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PubMed1989

Effect of induced thyroid dysfunction upon uterine responsiveness in strips from pregnant and nonpregnant rats.

The influence of thyroid dysfunction on rat myometrial responsiveness to oxytocin, acetylcholine, CaCl2 and BaCl2 was assessed in uterine strips from pregnant and nonpregnant rats. In preparations obtained from hypothyroid nonpregnant rats, oxytocin and acetylcholine concentration-response curves were significantly displaced to the left, whereas myometrial strips from hyperthyroid nonpregnant rats were only supersensitive to acetylcholine. In relation to the pregnant state, T3 treatment caused an increased myometrial sensitivity to both oxytocin and acetylcholine. In this condition, concentration-response curves for oxytocin did not differ from nonpregnant control animals, whereas acetylcholine was about 300-fold more potent at the ED50 levels compared with those in nonpregnant animals. Either in pregnant or nonpregnant state, maximal responses and ED50 to BaCl2 did not differ. In addition, thyroid dysfunction did not modify the pattern of CaCl2-induced contractions in isolated myometrial strips from pregnant rats. This data extended to the myometrium, previous evidence in the literature indicating that thyroid dysfunction may affect uterine responsiveness to agonists.

Acetylcholine↗
PubMed1990

[Evaluation of a new strategy for detecting thyroid dysfunction].

The results of a diagnostic strategy to evaluate thyroid function were assessed. This strategy consists of TSH measurement as the initial biochemical test, assuming that all individuals with normal TSH concentrations are euthyroid and do not require additional measurements of other hormones. The study was carried out in 576 patients whose serum samples had been referred to the laboratory during 4 consecutive weeks for the evaluation of thyroid function. In all cases TSH and free T4 (FT4) concentrations were measured by chemoluminescence, using one tube for each parameter and patient. Total T3 concentrations (T3) were only measured (RIA) in patients with subnormal TSH values, using duplicate samples. With TSH measurement as the initial test, 447 patients (78%) in whom further hormone assessment would not have been required were detected. This rate would have been 75% if FT4 measurement had been adopted as the screening test. In addition, 55 patients with subclinical thyroid dysfunction were identified with TSH measurement. They would have been missed if the screening had been based on FT4 only. T3 measurement only contributed to the identification of one patient with T3 thyrotoxicosis, and it did not provide additional useful information for the diagnostic classification of the remaining patients. The results of these assays show that TSH measurement is the biochemical test of choice as the first step of a strategy to detect thyroid dysfunction. Its use to this end makes the concomitant measurement of other hormonal parameters unnecessary, resulting in a considerable reduction of cost.

Adolescent↗
PubMed1987

[Study on the screening of thyroidal dysfunction in adult].

For the purpose of screening of thyroidal dysfunction in adult, we have collected blood of 15,905 (male 11,559, female 4,346) adult normal workers and school students on filter papers at the time of the annual health examination. Both TSH and total T4 were measured by radioimmunoassay. Either TSH or total T4 or both showed abnormal values in 148 cases. For these subjects, serum TSH, total T4 and T3, free T4, TBG, antimicrosomal and antithyroglobulin antibody were estimated. From these results, diagnosis was made as follows: 6 hyperthyroidism, 12 primary hypothyroidism (including 3 subclinical hypothyroidism who showed elevated TSH and normal free T4 values) and 29 TBG abnormality (increase: 8, decrease or deficiency: 21). The incidence by this study was: hyperthyroidism 0.038% (1/2650), primary hypothyroidism 0.075% (1/1330), TBG increase or deficiency 0.132% (1/760). Sex ratio of thyroidal dysfunction were higher in female than male. In hyperthyroidism, ratio of male to female was 1:2.66, and in hypothyroidism, it was 1:133. Most of these patients were not diagnosed before this screening. The fact that the incidence of hypothyroidism was higher than hyperthyroidism in this population was apparent in this study. TBG abnormality was noted more in male than female. This report is important to show the incidence of thyroidal abnormalities and the necessity of the screening test of thyroid in adult.

