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PubMed1976

Influence of neonatal and adult hyperthyroidism on behavior and biosynthetic capacity for norepinephrine, dopamine and 5-hydroxytryptamine in rat brain.

In neonatal rats, administration of l-triiodothyronine (10 mug/100 g/day) for 30 days presented signs of hyperthyroidism which included accelerated development of a variety of physical and behavioral characteristics accompanying maturation. The spontaneous motor activity was increased by 69%. Exposure of developing rats to thyroid hormone significantly increased the endogenous concentration of striatal tyrosine and the activity of tyrosine hydroxylase as well as the levels of dopamine in several brain regions. The concentration of striatal homovanillic acid and 3,4-dihydroxyphenylacetic acid, the chief metabolites of dopamine, was also increased and the magnitude of change was greater than the rise in dopamine. Despite increases in the activity of tyrosine hydroxylase and the availability of the substrate tyrosine, the steady-state levels of norepinephrine remained unaltered in various regions of brain except in cerebellum. Futhermore, neonatal hyperthyroidism significantly increased the levels of midbrain tryptophan and tryptophan hydroxylase activity but produced no change in 5-hydroxytryptamine levels of several discrete brain regions, except hypothalamus and cerebellum where its concentration was slightly decreased. However, the 5-hydroxyindoleacetic acid levels were enhanced in hypothalamus, ponsmedulla, midbrain, striatum and hippocampus. The elevated levels of 5-hydroxyindoleacetic acid did not seem to be due to increased intraneuronal deamination of 5-hydroxytryptamine since monoamine oxidase activity was not affected in cerebral cortex and midbrain of hyperthyroid rats. The data demonstrate that hyperthyroidism significantly increased the synthesis as well as the utilization of catecholamines and 5-hydroxytryptamine in maturing brain. Since the mature brain is known to respond differently to thyroid hormone action than does the developing brain, the effect of L-triiodothyronine treatment on various putative neurohumors also was examined in adult rats. Whereas administration of l-triiodothyronine (10 mug/100 g/day) for 30 days to 120-day-old rats increased the levels of tyrosine by 23% and of tryptophan by 43%, no appreciable change was noted in tryptophan hydroxylase activity. In contrast to neonatal hyperthyroidism, excess of thyroid hormone in adult rats failed to produce any change in motor activity and tended to decrease striatal tyrosine hydroxylase activity only slightly. The concentration of dopamine remained unchanged in all regions of the brain except in midbrain where it rose by 19%. Whereas norepinephrine concentration was altered in hypothalamus, pons-medulla and midbrain, the levels of 5-hydroxytryptamine and its metabolite, 5-hydroxyindoleacetic acid, were significantly decreased in striatum and cerebellum. Since dopaminergic and noradrenergic neurons are the critical components of the motor system, the possibility exists that elevated behavioral activity in young L-triiodothyronine-treated animals might be associated with increased turnover of catecholamines in neuronal tissue.

Animals↗
PubMed1986

Thyroid-stimulating antibodies in patients with long-term remission of Graves' hyperthyroidism.

The persistence of TSH receptor antibodies in Graves' disease despite the remission of hyperthyroidism has been described. Our study was designed to evaluate whether this extends to functionally active stimulators of the thyroid, since the occurrence of thyroid-stimulating antibodies (TSAb) in a euthyroid patient could well have important implications on our understanding of the pathogenetic role of such autoantibodies. Forty-four patients with a previous history of Graves' hyperthyroidism were reexamined after having been in long-lasting remission for 3 to 35 years (mean 8 years). Of the patients 16 had been treated by radioiodine, 17 by surgery, and 11 exclusively by antithyroid drugs. The determination of TSAb was based on T3 release from thyroid tissue in vitro to document the final response to these immunoglobulins. TSH-binding inhibiting immunoglobulins (TBII) were evaluated by a radioreceptor assay. TSAb were highly elevated in three of the 44 patients. These three patients showed a normal TSH response to i.v. TRH, suffered from endocrine ophthalmopathy, and had been treated by radioiodine for hyperthyroidism. TBII were found positive in seven patients including the three patients mentioned. The majority of patients positive for TSAb or TBII had been treated by radioiodine and none exclusively by antithyroid drugs. In conclusion, not only TBII but also T3 release-stimulating antibodies may occur in a minority of patients with long-term remission of Graves' hyperthyroidism. However, an absence of hyperthyroidism in these patients despite the presence of such thyroid stimulators seems to be only possible in association with a lack of functional responsiveness of the target organ due to previous administration of destructive therapies.(ABSTRACT TRUNCATED AT 250 WORDS)

Follow-Up Studies↗
PubMed1998

Hyperthyroidism influences ultrasound bone measurement on the Os calcis.

