentrations significantly increased the 3H-thymidine incorporation. A similar effect was observed in the case of the MTT assay: without TSH stimulation, lithium at 0.4-2 mM concentrations showed a significant stimulation of proliferation. Surprisingly, under TSH stimulation, lithium at the 2 mM concentration significantly inhibited proliferation of FRTL-5 cells. With the cytotoxicity assay, lithium was found to increase 51Cr release at 1.4-2 mM concentrations. Additionaly, the percentage of viable FRTL-5 cells at 0.35-2 mM concentrations of lithium was lower than in the controls without lithium. In conclusion, lithium was found to stimulate proliferation of FRTL-5 cells in conditions without TSH and, surprisingly, lithium in higher concentrations diminished proliferation of FRTL-5 cells under TSH stimulation. A cytotoxic effect of higher lithium concentrations was observed.

Animals↗

Pregnancy and autoimmune thyroid disease.

Pregnancy has profound effects on the course of Graves' disease and Hashimoto's thyroiditis. Understanding of this interrelationship may clarify the role of the numerous immunologic gestational alterations that facilitate survival of the fetal allograft. Also, it should provide a more rational basis in the management of Graves' hyperthyroidism during pregnancy. Epidemiologic data indicate that screening for thyroid dysfunction appears justified in women in the postpartum period. The natural history of the postpartum thyroiditis syndrome remains to be fully evaluated, but the evidence indicates thyroid abnormalities can still be found in many patients several years after onset. Accordingly, the importance of follow-up cannot be overemphasized.

Female↗

Papillary carcinoma of the thyroid after postpartum thyroiditis.

Postpartum thyroiditis is a benign, often self-limited cause of thyroid dysfunction. This report describes the first case of papillary carcinoma arising in a woman with postpartum thyroid disease. Both clinicians and pathologists must keep a high index of suspicion in postpartum patients with persistent thyroid abnormalities, even when a previous biopsy may have disclosed benign disease.

Adult↗

Post-partum thyroiditis in South Brazil presenting as thyrotoxicosis: prevalence and risk factors.

The prevalence of post-partum thyroiditis (PPT) has been reported in several countries (1.9 to 16.7%) but is not known in Brazil. Several factors have been associated to its development, such as a female sex of the newborn, PPT in a previous pregnancy, a family history of thyroid disease and cigarette smoking. To investigate the prevalence of PPT and its risk factors in a southern Brazilian city, a three-cross-sectional observation study was performed. PPT was diagnosed in 14/284 subjects (5.3%) and all cases had thyrotoxicosis (13 sub-clinical and one clinical). Serum total T4 and free T4 were higher and serum TSH was lower in PPT subjects. Anti-thyroid antibodies were positive in 16.7% of PPT subjects and in 4.5% of those with no thyroid dysfunction. Goiter was identified in 14.3% of PPT subjects and in 15% of no PPT subjects. Thyroid was hardened more frequently in PPT subjects (21.4%) than in others (5.2%). Male sex of the newborn was associated to PPT, increasing 11 times the risk of PPT. Cigarette smoking was associated to PPT in group II subjects. There was no clinical sign or symptom able to contribute to this diagnosis, except the presence of hardened thyroid. Based on these findings, PPT, manifesting itself as mild thyrotoxicosis, is a common problem in southern Brazil and is associated to male sex of the newborn.

Adult↗

Developmental delays associated with prenatal alcohol exposure are reversed by thyroid hormone treatment.

Exposure to alcohol in utero has been associated with hypothyroidism and a variety of developmental defects characteristic of thyroid dysfunction. The present work examined whether these abnormalities could be reversed in infant rats treated with thyroid hormones. Subjects were offspring of dams which were on the following diet regimen during gestation: (1) free access to liquid diet containing ethanol (alcohol pups); (2) an equal volume of isocaloric liquid diet (pair-fed pups); or (3) ad libitum control diet (control pups). Neonates from each group were foster-nursed by control dams, and received triiodothyronine (T3; 0.1 mg/kg/day; s.c.) or saline treatments on postnatal days 1 to 10. The alcohol neonates displayed reduced serum thyroxine which was restored to normal by postnatal day 14. In addition, these pups showed a delayed appearance of developmental landmarks, including righting reflex, dental eruption, auditory startle response and eye opening. The retarded incisor eruption and eye opening were reversed in alcohol pups by T3 treatments. The present data suggest that at least some of the developmental abnormalities associated with prenatal alcohol exposure are attributable to perinatal hypothyroidism and can be restored by early hormone replacement therapy.