Adult↗
PubMedDate not supplied

Effects of thyroid dysfunction on prednisolone and prednisone interconversion and disposition in the rat.

The effects of thyroid dysfunction on the reversible metabolism and disposition of prednisolone and prednisone were examined in male Wistar rats. Hyperthyroid rats were produced by daily ip injections of 20 micrograms of I-triiodothyronine/100 g body weight for 6 days. Hypothyroid rats were obtained by providing 0.05% 6-propyl-2-thiouracil in drinking water ad libitum for 21 days. Rats were given 10 mg/kg of prednisolone or prednisone iv, blood samples were collected, and the steroids in plasma were assayed by HPLC. A recently developed pharmacokinetic model encompassing interconversion kinetics was applied. Unexpectedly, the hyperthyroid state increased the AUC (by 163%) of prednisolone (unlike in man) via reduced (66%) prednisolone elimination clearance (CL10), but also caused enhanced (101%) prednisone elimination clearance (CL20). The hypothyroid state increased the AUC (by 117%) of prednisolone via a 56% reduction in CL10 and a reduction in CL20. Prednisone formation of prednisolone (CL21) was about 13-fold greater than the reverse process (CL12), and both interconversion clearances were increased 20-40% by thyroid dysfunction. Experimental thyroid disorders thus alter prednisolone/prednisone pharmacokinetics in rats primarily by selective and sometimes unusual changes in elimination clearance rather than affecting the relative rates of steroid interconversion. Reversible metabolism is much less important in rats compared to man.

Animals↗
PubMed1990

Thyroid dysfunction in adults over age 55 years. A study in an urban US community.

The prevalence of thyroid dysfunction was determined in a healthy urban population over the age of 55 years. A highly sensitive serum thyrotropin assay was used initially to screen 968 subjects. Elevated values (greater than 6 mU/L) were found in 7.3%, while suppressed values (less than 0.1 mU/L) were present in 2.5% subjects. Protirelin stimulation testing demonstrated exaggerated responses in 95% of the subjects with elevated thyrotropin levels and subnormal responses in 81% of the subjects with suppressed thyrotropin levels. Thyroid dysfunction, as defined by abnormalities of both serum thyrotropin level and protirelin response, was calculated to be present in 8.9% of the population. The prevalence was greater in whites (vs blacks), in women, and in subjects older than 75 years as compared with the 55- to 64-year age group. Hypothyroidism was calculated to be present in 6.9% subjects. Despite an increased prevalence of thyroid autoantibodies in these subjects, only 8.5% of them had subnormal serum thyroxine concentrations. Hyperthyroidism was calculated to be present in 2.0% of the population, two thirds of whom were taking thyroid hormone preparations. These results suggest a significant prevalence of thyroid dysfunction in the elderly, with important sex and racial differences.

Aged↗
PubMed1976

Thyroid dysfunction in uremia: evidence for thyroid and hypophyseal abnormalities.

Disturbances in thyroid function and a high prevalence of goiter develop in patients on chronic hemodialysis. This study shows that in patients on dialysis, mean serum thyroxine and triiodothyronine levels are lower than normal. Patients with chronic renal failure not on dialysis, have mean serum thyroxine levels similar to normal subjects and low mean serum triiodothyronine levels. However, both serum thyroxine and triiodothyronine concentrations decrease as the renal failure worsens. In addition, both groups of patients with renal failure have a decreased serum thyroxine response to oxogenous thyrotrophin and a diminished serum thyrotrophin response to thyrotrophin-releasing hormone. These data suggest the presence of an intrathyroidal and an hypophyseal defect in uremic patients. Although serum iodide concentrations are elevated, there is no correlation between the level of serum iodide and the degree of renal failure. Therefore, we have no direct evidence that iodide excess is responsible for the abnormalities observed.

Adolescent↗
PubMed1991

[Thyroid dysfunction and histologic correlation using thyroid needle biopsy specimens].