The objective of our study was to compare bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DXA) and quantitative ultrasound (QUS) parameters in women with hyperthyroidism and controls. In this cross-sectional study, QUS parameters and BMD values observed in untreated hyperthyroid patients were compared with data obtained from age-matched controls. Twenty-four women with Graves' disease were studied. Eight patients were postmenopausal. All patients had evidence of thyrotoxicosis as indicated by a raised total serum thyroxine and a suppressed serum thyroid stimulating hormone. BMD of the hip, lumbar spine and whole body, and body composition, were measured by DXA. Ultrasound evaluation on the os calcis was performed with an Achilles device. All measurements were performed before antithyroid therapy. The QUS parameters of BUA, SOS and Stiffness were significantly lower in hyperthyroid patients than in controls. Similar results were observed for the BMD of lumbar spine, femoral neck and total skeleton. Lean tissue and fat mass were also significantly decreased in hyperthyroid patients. In conclusion, these findings suggest that hyperthyroidism affects cortical and trabecular bone equally, as well as bone quality. QUS measurements may be helpful for assessing, using a simple and non-irradiating method, the bone effects of thyrotoxicosis.

Absorptiometry, Photon↗
PubMedDate not supplied

Altered laboratory thyroid parameters indicating hyperthyroidism in elderly subjects.

The most common laboratory alterations of thyroid function indicating hyperthyroidism were evaluated in a series of 3015 subjects over 65 years of age by determining total T3, total T4 and TSH. Ultrasound and scintigraphy of the thyroid were performed where necessary. Our results showed a high prevalence of laboratory alterations hyperthyroidism type of around 8.09%, whereas the real prevalence (both clinical and laboratory) is 2.00% with a female/male ratio of 2.00. The most frequent hyperfunctioning thyreopaty is thyroidal adenoma (50%), followed by toxic multinodular goiter (33%) and Basedow's disease (17%). The most common clinical signs of hyperthyroidism involve the neuromuscular system and are often present in the so called 'euthyroid' elderly subject. We conclude that it is very difficult to diagnose hyperthyroidism in the elderly on clinical and laboratory grounds. The most significative laboratory thyroid parameter indicating hyperthyroidism seems to be TSH values below 0.2 IU/ml determined using the ultrasensitive IRMA method.

Journal Article↗
PubMed2004

Elevated urinary 8-isoprostaglandin F(2alpha) in females with Graves' hyperthyroidism.

In this study, we investigate how oxidative stress alters the urinary F2-isoprostanes' level and we examine the correlation between 8-isoPGF(2alpha) and thyroid hormones in female patients with Graves' hyperthyroidism. We quantitatively determined the concentrations of urinary F2-isoprostanes using gas chromatography-mass spectrometry in the selected ion-monitoring mode. We recruited individuals in the following three groups of subjects for this study: (1) female hyperthyroidism patients (n = 14, 21-71 years), (2) female hypothyroidism patients (n = 16, 16-66 years), and (3) female age-matched normal controls (n = 10, 20-61 years). The average concentration of 8-iso prostaglandin F(2alpha) (8-isoPGF(2alpha)) in hyperthyroidism patients was significantly higher than that in the healthy controls (P < 0.05). The concentration of 8-isoPGF(2alpha) in hypothyroidism patients was similar to that in normal controls. Although the level of 8-isoPGF(2alpha) in two of the patients was slightly elevated, the P value was not significant (NS). Our data suggest that the increased level of urinary 8-isoPGF(2alpha) may reflect possible oxidation injuries in hyperthyroidism patients due to the high level of thyroid hormones. Therefore, the elevated 8-isoPGF(2alpha) in patients could be used as an important biomarker for hyperthyroidism disease.