Abnormalities, Drug-Induced↗

Hypothyroidism in Down's syndrome.

Fifty-five adult Down's syndrome subjects resident at Northgate Hospital were screened for the presence of thyroid dysfunction. Approximately 50% of the subjects had clinical features suggestive of hypothyroidism, sufficient to require thyroid-function tests. Twenty-two per cent of the total suffered from some degree of hypothyroidism, and 16% had positive antibodies to thyroid tissue.

Adult↗

Postpartum thyroiditis and autoimmune thyroiditis in women of childbearing age: recent insights and consequences for antenatal and postnatal care.

Postpartum thyroiditis is a syndrome of transient or permanent thyroid dysfunction occurring in the first year after delivery and based on an autoimmune inflammation of the thyroid. The prevalence ranges from 5-7%. We discuss the role of antibodies (especially thyroid peroxidase antibodies), complement, activated T cells, and apoptosis in the outbreak of postpartum thyroiditis. Postpartum thyroiditis is conceptualized as an acute phase of autoimmune thyroid destruction in the context of an existing and ongoing process of thyroid autosensitization. From pregnancy an enhanced state of immune tolerance ensues. A rebound reaction to this pregnancy-associated immune suppression after delivery explains the aggravation of autoimmune syndromes in the puerperal period, e.g., the occurrence of clinically overt postpartum thyroiditis. Low thyroid reserve due to autoimmune thyroiditis is increasingly recognized as a serious health problem. 1) Thyroid autoimmunity increases the probability of spontaneous fetal loss. 2) Thyroid failure due to autoimmune thyroiditis-often mild and subclinical-can lead to permanent and significant impairment in neuropsychological performance of the offspring. 3) Evidence is emerging that as women age subclinical hypothyroidism-as a sequel of postpartum thyroiditis-predisposes them to cardiovascular disease. Hence, postpartum thyroiditis is no longer considered a mild and transient disorder. Screening is considered.

Adult↗

Small differences in thyroid function may be important for body mass index and the occurrence of obesity in the population.

CONTEXT: Increasing prevalence of overweight in the population is a major concern globally; and in the United States, nearly one third of adults were classified as obese at the end of the 20th century. Few data have been presented regarding an association between variations in thyroid function seen in the general population and body weight. OBJECTIVE: The aim of this study was to investigate the association between thyroid function and body mass index (BMI) or obesity in a normal population. DESIGN: A cross-sectional population study (The DanThyr Study) was conducted. PARTICIPANTS: In all, 4649 participants were investigated, and 4082 were eligible for these analyses after exclusion of subjects with previous or present overt thyroid dysfunction. MAIN OUTCOME MEASURES: The study examined the association between category of serum TSH or serum thyroid hormones and BMI or obesity in multivariate models, adjusting for possible confounding. RESULTS: We found a positive association between BMI and category of serum TSH (P < 0.001) and a negative association between BMI and category of serum free T(4) (P < 0.001). No association was found between BMI and serum free T(3) levels. The difference in BMI between the groups with the highest and lowest serum TSH levels was 1.9 kg/m(2), corresponding to a difference in body weight of 5.5 kg among women. Similarly, the category of serum TSH correlated positively with weight gain during 5 yr (P = 0.04), but no statistically significant association was found with weight gain during 6 months (P = 0.17). There was an association between obesity (BMI > 30 kg/m(2)) and serum TSH levels (P = 0.001). CONCLUSIONS: Our results suggest that thyroid function (also within the normal range) could be one of several factors acting in concert to determine body weight in a population. Even slightly elevated serum TSH levels are associated with an increase in the occurrence of obesity.

Adolescent↗

Relationship between breast cancer and thyroid disease: relevance of autoimmune thyroid disorders in breast malignancy.

