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PubMedDate not supplied

Altered responsiveness of coronary arteries in hyperthyroid rats.

The effect of thyroid hormones on vascular responses to various agents was examined in the coronary vascular bed perfused by the Langendorff's method at a fixed flow rate with Krebs-Henseleit solution in isolated rat hearts. In this study, ventricular fibrillation was induced by electrical stimulation to avoid secondary influences derived from alteration of ventricular contractility by agents. Vasodilator responses of coronary arteries to isoproterenol and methacholine were significantly enhanced in hyperthyroid preparations compared with those observed in euthyroid ones, though vasodilator responses to histamine and adenosine were not affected by hyperthyroidism. Vasoconstrictor response to 5-hydroxytryptamine (5-HT) was significantly potentiated by hyperthyroidism though that to balium chloride was not affected. So, these alterations in vascular responses by hyperthyroidism are assumed not to be nonspecific but to be mediator-specific events. As vasoconstriction in coronary arteries lowers oxygen supply to myocardium, enhanced vasoconstrictivity of coronary arteries to 5-HT by hyperthyroidism may be responsible for an exacerbation of heart disease in the case of patients having agglutinative thrombus, which should be a source of 5-HT, in their coronary arteries.

Adenosine↗
PubMed1989

[Results of fractionated radioiodine therapy in 696 patients with hyperthyroidism and 690 patients with non-toxic goiter].

During the course of twenty years 696 patients with hyperthyroidism and 690 cases of non-toxic goitre were treated with 131I in fractionated activities and controlled on an average 4,4 (1-18) years later. Treatment strategy included three special features: a. the first and any further activity amounted to not more than 1.85 MBq per g estimated thyroid weight; b. each therapeutic activity was accompanied by oral prednisone or prednisolone for 2-6 weeks; and c. after completion of radiotherapy each patient was put on thyroid medication which was not interrupted for purposes of control. Therefore, the rate of post-irradiation hypothyroidism could not be determined. All patients were found to be permanently euthyroid and none of the former hyperthyroid patients had relapsed. 84% of the hyperthyroid goitres and 78% of the non-toxic goitres had disappeared completely, 14% and 21%, respectively, were markedly reduced. Complete disappearance of the goitre was achieved with the first 131I activity in 35% of the patients with hyperthyroidism and in 48% of the non-toxic goitres, whereas 34% of the first and 35% of the second group required a second activity; the rest received three or more activities. The mean total activities of 131I necessary for complete reduction of the goitres depended on their size and amounted to 292, 507 and 1136 MBq, respectively, in euthyroid goitres with sizes, I, II and III. The corresponding figures in hyperthyroid goitres were 403, 577 and 1129 MBq, respectively. 314 patients had endocrine ophthalmopathy which was cured in 54% and significantly improved in 37%.

Adult↗
PubMed1989

[Characteristics of the frequency dependence of the contraction force in the hyperthyroid rat myocardium].

We have studied the effect of increased contraction frequency (from 0.2 to 1.5 Hz) on developed tension (delta T) in thin papillary muscles of eu- and hyperthyroid rats. The results show that while increasing the contraction frequency, the delta T of euthyroid papillary muscles decreased at lower frequencies than in hyperthyroid group. Also, at the contraction frequencies above 1.0 Hz the absolute and relative levels of delta T of hyperthyroid myocardium were less decreased than in euthyroid preparations. In conclusion, the myocardium of hyperthyroid rat is characterized by a decreased sensitivity to negative inotropic effect of enhanced contraction frequency. In is probably due to the acceleration of the processes of intracellular Ca2+ recycling during diastole under the influence of hyperthyroidism.

Animals↗
PubMed1988

[Determination of total serum triiodothyronine in hyperthyroidism: comparison of fluorescence polarization and immunoenzymology].

We evaluated the performances of the Abbott fluorescence polarization assay (FPIA) utilizing the TDx system for human total triiodothyronine (T3) in hyperthyroidism. We compared the results with an immunoenzymometric assay (IEA) (Enzymum Test T3 Boehringer-Mannheim). Greatest attention was focused on the diagnosis of hyperthyroidism because detection of subclinical hyperthyroidism is important. The repeatability of the Abbott fluorescence polarization assay was satisfying (m = 8.07 +/- 0.37 nmol.l-1, CV = 4.59%). The reproducibility was tested with Abbott control sera: m = 4.58 +/- 0.53 nmol.l-1 and CV = 11.5 per cent for level M; m = 7.95 +/- 0.66 nmol.l-1 and CV = 8.23 per cent for level H; m = 2.38 +/- 0.39 nmol.l-1 and CV = 16.5 for level L. The correlation of results of the Abbott assay with those of the Boehringer assay was good for samples from hyperthyroid patients. Values for hyperthyroid and euthyroid subjects were resolved slightly better with the Abbott FPIA than with Boehringer IEA. The Abbott total T3 fluorescence polarization assay may have an additional role to play in monitoring thyroid function in patients under iodine treatment (amiodarone) to eliminate a secondary hyperthyroïdism.