Adolescent↗
PubMed2001

Hyperthyroid dementia: clinicoradiological findings and response to treatment.

Dementia associated with hyperthyroidism is less well documented than is hypothyroid dementia. Therapeutic response of hyperthyroid dementia and associated cerebral circulatory and/or metabolic abnormalities has not been elucidated. We described a patient with hyperthyroid dementia and clinicoradiological response to treatment. Single photon emission computed tomographic (SPECT) study was repeated and analyzed semiquantitatively. A 67-year-old man experienced progressive impairments of attention, memory, constructive skills and behavior as well as hand tremor and weight loss of two-year duration. Laboratory findings were compatible with Graves' disease. The initial SPECT showed diffuse tracer uptake defect with an accentuation in the bilateral temporoparietal regions. Clinical and SPECT findings both suggested concurrent "possible" Alzheimer's disease. However, initial treatment with a beta-blocker improved behavior and attention-related cognitive functions as well as tracer uptake in the frontal lobes. Subsequent treatment with additional methimazole then improved memory and constructive abilities when a euthyroid state was established. Uptake defect in the temporoparietal regions also responded gradually to the medication. We suggest that the present patient represent hyperthyroid dementia, which responds favorably to treatment with regard to clinical symptoms and SPECT findings. We also suggest that thyroid function be measured in patients with "possible" Alzheimer's disease because treatable hyperthyroid dementia may not be identified.

Adrenergic beta-Antagonists↗
PubMed2002

Increased stiffness in common carotid artery in hyperthyroid Graves' disease patients.

The present study was undertaken to assess the effect of hyperthyroidism on stiffness in the common carotid artery (CCA) in patients with Graves' disease (GD) and elucidate the mechanism by which arterial stiffness is increased in hyperthyroidism. The arterial stiffness index beta (stiffness beta) was evaluated in the CCA using an ultrasonic phase-locked echo-tracking system. Stiffness beta was defined as the logarithm of the ratio of systolic to diastolic blood pressure divided by the fractional diameter increase during the cardiac cycle and thus established as a measure of arterial stiffness uninfluenced by the change in blood pressure. Seventy euthyroid GD patients were measured for CCA stiffness beta to determine its relationship to retinal blood flow and plasma levels of vascular injury markers. To investigate the effect of hyperthyroidism, 27 GD patients were measured for changes during antithyroid drug (ATD) therapy in stiffness beta and in hemodynamic parameters, retinal blood flow and plasma vascular injury markers. In euthyroid GD patients, stiffness beta in the CCA showed a significant and positive correlation with systolic blood pressure and pulse pressure, but not with peripheral blood flow in the central retinal artery. ATD therapy significantly reduced stiffness beta from 5.23 +/- 2.10 to 4.36 +/- 1.48. The fractional reduction of stiffness beta during ATD therapy correlated significantly with reductions in pulse pressure and retinal blood flow, but not with the reductions in systolic and mean blood pressure, or any of the plasma injury markers. In summary, the significant increase in stiffness beta in the hyperthyroid state may reflect the harmful effect of hyperthyroidism on the arterial wall, which may in turn result from increased stroke volume.

Adolescent↗
PubMed2001

Hyperthyroidism is associated with lengthening of ventricular repolarization.