The relationship between thyroid dysfunction and breast cancer (BC) is debated. To clarify this controversial issue, a prospective study on thyroid function in BC was performed. The prevalence of thyroid disease was examined in 102 consecutive BC patients with ductal infiltrating carcinoma after surgery and before starting any chemohormonal or x-ray therapy and in 100 age-matched control healthy women living in the same borderline iodine-sufficient geographic area. All subjects were submitted to clinical ultrasound thyroid evaluation and serum free T4, free T3, TSH, thyroperoxidase antibody, and thyroglobulin antibody determination. Fine needle aspiration was performed in all thyroid nodules. Estrogen and progesterone receptors (ER and PR, respectively) were assayed in 92 and 55 BC specimens, respectively. The overall prevalence of thyroid disease was 47 in 102 (46%) in BC patients and 14 in 100 (14%) in controls (P < 0.0001). The prevalence of nontoxic goiter was 27.4% in BC patients and 11% in controls (P = 0.003). Hashimoto's thyroiditis was found in 13.7% of BC patients and in only 2% of the controls (P < 0.005). Other thyroid disorders found in the BC group included 2 cases of Graves' disease, 2 of thyroid carcinoma, and 1 of subacute thyroiditis, whereas in the control group only 1 case of Graves' disease and none of the other disorders were found. Mean free T3, free T4, and TSH concentrations showed no difference between BC patients and controls. The prevalence of thyroperoxidase antibody was higher in BC patients than in controls (23.5% vs. 8%; P < 0.005), whereas the prevalence of thyroglobulin antibody was not different. In BC patients the presence of thyroid antibodies was more frequently associated with clinically detectable autoimmune thyroiditis (14 of 26, 51.8%; P = 0.03) and was more common in the younger group. The positivity of ER was found in 51 of 92 (55.43%) and that of PR was found in 26 of 55 (47.27%) BC specimens. No relationship was found among ER, PR status, and the presence of serum thyroid antibodies. In conclusion, 1) the present study provides evidence that the overall prevalence of thyroid disorders is increased in patients with breast cancer, and 2) thyroid autoimmune disorders, especially Hashimoto's thyroiditis, account to a large extent for the increased prevalence of thyroid disease in patients with breast cancer. This feature is independent from the ER and PR status of the primary tumor. The present findings call attention to the usefulness of screening for thyroid disease in any patient with breast cancer.

Adult↗

Influence of cigarette smoking on thyroid function, goiter formation and autoimmune thyroid disorders.

Both smoking and thyroid dysfunction are frequent in the general population. Many studies have shown that cigarette smoking interferes with thyroid function and with the evolution of thyroid pathology (e.g. goiter formation and thyroid cancer development). Some studies have also suggested a significant correlation of Graves' hyperthyroidism and Graves' ophthalmopathy with the severity of smoking. In addition, cigarette smoking may reduce the effectiveness of some therapeutic modalities, such as orbital radiotherapy or high-dose systemic glucocorticoid administration for severe thyroid eye disease. Tobacco smoking seems to induce similar changes in thyroid function in the adult and the fetus. This review article discusses the effect of cigarette smoking on thyroid function and morphology as well as on thyroid autoimmunity.

Journal Article↗

Autoimmune manifestations during interferon therapy in patients with chronic hepatitis C: the hepatologist's view.

In face of numerous benefits induced by therapy based on interferon (IFN) associated with ribavirin for the treatment of chronic hepatitis C, there is an increasing concern regarding its tolerance, which can, in some cases, reduce the quality of life as well as compliance of patients. Among the less common side effects, there are the autoimmune ones which can be globally divided into appearance or increase in titres of auto-antibodies and/or manifestation of overt autoimmune pathologies. Whereas the former may concern more than 50% of treated subjects, the latter is reported in only 1-2% of patients under therapy. Thyroid dysfunction represents the well-studied autoimmune disorder. The presence of pre-existing anti-thyroid antibodies and being of female sex, constitute relevant risk factors for the development of a disease involving this gland. Often the treatment of thyropathy must be continuous in spite of IFN discontinuation because the disturbance usually does not abate with stopping antiviral therapy. Some observations have pointed out to the fact that IFN can lead to the development of insulin-dependent diabetes mellitus. Sometimes, during, as well as after IFN treatment, the appearance of anti-islet cell antibodies has been shown, but its interrelationship with the development of disease is uncertain. While being treated with IFN for chronic hepatitis C, the finding of non-organ specific antibodies at baseline can increase the likelihood of the development of autoimmune hepatitis. However, their presence does not constitute an absolute contraindication to the treatment, except in case of high titre. Other disorders, such as a lupus erythematosus-like syndrome, haemolytic anaemia, and immune-mediated thrombocytopenia have been reported. In conclusion, although the presence of auto-antibodies is considered to be an epiphenomenon without pathogenic significance in most patients suffering from chronic hepatitis C, it poses a problem when they need to be treated with IFN. This antiviral drug can induce or exacerbate a multitude of autoimmune-related disorders, however, clinically overt immune-mediated diseases are rare and affect a subset of subjects who have an underlying autoimmune diathesis.