Fluorescence Polarization↗
PubMed1985

[Effect of clinical hyperthyroidism and hypothyroidism on patent diabetes. 59 cases].

Fifty-nine patients with both clinical evidence of thyroid dysfunction and patent diabetes mellitus were investigated in our diabetology department. Patients with euthyroid goitre and iatrogenic or pituitary hypothyroidism were excluded from the study. Among the 45 diabetics with hyperthyroidism, 32 had Graves' disease and 13 had toxic adenoma; 71% were insulin-treated. Hyperthyroidism had passed unnoticed in 7 of these 32 patients because fatigue and loss of weight, which initially were the predominant or sole symptoms, are extremely frequent in uncontrolled diabetes. These symptoms, as well as polyuria, polyphagia and even sweating are common to both diseases. Considerable deterioration in the control of glycaemia was observed in 63% of the insulin-treated patients when hyperthyroidism developed, with a 17 to 212% (mean 82%) increase in insulin dosage in 53%. There was no correlation between the degree of hyperthyroidism and the loss of control. Following treatment of the hyperthyroidism, control was improved in 63%, with an 11-83% (mean 44%) decrease in insulin dosage in 59% of them. Insulin therapy could be withdrawn in only one of the 32 insulin-treated patients. Non-iatrogenic primary hypothyroidism was found in 0.2% of the diabetics investigated. This incidence was significantly higher than the calculated probability of the two diseases occurring by chance in the same patient. Eleven out of 14 patients were insulin-treated. When hypothyroidism developed, 73% of them had their insulin dosage reduced, with a high frequency of hypoglycaemic disorders: repeated "malaise" in 55% and coma in 27%. A higher proportion of vitiligo was also noted: 14% in the total patient population reported, and 18% in insulin-treated patients.

Adult↗
PubMed1988

Altered disposition of propylthiouracil in cats with hyperthyroidism.

The oral and intravenous disposition of the anti-thyroid drug propylthiouracil (PTU) was determined in six clinically healthy cats and four cats with naturally occurring hyperthyroidism. Compared with the normal cats, the mean plasma elimination half-life of PTU was significantly (P less than 0.001) shorter in the hyperthyroid cats (77.5 +/- 5.8 minutes compared with 125.5 +/- 3.7 minutes) and the total body clearance of PTU was significantly (P less than 0.05) more rapid in the cats with hyperthyroidism (5.1 +/- 0.8 ml kg-1 min-1 compared with 2.7 +/- 0.2 ml kg-1 min-1). Following oral administration, both the bioavailability (59.7 +/- 4.9 per cent compared with 73.3 +/- 3.7 per cent) and peak plasma concentrations (14.5 +/- 1.6 micrograms ml-1 compared with 18.9 +/- 0.9 micrograms ml-1) of PTU were significantly (P less than 0.05) lower in the hyperthyroid cats than in the control cats. No difference was noted, however, between the apparent volume of distribution for PTU in the two groups of cats. Overall, results of this study indicate that the oral bioavailability of PTU is decreased and PTU disposition is accelerated in cats with hyperthyroidism.

Animals↗
PubMed1988

Lung function and exercise performance in hyperthyroidism before and after treatment.

In order to investigate the mechanism of dyspnoea in hyperthyroidism measurements of spirometry, lung volume, transfer factor for carbon monoxide and its subdivisions, maximal respiratory pressures, methacholine challenge, arterial blood gases were made and exercise studies performed on 16 patients before treatment for hyperthyroidism. Methacholine challenge showed that only three of 14 patients increased airway reactivity, which was mild. Maximal pressures which could be generated by the respiratory muscles were reduced in some patients, as was functional residual capacity. Exercise ventilation and breathing frequency were increased and the respiratory exchange ratio was abnormally high. Anaerobic threshold was measured in nine of 15 subjects and was below normal in each case. All but two subjects stopped exercise because of dyspnoea, and the maximum oxygen uptake achieved by the group was 53 per cent (n = 15, range 26-66 per cent) of predicted maximum oxygen consumption. The maximum ventilation averaged only 43 per cent (n = 15, range 16-96 per cent) of the maximal breathing capacity predicted from spirometric tests. Nine patients were studied shortly after being rendered euthyroid by treatment. At rest, only maximal respiratory pressures increased significantly. On exercise, the maximal workload attained and the ventilation achieved increased significantly. Breathing patterns, maximal oxygen consumption, ventilation, anaerobic threshold and cardiac frequency remained unchanged. We conclude that: patients with hyperthyroidism do not generally have increased airway reactivity; when hyperthyroid, respiratory muscles are weak, and improve following treatment; exercise capacity is impaired in hyperthyroid patients probably because of a combination of an inefficiently rapid and shallow breathing pattern, an increase of anaerobic metabolism and discomfort associated with the act of breathing. Although exercise capacity increases and the sensation of dyspnoea may decrease after treatment the pattern of breathing does not immediately return to normal.