OBJECTIVE: Lengthened ventricular repolarization, as assessed by the QT interval on electrocardiogram (ECG), can predispose to an increased risk of cardiac dysrhythmias; no data are available on QT corrected for heart rate (QTc) in hyperthyroidism in vivo. DESIGN: QT and RR intervals from 24 h ambulatory ECG Holter recording were measured in patients with hyperthyroidism and again following pharmacological achievement of stable euthyroidism for at least 2 months. PATIENTS: We enrolled a total of 16 hyperthyroid patients with Graves' disease, six males and 10 females (mean age 47 +/- 4 years, mean +/- SEM); 13 healthy age- and sex-matched subjects were utilized as a control group. MEASUREMENTS: The QT analysis was carried out by a computerized algorithm (QTc was corrected by the heart rate by Bazett's formula). Serum total T4, total T3, free T4, free T3 and TSH concentrations were measured by a fully automated immunoenzymometric assay; plasma norepinephrine by automatized high-pressure liquid chromatography, potassium and chloride by a potentiometric method, magnesium and calcium by a colourimetric method. RESULTS: The 24-h average QTc in the hyperthyroid patients was significantly prolonged compared to controls (458 +/- 7 vs. 431 +/- 6 ms, P = 0.01) and it returned to normal after treatment of thyrotoxicosis (432 +/- 6 ms, P < 0.05 vs. time H, NS vs. controls). QTc positively correlated with FT3 (r = 0.63, P < 0.001) and with FT4 (r = 0.481, P < 0.02). Conversely, QTc did not correlate with plasma basal norepinephrine levels, nor with electrolytes. CONCLUSIONS: Hyperthyroidism is associated with prolonged QTc that normalizes once the patient becomes euthyroid. The strong positive correlation between FT3 and QTc supports the hypothesis of an important role of thyroid hormone on modulation of QTc lengthening.

Adrenergic beta-Antagonists↗
PubMed1996

Islet cell and glutamic acid decarboxylase antibodies in hyperthyroid patients: at diagnosis and following treatment.

OBJECTIVES: To study the frequency of islet cell (ICA) and glutamic acid decarboxylase (GAD-Ab) antibodies in patients with hyperthyroidism of different types at diagnosis before treatment and in the euthyroid state following treatment. SETTING: Department of Endocrinology, Malmö University Hospital, Malmö, Sweden. SUBJECTS AND DESIGN: Blood samples were collected at diagnosis from 129 hyperthyroid patients, and about 6 months later, from 78 of the patients (euthyroid state). Ninety-two patients had Graves' disease (69 females and 23 males, median age 49 years, range 17-85 years), and 37 patients had toxic nodular goitre/solitary toxic adenoma (34 females and three males, median age 69 years, range 24-86 years). INTERVENTIONS: Most patients were treated by radioactive iodine following the first blood sample. MAIN OUTCOME MEASURES: ICA and GAD-Ab in serum. RESULTS: At diagnosis of Graves' disease, ICA were detected in two out of 92 (2.2%) patients, two out of 85 (2.4%) without diabetes mellitus and in the euthyroid state in one patient. None of the patients with toxic nodular goitre/solitary toxic adenoma had detectable ICA. At diagnosis of Graves' disease, GAD65-Ab as well as GAD67-Ab were detected in 11 out of 85 (13%) patients without diabetes. As many as six out of 11 GAD67-Ab-positive patients were GAD65-Ab negative. In the euthyroid state, GAD65-Ab were found in six out of 51 (12%) and GAD67-Ab in eight out of 51 (16%) of the non-diabetic Graves' disease patients. The frequencies of GAD65-Ab and GAD67-Ab in toxic nodular goitre/solitary toxic adenoma, diabetes excluded, were 3 and 0%, respectively, in the hyperthyroid state. CONCLUSION: The frequency of ICA in patients with hyperthyroidism is not increased as compared to the background population. GAD-Ab seems to be associated with Graves' disease and not with hyperthyroidism. The presence of GAD67-Ab in GAD65-Ab negative sera from patients with Graves' disease indicates autoreactivity against a specific GAD67 epitope.

Adolescent↗
PubMed2001

TSBAb (TSH-stimulation blocking antibody) and TSAb (thyroid stimulating antibody) in TSBAb-positive patients with hypothyroidism and Graves' patients with hyperthyroidism.