Antiviral Agents↗

Cerebral accumulation of Tc-99m ethyl cysteinate dimer (ECD) in severe, transient hypothyroidism.

Thyroid dysfunction is a well-known contributor to psychiatric morbidity. To investigate the mechanism(s) by which thyroid hormone availability affects cerebral activity, a group of thyroidectomized individuals were studied at two points in time: when markedly hypothyroid in preparation for a thyroid cancer metastatic survey and when clinically and/or biochemically euthyroid. The analysis consisted of single photon emission computed tomography (SPECT) using a lipophilic radiopharmaceutical, technetium-99m (Tc-99m) ethyl cysteinate dimer (ECD), and measurement of mood, anxiety, and psychomotor function, at both points in time. Both increases and decreases in regional cerebral radiotracer activity were found in the hypothyroid condition relative to the euthyroid condition, and the neuropsychological assessment demonstrated significantly greater depression, anxiety, and psychomotor slowing during the hypothyroid state. Increased radiotracer activity was seen in frontal and temporal regions, posterior cingulate gyrus, thalamus, and putamen. Decreased activity was seen in the occipital cortex, and the pre- and postcentral gyri. This distribution pattern is partially consistent with findings in persons with depression and anxiety unrelated to thyroid disease, supporting the link between the symptoms observed in our subjects and their marked hypothyroidism. Finally, these results support the need to consider the effect of the thyroid state on cellular mechanisms of uptake and retention of cerebral blood flow radiopharmaceuticals when studying 'noneuthyroid' individuals.

Adult↗

Rarity of encephalopathy associated with autoimmune thyroiditis: a case series from Mayo Clinic from 1950 to 1996.

Corticosteroid-responsive encephalopathy associated with autoimmune thyroiditis (also called Hashimoto's encephalopathy) is a rare, life-threatening, treatable, and possibly autoimmune condition. We identified nine patients (with the diagnosis made after 1979) who had relapsing encephalopathy compatible with previous reports of Hashimoto's encephalopathy and no other identifiable cause of encephalopathy at Mayo Clinic Rochester. Of these nine patients, three were clinically hypothyroid, four were subclinically hypothyroid, and two were euthyroid. Thyroid antibodies were positive in eight of eight patients in whom these measurements were made. Electroencephalographic abnormalities were identified in eight of the nine patients (89%). Magnetic resonance imaging (MRI) abnormalities considered etiologically related to encephalopathy were present in three patients (33%). An increased protein concentration was noted on cerebrospinal fluid examination in seven patients (78%). Of the six patients who received high-dose glucocorticoid therapy, 5 (83%) had improvement of neurologic symptoms. In conclusion, encephalopathy associated with autoimmune thyroiditis is rare but important to recognize because it may be responsive to high-dose glucocorticoid therapy. We believe that this condition is not caused by thyroid dysfunction or antithyroid antibodies but represents an association of an uncommon autoimmune encephalopathy with a common autoimmune thyroid disease. The term Hashimoto's encephalopathy is a misnomer and should not be used.

Adolescent↗

French approach for the distribution of iodine tablets in the vicinity of nuclear power plants.

In the event of an accident, isotopes of iodine including 131I can be released into the atmosphere. In 1997, as a safety measure, the French government decided to begin the distribution of stable iodine tablets in advance, directly to those living in the vicinity of the nuclear power plants, to avoid having to do so in an emergency. The tablets were previously stored by Electricite de France (EDF), which held them at the disposal of the government authorities. This year, as the existing tablets pass their use--by date, EDF has begun redistributing stable iodine within a ten-kilometer radius around its nineteen nuclear sites. We review the effectiveness of this countermeasure as well as the nature and incidence of possible side effects while measuring the duration of its action under the conditions in which it was administered. A bibliographic study of the kinetics of iodine in the human body has enabled the indications and the means of use to be determined. The effectiveness of the preventive effect and the onset of thyroid dysfunction depends on both external and individual factors: uptake of iodine from food, functional condition of the thyroid, and age. In an individual with a healthy thyroid, taking 100 mg of stable iodine immediately before exposure to radioactive iodine reduces the dose to the thyroid by at least 95%. In cases of prolonged exposure, the reduction is smaller. Therefore, if exposure lasts for a number of days, consideration needs to be given to taking stable iodine again, to maintain maximum protection. In addition to the bibliographic study, this presentation covers the impact of making iodine available and the action taken to educate the public; the attitudes of populations concerned; and the reaction of the health professionals.