In this article, we describe the usefulness of thyroid needle biopsy in the differential diagnosis of thyroid disorders revealing unusual thyroid function. Firstly, we describe the relationship between thyroid function and its histology in 601 cases of chronic thyroiditis. In the histologic group A, the majority of the cases showed a latent or overt hypothyroidism and in histologic group B, hyperthyroid, euthyroid and latent hypothyroid cases were found in nearly equal frequency, respectively. In histologic group C, most cases were in euthyroid and in histologic group D, most cases showed a hyperthyroidism. In the silent thyroiditis and postpartum thyroiditis, known to show a characteristic clinical and laboratory finding, the histologic features of thyroid gland were as follows: the observed characteristic histologic changes in both diseases were an extensive follicular destruction associated with chronic diffuse thyroiditis. These destructive changes disappeared in association with the clinical and laboratory recovery. In the patients with iodine-excess hypothyroidism, the thyroid glands also revealed characteristic histologic changes. A marked hyperplastic change of follicular cells and a lack of colloid material in the follicular lumen was the predominant histologic feature. Based on our personal experiences, thyroid needle biopsy should be recommended as a useful tool for differentiation of causes of hyper- or hypothyroidism.

Adult↗
PubMed1991

Thyroid function tests and diagnostic protocols for investigation of thyroid dysfunction.

Since many tests to investigate thyroid function are currently available, appropriate selection is required to limit the number of assay needed to establish the correct diagnosis of thyroid dysfunction. The limitations inherent in the different tests, and the interferences caused by nonthyroidal factors, especially drugs, must, therefore, be taken into account. Serum total thyroid hormone (TT4 and TT3) determinations are largely affected by changes in the concentrations of thyroid hormone transport proteins (mainly T4-binding globulin). Thus, in many cases, serum TT4 and TT3 measurements do not reliably establish thyroid status. Serum free thyroid hormone (FT4 and FT3) concentrations are independent of transport proteins and more appropriately reflect thyroid status. Serum FT3 measurement is more appropriate for the diagnosis of hyperthyroidism and drug-overdosage in L-T4-treated patients. Conversely, serum FT4 measurement more correctly identifies hypothyroid patients. Serum TSH determination by the currently available sensitive (low detection limit) assays constitutes an indispensable complementary test in both conditions.

Algorithms↗
PubMed1987

[Thyroid dysfunction following external irradiation of the neck].

Thyroid function after radiation therapy to the neck was studied in 120 patients, 110 of whom were suffered from malignant lymphomas. No patients had clinical symptoms from thyroid dysfunction, but 9 patients were given thyroid hormone after examination of thyroid function test. TSH elevation rate for 95 patients irradiated to the hole neck by dosage was 0%, 24%, 47% and 47%, for less than 30 Gy, 30-39 Gy, 40-49 Gy and 50 Gy or more, respectively. The effects of lymphangiography and systemic combination chemotherapy on the thyroid function were also discussed.

Adolescent↗
PubMed1989

Effect of thyroid dysfunction on thigh muscle efficiency.

To establish whether muscle weakness in thyroid dysfunction can be attributed solely to muscle atrophy (i.e. reduction in the total muscle cross-section) or whether the intrinsic contractile strength of the muscle is reduced per unit cross-sectional area, the ratio between thigh muscle strength and thigh muscle area was determined before and after treatment of hyper- and hypothyroidism. Midthigh muscle areas, assessed by computer tomography, increased in all seven hyperthyroid and decreased in three of four hypothyroid patients investigated after treatment of the thyroid disease. Peak torque and total work output, assessed by an isokinetic dynamometer (Cybex II), increased in both groups of patients. The muscle efficiency (total work output per cm2 muscle) increased in all patients after therapy [mean +/- SD values before vs. after therapy in hyperthyroid patients, 17.6 +/- 5.3 vs. 30.5 +/- 3.7 joules (J)/cm2 (P less than 0.001); in hypothyroid patients, 12.8 +/- 6.1 J/cm2 vs. 25.8 +/- 8.6 J/cm2 (P less than 0.05)]. Thus, the present study demonstrates that patients with thyroid dysfunction have altered muscle mass and diminished muscle efficiency.