There are two types of TSH receptor antibodies (TRAb); thyroid stimulating antibody (TSAb) and TSH-stimulation blocking antibody (TSBAb). TSAb causes Graves' hyperthyroidism. TSBAb causes hypothyroidism. Both TSAb and TSBAb block TSH-binding to thyroid cells as TSH receptor antibodies (TRAb). TSBAb-positive patients with hypothyroidism and Graves' patients with hyperthyroidism may have both TSBAb and TSAb. We studied TSBAb and TSAb in 43 TSBAb-positive patients with hypothyroidism and in 55 untreated Graves' patients with hyperthyroidism. TSBAb-activities were expressed as percentage inhibition of bovine (b) TSH-stimulated cAMP production by test IgG. Two formulas were used to calculate TSBAb-activities; TSBAb-A (%) = [1 - (c - b)/(a - b)] x 100 and TSBAb-B (%) = [1 - (c - d)/(a - b)] x 100, where a: cAMP generated in the presence of normal IgG and bTSH, b: cAMP generated in the presence of normal IgG, c: cAMP generated in the presence of test IgG and bTSH, and d: cAMP generated in the presence of test IgG. TSAb (%) = [d/b] x 100. All of the 43 TSBAb-positive patients with hypothyroidism had strongly positive TSBAb-A and -B. Some of them had weakly positive TSAb (<240%). All 55 untreated Graves' patients had positive TSAb (205-2509%). Some of them had both TSAb and TSBAb. TSBAb-positive patients with hypothyroidism had a limited distribution of TSBAb- and TSAb-activities (TSBAb-A + 75 - + 103%, TSBAb-B + 87 - + 106%, TSAb 92-240%), but Graves' patients with hyperthyroidsim had a wide distribution of TSAb- and TSBAb-activities (TSAb 205-2509%, TSBAb-A - 158 - + 43%, TSBAb-B - 14 - + 164%). TSBAb-A ignores TSAb activity in serum, and might give low TSBAb activity. However, TSBAb-A clearly differentiates TSBAb-positive patients with hypothyroidism from Graves' patients with hyperthyroidism; thus, we favor TSBAb-A over TSBAb-B. Some of TSBAb-positive patients with hypothyroidism and Graves' patients with hyperthyroidism have both TSBAb and TSAb.

Adult↗
PubMed1986

Factors predicting the course of diabetes mellitus in hyperthyroid patients.

The relationship between changes in glucose tolerance with treatment of hyperthyroidism and various factors that might be relevant to carbohydrate metabolism were investigated in 64 hyperthyroid patients with abnormal glucose tolerance, including 35 cases with fasting plasma glucose (FPG) levels of 140 mg/dl or more. All patients had diffuse toxic goiter. After correction of the hyperthyroidism, glucose intolerance improved in almost all cases, even in cases with fasting hyperglycemia, but diabetes mellitus in patients with FPG above 140 mg/dl and/or delta IRI/delta PG X 30' during a 50-g oral glucose tolerance test below 0.10, persisted. Patients who showed diabetic glucose tolerance even after remission from thyroid dysfunction had significantly lower delta IRI/delta PG X 30' values and a higher incidence of family histories of diabetes mellitus than those not showing diabetic glucose tolerance. There were no significant differences in serum T3 and T4 levels between these two groups of patients. The findings suggest that predisposition to diabetes may be an important factor in persistent glucose intolerance in the hyperthyroidism of Graves' disease. The FPG and delta IRI/delta PG X 30' values may be useful in predicting which patients with hyperthyroidism will have permanent diabetes.

Adolescent↗
PubMed1999

Oxidative stress and anti-oxidant metabolites in patients with hyperthyroidism: effect of treatment.

OBJECTIVE: Oxygen free radicals (OFR) play a role in the pathogenesis of tissue damage in many pathological conditions via the peroxidation of membrane phospholipids. Experimental studies showed an elevated oxidative stress during hyperthyroidism, which is reduced by treatment. Therapy per se might decrease oxidative stress. DESIGN: Fasting plasma levels of thiobarbituric acid reacting substances (TBARS), vitamin E and coenzyme Q10 were measured in 22 hyperthyroid patients, before treatment for their thyroid disease, after 13.9 [SD 9.2] weeks, when they achieved an euthyroid state on thyrostatic drugs, and again after 47.7 [21.0] weeks, off therapy. No patient presented additional risk factors for increased lipoperoxidation and/or increased OFR levels. Smokers were asked to abstain from smoking overnight. METHODS: All analytes were measured by HPLC. RESULTS: In hyperthyroidism, plasma levels of TBARS were increased, whereas vitamin E and coenzyme Q10 were reduced. Average levels of TBARS and antioxidant agents returned to normal in euthyroid patients, without differences in relation to stop of thyrostatic therapy. CONCLUSIONS: Our data confirm the presence of oxidative stress and decreased anti-oxidant metabolites in hyperthyroid patients, which are corrected in euthyroidism, without any influence of thyrostatic drugs per se. Nutritional support with antioxidant agents, which are defective during hyperthyroidism, is warranted.