Adult↗
PubMedDate not supplied

[Prolonged hyperthyroidism and recurrent atrio-ventricular block].

The authors report the case of a patient with hyperthyroidism who had three episodes of grade 2 and 3 atrio-ventricular block over a 6-year period. After he recovered from hyperthyroidism, the atrio-ventricular conduction returned to normal and remained so throughout a 5-year follow-up. A grade 1 atrio-ventricular block is found in 6 to 8 p. 100 of hyperthyroid patients, but grade 2 and 3 blocks are rare in such patients. Case reports in which thyrotoxicosis alone seemed to be responsible for disorders of conduction are exceptional; frequently, other factors likely to induce such disorders were present. In 90 p. 100 of the cases hyperthyroidism was due to Graves' disease; it lasted for more than one year and thyrotoxicosis was often severe. These facts suggest the possibility of a thyrotoxic myocarditis and/or an autoimmune focal myocarditis. Although rare, atrio-ventricular block in hyperthyroid subjects is a possibility that warrants electrocardiographic monitoring, notably when negative dromotropic drugs are prescribed.

Adult↗
PubMed1987

Peripheral metabolism of thyroid hormones and iodide in healthy and hyperthyroid cats.

The metabolic clearance rate, volume of distribution, and fractional clearance rate of thyroxine (T4), triiodothyronine (T3), and iodide were calculated for 6 healthy and 7 hyperthyroid cats, using single-compartmental and noncompartmental methods of analysis. The mean T4 volume of distribution of the hyperthyroid cats was 32.0% less than that of the healthy cats; it was the only variable that was significantly different (P less than 0.05) between these 2 groups of cats. The mean fractional clearance rate of T4 in the hyperthyroid cats was 53.2% greater than that in the healthy cats, but this difference was not significant. Hyperthyroid cats had no significant differences in T3 or iodide kinetic variables when compared with those in healthy cats. Single-compartmental analysis significantly overestimated T4 kinetic variables of healthy cats and T4, T3, and iodide kinetic variables of hyperthyroid cats when compared with the noncompartmental method of analysis.

Animals↗
PubMed1985

Radiation associated hyperthyroidism in patients with gynecological malignancies.

To determine the effect of abdominal and/or pelvic irradiation for gynecological malignancies on the later development of hyperthyroidism, 1,884 medical records of the patients diagnoses as carcinomas of cervix and corpus uteri, and of ovary were reviewed. Among 1,269 patients with radiation therapy, 5 patients developed hyperthyroidism after irradiation to the abdomen and/or pelvis. This is a statistically significant increase when compared with an epidemiological study. Radiation dose to the thyroid was estimated to be 30 to 200 rads. Two other patients who were irradiated to the nose or supraclavicular region in addition to the abdomen also developed hyperthyroidism. However, none of 581 patients without radiation therapy became hyperthyroid. The results indicate that radiation therapy for treatment of gynecological malignancy gives a significant radiation exposure with an increase in the incidence of subsequent hyperthyroidism.

Adolescent↗
PubMed1969

Hyperthyroidism with periodic paralysis.

Hyperthyroidism may be associated with hypokalemic periodic paralysis. Two cases are presented demonstrating intermittent attacks of flaccid paralysis associated with clinical symptoms, signs and laboratory findings of hyperthyroidism. During an attack, one patient had a serum potassium of 2.1 mEq. per litre.Various factors such as trauma, exposure to cold, excessive carbohydrate ingestion and certain medications have been stated to precipitate an episode of paralysis. Attacks may range from mild weakness to generalized flaccid paralysis with loss of deep tendon reflexes. Several reported patients have died owing to cardiac arrest or respiratory paralysis.During attacks, the serum potassium is usually in the range of 2.2 to 3.2 mEq. per litre. It is postulated that a metabolic abnormality affecting the muscle-cell membrane can occur in the hyperthyroid state resulting in a shift of potassium to the intracellular position, thus producing a situation of hyperpolarization of the muscle-cell membrane which in turn alters the muscle contractibility.The importance of recognizing the unusual association of hypokalemic periodic paralysis with hyperthyroidism is stressed because, with successful treatment of the hyperthyroidism, the episodes of paralysis disappear.