France↗

Fast fluorometric method for measuring pendrin (SLC26A4) Cl-/I- transport activity.

Malfunction of the SLC26A4 protein leads to Pendred syndrome, characterized by sensorineural hearing loss, often associated with mild thyroid dysfunction and goiter. It is generally assumed that SLC26A4 acts as a chloride/anion exchanger, which in the thyroid gland transports iodide, and in the inner ear contributes to the conditioning of the endolymphatic fluid. Here we describe a fast fluorometric method able to be used to functionally scrutinize SLC26A4 and its mutants described in Pendred syndrome. The validation of the method was done by functionally characterizing the chloride/iodide transport of SLC26A4, and a mutant, i.e. SLC26A4(S28R), which we previously described in a patient with sensorineural hearing loss, hypothyroidism and goiter. Using the fluorometric method we describe here we can continuously monitor and quantify the iodide or chloride amounts transported by the cells, and we found that the transport capability of the SLC26A4(S28R) mutant protein is markedly reduced if compared to wild-type SLC26A4.

Biological Transport↗

Bioelectrical impedance assessment of body composition in thyroid disease.

To assess the metabolic effects of thyroid disease, body composition was determined by bioimpedance analysis (BIA) in 72 patients with untreated hyperthyroidism (mean age 48.7 +/- 1.9 years) and 26 patients with untreated hypothyroidism (63.8 +/- 3.4 years). Bioelectrical whole body resistance (R) and reactance (Xc) were used for computerized calculation of lean body mass (LBM), body cell mass (BCM), extracellular mass (ECM) and body fat (BF). Compared with age- and sex-matched healthy controls the most sensitive parameter indicating excess thyroid hormone was the ECM/BCM ratio which was markedly elevated in all hyperthyroid subjects. ECM/BCM alteration resulted from marked depletion of BCM with concomitant expansion of ECM. BCM change is thought to be predominantly due to a loss of muscle mass while ECM rise may reflect an increase in extracellular fluids. In contrast, hypothyroidism was characterized by an increase in BF besides a relatively unaffected LBM component. Serum parameters of thyroid function (tri-iodothyronine (T3), free thyroxine, TSH) did not correlate with the determinants of body composition except for a slight inverse relationship between the phase angle (Xc/Rx180 degrees/pi) and T3 concentration in Graves' disease patients. We conclude that hyperthyroidism is primarily accompanied by quantitative as well as qualitative changes in the lean body while considerable fat increase is the most important feature of hypothyroidism. Severity of body composition derangement cannot be predicted from the degree of thyroid dysfunction. BIA could become a useful tool which allows objective determination of even subtle metabolic manifestations of thyroid disease and should, therefore, complement conventional clinical and biochemical assessment.

Body Composition↗

Thyroid hormone levels in patients with aortic dissection: comparison with controls and correlation with the percentage of the aortic media composed of myxoid deposits.

OBJECTIVE: Deposits of myxoid material, similar to myxedema related to thyroid disease, are described in the medial layer of aortas with dissection. We analyzed the clinical or subclinical thyroid dysfunction of patients with this disease and analyzed whether a correlation exists between serum levels of thyroid-related hormones and the myxoid content of the aortic media. METHODS: We measured, with standard methods, serum levels of triiodothyronine (T3), thyroxine (T4), and thyroid stimulating hormone (TSH) in 28 patients who underwent aortic dissection and free T4 in 20 of them. The same hormones were quantified in 20 control patients matched by sex and age. Results were compared by using the Mann-Whitney test. We also measured the percentage of the aortic media occupied by myxoid material in the surgical specimens of 25 of the patients with aortic dissection and analyzed its correlation with hormone levels by using the Pearson test. RESULTS: In the 20 pairs in which the amount of hormones was compared, the mean values for T3, T4, free T4, and TSH were 1.22ng/mL, 9.89mcg/dL, 1.18ng/dL, and 5.45 microIU/mL in study patients and 1.15ng/mL, 8.57mcg/dL, 1.32ng/dL, and 2.15 microIU/mL in controls. Neither these differences nor the correlation between the percentage of myxoid content (mean=30%) and the values for T3, T4, free T4, and TSH (mean 1.22ng/mL, 9.44mcg/dL, 1.20ng/dL, and 5.08 microIU/mL, respectively; n= 25) were significant. CONCLUSION: Our data suggest that serum levels of thyroid hormones have no relation with the myxoid content in the aortic media in cases of aortic dissection.

Adult↗