Adult↗
PubMed1996

Lack of effect of thyroxine in patients with Graves' hyperthyroidism who are treated with an antithyroid drug.

BACKGROUND: Antithyroid drugs are effective in patients with hyperthyroidism due to Graves' disease, but the rate of recurrence after treatment is high. In a recent Japanese study, adjunctive treatment with thyroxine (T4) was associated with a recurrence rate 20 times lower than that among patients who received only an antithyroid drug. If these results are confirmed, combined therapy with an antithyroid drug and T4 might become the treatment of choice for all patients with Graves' hyperthyroidism. METHODS: We treated 111 patients (89 women and 22 men) who had Graves' hyperthyroidism. All patients initially received 40 mg of carbimazole daily for one month. Then one group received carbimazole alone for 17 months (52 patients), and the other group received carbimazole plus T4 for 17 months and T4 alone for 18 months (59 patients). In the carbimazole group, the dose was adjusted after one month to maintain a normal serum thyrotropin concentration. In the carbimazole-T4 group, the dose of carbimazole was not changed, but 100 micrograms of T4 per day was added to the regimen and the dose was adjusted to maintain an undetectable serum thyrotropin concentration (< 0.04 microU per milliliter). RESULTS: At the time of our analysis, 53 of the 111 patients had completed at least 3 months of follow-up (median, 12 months) after carbimazole was withdrawn. Hyperthyroidism recurred in eight patients in each group after a mean (+/- SD) of 6 +/- 4 months in the carbimazole group and 7 +/- 4 months in the carbimazole-T4 group. There was no difference between the recurrence rates in the two groups, despite the fact that serum thyrotropin concentrations were undetectable in 73 percent of patients in the carbimazole-T4 group on at least 75 percent of their visits. CONCLUSIONS: The administration of T4 to patients with Graves' disease during carbimazole treatment and after its withdrawal neither delays nor prevents the recurrence of hyperthyroidism.

Adult↗
PubMed1999

Hypothalamic-pituitary-testicular axis and seminal parameters in hyperthyroid males.

Information on the effect of abnormal thyroid function on male reproduction is less available than that for the female. To assess the effects of hyperthyroidism on hypothalamic-pituitary-testicular axis and on spermogram parameters, 25 male patients (19-47 years old) suffering from active Graves' disease were studied. Serum luteinizing hormone (LH), follicle stimulating hormone (FSH), and prolactin (PRL) were measured before and after administration of 100 microg GnRH plus 200 microg thyrotropin-releasing hormone (TRH). Testosterone (T), estradiol (E2), and 17-hydroxyprogesterone (17-OHP) were determined before and after 5000 IU human chorionic gonadotropin (HCG) administration. Serum sex hormone-binding globulin (SHBG), cortisol-binding globulin (CBG), androstenedione and bioavailable testosterone (bioT), and bioavailable estradiol (bioE2) were also measured. Spermograms according to World Health Organization (WHO) criteria were determined in 21 patients. Hormonal and seminal studies were repeated in six patients after 7 to 19 months of euthyroidism achieved after treatment for hyperthyroidism. As a control group, 10 normal men were evaluated. Impaired sexual function, gynecomastia, and low testicular volume were found in 12, 6, and 3 hyperthyroid patients. Mean basal LH was significantly higher than the control group (7.8 +/- 4.7 vs. 5.0 +/- 1.9 mIU/mL, respectively, p < 0.02), with hyperresponse to GnRH. The response of PRL to TRH was lower in patients versus control group (30 minutes: 3.9 +/- 3.4 and 12.0 +/- 2.8 ng/mL, p < 0.01). Basal levels of steroids and SHBG were significantly higher in patients than in normal men (T: 9.3 +/- 3.3 vs. 5.4 +/- 1.6 ng/mL, p < 0.005; E2: 62.2 +/- 25.2 vs. 32.1 +/- 11.0 pg/mL, p < 0.005; 17-OHP: 2.4 +/- 0.9 vs. 1.1 +/- 0.5 ng/mL, p < 0.001; SHBG: 102.3 +/- 37.3 vs. 19.0 +/- 5.0 nmol/L, p < 0.01). The maximal increment of T and 17-OHP after HCG was lower in hyperthyroid patients than in normal men (p < 0.019 and p < 0.001, respectively). Basal bioT was lower in patients than controls (1.7 +/- 0.8 and 3.1 +/- 1.9 ng/mL, p < 0.02). The following incidence of abnormal semen parameters was found: asthenospermia 85.7%, hypospermia 61.9%, oligospermia 42.9%, necrospermia 42.9% and teratospermia 19.0%. In euthyroidism, a normalization of 85% of seminal alterations was observed in the limited number of patients evaluated. Our results confirm that hyperthyroidism causes marked alterations of the gonadotropic and PRL axis and dramatically affects spermatic function. BioT measurement was useful to identify hypoandrogenism in these patients in spite of the high concentration of total testosterone. The restoration of most semen parameters when euthyroidism was achieved suggests that the alterations were induced by the Graves' disease.