Adult↗
PubMed1968

Disproportionately higher levels of myocardial docosahexaenoate and elevated levels of plasma and liver arachidonate in hyperthyroid rats.

The effects of hyperthyroidism on the metabolism and distribution of polyunsaturated fatty acids in rats were investigated. The animals were fed diets containing an equal amount (1% each) of linoleate and linolenate. Although the hepatic and plasma levels of the linolenate family of acids were not greatly affected by the hyperthyroidism, the heart of the hyperthyroid rat contained 425% more docosahexaenoate than did that of its euthyroid control. The hyperthyroidism was accompanied by accumulations of 85, 105, and 114% more arachidonic acid in the heart, plasma, and liver, respectively. Nevertheless, most of the total increases in plasma and liver fatty acids were due to the greater accumulations of palmitic, stearic, and oleic acids; the hepatic level of oleate was elevated by 204%. Hyperthyroid rats had 106% more total fatty acids in their hearts, this increase being due largely to the greater accumulation of polyunsaturated acids. The thyroid hormone appears to accelerate the biosynthesis of both arachidonate and docosahexaenoate, and these endogenous polyunsaturated acids are then selectively incorporated into the cardiovascular tissues. Other possible relationships between thyroid action and tissue polyenoic acids in "cold-stressed" animals are discussed.

Animals↗
PubMed1977

Unusual events preceding hyperthyroidism with diffuse goiter.

Two unique patients with hyperthyroidism are presented here. A 48-year-old woman with a family history of Graves' disease was first evaluated and treated for a toxic adenoma with radioactive iodine. Three months later, she was again hyperthyroid, was found to have a diffuse thyromegaly, and was treated with radioactive iodine for the second time. This patient represents, to our knowledge, the first reported case of two sequential forms of endogenous hyperthyroidism. The second patient, a 64-year-old woman, had well-documented hypothyroidism that was presumably primary. She was admitted in thyroid storm and subsequently died. The autopsy disclosed characteristic changes in the thyroid of hyperthyroidism and a normal pituitary gland. The timing of the onset of Graves' disease with hyperthyroidism cannot be accurately determined.

Adenoma↗
PubMed1984

Hyperthyroidism with metastatic follicular thyroid carcinoma.

A 70-yr-old woman presented with hyperthyroidism and metastatic follicular carcinoma of the thyroid. The blood level of thyroid stimulating immunoglobulin (TSIg) was elevated. A total thyroidectomy was performed. One month later she remained hyperthyroid. Three weeks after therapy with 218 mCi of I-131 sodium iodide, the patient was euthyroid. Six months after the initial radioiodide therapy, she was again hyperthyroid and was given a second oral treatment dose of I-131 (220 mCi). Five months later, the patient had again become euthyroid. It is likely that initially the woman's metastases were producing sufficient hormone to render her hyperthyroid. After thyroidectomy and two large doses of radioiodide, she has remained euthyroid without having to take exogenous hormone. The blood level of TSIg had become undetectable. Based on this finding, we offer a tentative classification of the causes of hyperthyroidism in patients with thyroid carcinoma.

Adenocarcinoma↗
PubMed1976

Peripheral blood B-lymphocyte abnormalities associated with hyperthyroidism of Graves' disease.

Proportions of peripheral blood thymus-derived T lymphocytes (T cells) and bone-marrow-derived B-lymphocytes (B cells) were studied in twelve hyperthyroid patients and ninety-nine non-hyperthyroid control subjects including thirty-nine healthy individuals and sixty patients with various disorders. All hyperthyroid patients had Graves' disease and eight were untreated. The sheep erythrocyte (E)-rosetting technique was employed for enumeration of T cells and the immunofluorescent technique was used for identification of lymphocytes with surface immunoglobulins (SIg), a marker for B cells. The results showed that hyperthyroid patients had higher percentages of lymphocytes stainable for SIg, whereas their T-cell proportions were the same as our control values. In addition, approximately half or more of the fluorescein stainable lymphocytes reacted with each of the five antisera against individual heavy chain determinants, including the epsilon chain, indicating the presence of more than three Ig determinants on the same cell. The fluorescein-stainable cells did not form E rosettes. Blocking of the Fc receptor on lymphocytes by incubating the patients' cells with heat-aggregated human IgG or heated goat anti-bovine serum albumin (anti-BSA) failed to abolish the subsequent fluorescent staining of the cells. Incubation of patients' lymphocytes with non-fluorescent anti-epsilon inhibited the subsequent staining of cells with fluoresceinated anti-epsilon but not staining with fluoresceinated anti-mu or anti-gamma. Thus, the study revealed B-cell abnormalities associated with hyperthyroidism, manifested by the simultaneous presence of multiple Ig classes, including IgE, on a single B cell. Results of studies of incubation of the patients' plasmas with lymphocytes from health individuals and studies of SIg by overnight culture of the patients' lymphocytes with or without prior trypsinization suggested that the SIg was generated endogenously by the cell on which it resided.

Adult↗
PubMed1984

[Phonomechanographic evaluation of left ventricular function in hyperthyroid states].

Hyperthyroidism is associated with a hyperkinetic syndrome, the mechanisms of which are not fully understood but which include an increase in heart rate, a reduction in systemic arterial resistance and a debatable increase in myocardial contractility. The limitations of radioimmunological assay of the hormonal mediators underline the diagnostic value of an atraumatic method of quantifying left ventricular systolic function. In view of the variable sensitivity of phonomechanographic and echocardiographic indices with respect to changes in heart rate, pre- and after load, we studied apex cardiographic indices during the phase of isovolumetric contraction. Fifty-eight patients with hyperthyroidism but without patent cardiovascular disease were divided into two subgroups: Grave's disease: 38 cases, and toxic adenoma: 22 cases. The results of the measurements of systolic time intervals and the calculation of "indices of contractility" obtained from the apex cardiogram and its first derivative, were compared with those of 36 young, normal subjects. The results show that: the pre-ejection period of the study population was much shorter than normal (65,7 ms +/- 2,5 vs 84,6 ms +/- 3,4; p less than 0,001); this was clearly related to the chronotropic factor (p less than 0,05). The pre-ejection/ejection period ratio did not differentiate hyperthyroid from normal subjects (0,265 vs 0,283, p greater than 0,20), except in Graves' disease (0,249, p less than 0,02). On the other hand, measurements made from the apex cardiogram showed significant differences in both types of hyperthyroidism. (Formula: see text). In conclusion, phonomechanography may be used to quantify the increase in left ventricular function in hyperthyroidism.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1980

Lymphocytic thyroiditis with spontaneously resolving hyperthyroidism (silent thyroiditis).

Spontaneously resolving hyperthyroidism (SRH) is a transient form of hyperthyroidism characterized by a painless, nontender, normal-sized or slightly enlarged thyroid gland, elevated levels of thyroxine and triiodothyronine, a depressed thyroid radioactive iodine uptake (RAIU), spontaneous resolution in two to five months, and a focal or diffuse lymphocytic thyroiditis on biopsy. Since 1962, 62 episodes of SRH were found in 56 individuals. Twelve thyroid biopsy specimens showed diffuse or focal lymphocytic thyroiditis. Testing of viral antibodies to a wide range of viruses demonstrated only one patient with notable titer change of 18 tested. Resolution of the hyperthyroidism took two to five months. Four patients were treated inappropriately. Lymphocytic thyroiditis with spontaneously resolving hyperthyroidism appears to be a new syndrome that has dramatically increased in frequency in the past ten years. It is difficult to differentiate from common forms of hyperthyroidism unless RAIU is determined.

Adolescent↗
PubMed1978

Use of I-123 in early radioiodide uptake and its suppression in children and adolescents with hyperthyroidism.

Absolute activity measurement of I-123 by coincidence counting was used to study the early thyroidal iodide uptake in 20 hyperthyroid children. Patients were pretreated either with methimazole or propylthiouracil before injection of Na123I. The usual method of analysis of the early uptake was modified to account for a rapidly equilibrating compartment, to give thyroidal iodide trapping rate constant (K1) and absolute iodide uptake (AIU). The suppressibility of the early uptake by triiodothyronine (T3) was evaluated in some patients. The upper limit of normal for K1 was 0.03 min-1 and for AIU was 0.04 microgram/min. In the hyperthyroid subjects, K1 and AIU were in the hyperthyroid range before and after T3 suppression. For patients with suppressible uptake, remission from hyperthyroidism was maintained for 6 mo to 2 1/2 yr. Only two patients with nonsuppressible uptake achieved remission from hyperthyroidism, perhaps because of coexistence of thyroiditis.

Adolescent↗