Adult↗
PubMed1983

Insulin sensitivity in hyperthyroidism: measurement by the glucose clamp technique.

Sensitivity to porcine insulin has been compared in overnight fasted hyperthyroid and control subjects using a euglycaemic clamp technique. Basal values for blood glucose, lactate, pyruvate, alanine, serum insulin and C-peptide were similar in the two groups, whilst blood glycerol (hyperthyroid 0.11 +/- 0.02 (mean +/- S.E.) vs. control 0.06 +/- 0.01 mmol/l, P less than 0.01) and blood 3-hydroxybutyrate (0.28 [0.03-0.79, range ]vs 0.09 [0.01-0.29 ]mmol/l, P less than 0.05) were increased in hyperthyroidism. During the 2 hour insulin infusion (0.05 U/kg/h), serum insulin plateaued at the same level (44 +/- 4 vs 44 +/- 1 mU/l) and insulin metabolic clearance rates were similar (1.21 +/- 0.10 vs 1.25 +/- 0.03 l/min). Serum C-peptide levels also decreased by similar amounts (40 +/- 8 vs 47 +/- 6%). The amount of glucose infused to maintain euglycaemia was identical during the second hour of insulin infusion (290 +/- 50 vs 330 +/- 30 mg/kg) as were the increments in lactate and pyruvate concentrations. Blood glycerol values decreased in both groups although values in hyperthyroid patients remained significantly higher than in controls. 3-Hydroxybutyrate concentrations fell to similar values in the two groups. These findings suggest that insulin-stimulated glucose metabolism and inhibition of ketogenesis are normal in hyperthyroidism.

3-Hydroxybutyric Acid↗
PubMed2005

The effect of combination therapy with propylthiouracil and cholestyramine in the treatment of Graves' hyperthyroidism.

OBJECTIVE: The study aims to evaluate the efficacy of combination therapy with propylthiouracil (PTU) and cholestyramine in the treatment of Graves' hyperthyroidism. BACKGROUND: Thyroxine (T4) is metabolized mainly in the liver by conjugation to glucuronides and sulphates that enter the enterohepatic circulation. Thyrotoxic patients have an abnormal increase in thyroid hormone in their enterohepatic circulation. Previous studies on combination therapy with methimazole and cholestyramine for Graves' hyperthyroidism have shown it to be an effective adjunctive treatment. In this study, we examined the efficacy of combination therapy with PTU and cholestyramine in the treatment of Graves' hyperthyroidism. METHODS: Thirty patients with newly diagnosed Graves' hyperthyroidism were randomly divided into two groups: group I (n = 15) received PTU 100 mg twice a day, propranolol 40 mg twice a day and cholestyramine 4 g twice a day for 4 weeks; group II (n = 15) received PTU 100 mg twice a day and propranolol 40 mg twice a day for 4 weeks. The therapeutic efficacy was determined by serum total triiodothyronine (TT3), free thyroxine (FT4) and TRAb levels at baseline, and at the end of 2 and 4 weeks during the study period. RESULTS: There was no significant difference in baseline thyroid function parameters. At the end of 2 and 4 weeks of the study period, serum TT3 and FT4 levels of group I were significantly lower than those of group II. No significant differences in the TRAb level were found between the two groups. CONCLUSION: Cholestyramine contributed to a more rapid and complete decline in thyroid hormone levels in patients with Graves' hyperthyroidism. It was thus proved to be an effective and well-tolerated adjunctive therapy.

Adolescent↗
PubMed2004

Signal transducer and activator of transcription (Stat)-6-dependent, but not Stat4-dependent, immunity is required for the development of autoimmunity in Graves' hyperthyroidism.

The role of T helper (Th) cells in experimental models of Graves' hyperthyroidism is still somewhat controversial. To further investigate the role of Th1- and Th2-dependent immunity during the development of Graves' hyperthyroidism, we tested mice with targeted deletion of signal transducer and activator of transcription-4 (Stat4) or Stat6 genes that, respectively, have impaired Th1 and Th2 immunity. We immunized wild-type BALB/c, Stat4(-/-), or Stat6(-/-) mice with human embryonic kidney cells (293 cells) expressing the extracellular domain of human TSH receptor (293-TBP cells). Fifty percent of wild-type BALB/c and Stat4(-/-) mice developed Graves' hyperthyroidism with elevated serum T(4) levels and thyroid stimulatory antibodies. In contrast, Stat6(-/-) mice resisted development of the disease. Stat4(-/-) mice exhibited a dominant Th2 immune response characterized by the production of IL-4 and IgG1 anti-TSH receptor antibodies. However, Stat6(-/-) mice displayed a strong Th1 immune response characterized by the production of interferon-gamma and IgG2a antibodies. Hyperthyroid mice showed enlargement of thyroid glands with hypertrophy and decreased amounts of colloid material, all characteristics of Graves' disease. These data demonstrate that in this model, Stat6-dependent Th2 immunity is critical for the development of Graves' hyperthyroidism.

Animals↗
PubMed1987

Thyroxine and 3,5,3'-triiodothyronine content of thyroglobulin in thyroid needle aspirates in hyperthyroidism and hypothyroidism.

Thyroglobulin (Tg) was obtained by fine needle aspiration from patients with untreated hyperthyroidism due to Graves' disease and untreated hypothyroidism to determine whether alterations in its T4 and T3 content could account for the disproportionately high serum T3 compared to serum T4 found in both diseases. For comparison aspiration was performed from normal thyroid tissue in euthyroid patients operated for solitary thyroid lesions. The average amounts of Tg aspirated were: normal 177 +/- 52 (SE) micrograms, n = 7, hyperthyroidism 82 +/- 32 micrograms (n = 8); hypothyroidism 4.6 +/- 1.9 micrograms, n = 9. The iodothyronine content of Tg was, normal, T4 3.7 +/- 0.5 mol/mol, T3 0.28 +/- 0.04 mol/mol, T4/T3 13.7 +/- 1.4; hyperthyroidism, T4 3.8 +/- 1.0, T3 0.59 +/- 0.15, T4/T3 6.8 +/- 1.1; hypothyroidism, T4 3.3 +/- 0.5, T3 0.54 +/- 0.09, T4/T3 6.8 +/- 0.7. The iodine content of Tg was 28 +/- 3.1 atoms/mol in the euthyroid subjects and 31 +/- 7.3 atoms/mol in hyperthyroid patients. Hence, both untreated hyperthyroidism and untreated hypothyroidism were characterized by Tg with a normal T4 but a relatively high T3 content. This is probably related to the prolonged hyperstimulation of functioning follicular cells present in both diseases. The relatively high T3 content of Tg could not alone explain the relatively high T3 production compared to T4 production in these two thyroid diseases.

Adolescent↗