Adult↗
PubMed1990

Medical needs in the evaluation of thyroid dysfunction.

The clinical examination has low sensitivity and specificity for the diagnosis of thyroid dysfunction. There is still, however, no consensus as regards the cost-effectiveness of biochemical screening for thyroid dysfunction; of possible target groups women post partum might be of particular interest. Current methodological developments center around thyrotropin (TSH), free thyroxine (T4), anti-thyroperoxidase antibodies and indicators of thyroid hormone action, and topics of main concern are the precision at low TSH concentration, the calibration of free T4 assays, and the precision of those assays of free T4 which claim higher accuracy compared with "one-step" methods. Thyroid function indices in non-thyroidal illness continue to confuse assayists. The clinical spectrum of conditions which lead to low serum TSH concentration is insufficiently explored.

Clinical Laboratory Techniques↗
PubMed1988

Prevalence of thyroid dysfunction in elderly subjects. A randomized study in a Norwegian rural community (Naerøy).

The prevalence of thyroid dysfunction was investigated in a small, rural community located at the coast in Middle Norway. Two hundred persons (114 women and 86 men) of the total 802 persons over 70 years of age in the community were examined regarding thyroid dysfunction. Blood samples were drawn from 197 (113 women and 84 men). In women previously diagnosed hypothyroidism was found in 3.5% and previously diagnosed hyperthyroidism in 0.9%. In men no previously diagnosed thyroid disease was found. Undiagnosed primary hypothyroidism (TT4 less than 70 nmol/l and TSH greater than 6 mU/l) was found in 1.8% and 1.2% of women and men, respectively. Latent hypothyroidism (TT4 70-150 nmol/l and TSH greater than 6 mU/l) was found in 3.5% and 2.4%, and borderline hypothyroidism (TSH 4.5-6.0 mU/l) in 3.5% and 2.4%, respectively. Undiagnosed hyperthyroidism was not found in women but in 1.2% of men. Antibody to the thyroid microsomal antigen (TMA) greater than or equal to 400 was detected in 17.5% of women and 9.6% of men. Clearly elevated serum thyrotropin (TSH) concentrations or previously diagnosed thyroid disease were found in 21.7% and 37.5% of the TMA positive women and men, respectively.

Age Factors↗
PubMed1985

Thyroid dysfunction in Down syndrome.

We investigated the thyroid function of 151 patients with Down syndrome. Compared with a control group of 89 siblings nearest in age to their brother or sister with Down syndrome, the mean thyroid-stimulating hormone (TSH) value was significantly higher in patients with Down syndrome than in subjects without Down syndrome. However, the mean thyroxine (T4) levels in both groups were nearly the same. In the Down syndrome group there was a trend for TSH values to increase and for T4 values to decrease with advancing age. Of the 151 patients with Down syndrome, ten had both significantly elevated TSH levels (greater than or equal to 9.5 microU/mL) and significantly decreased T4 levels (less than or equal to 5.5 micrograms/dL), 21 had only abnormally high TSH values, seven had only markedly increased T4 levels (greater than or equal to 12.0 micrograms/dL), and three had only significantly decreased T4 levels. The intellectual function of patients with both abnormal TSH and T4 levels was significantly lower (mean IQ, 41.7) than that of Down syndrome patients with only increased TSH values (mean IQ, 53.8) and that of Down syndrome patients with normal thyroid function (mean IQ, 55.3). This study provides further evidence that there is an increased prevalence of thyroid dysfunction in patients with Down syndrome.

Adolescent↗
PubMed1985

Thyroid dysfunction and neoplasia in children receiving neck irradiation for cancer.

The reported relationship of radiation exposure and thyroid carcinoma stimulated this retrospective study of 298 patients treated at St. Jude Children's Hospital with radiation therapy to the neck for childhood cancer to identify patients who developed subsequent thyroid abnormalities. This series includes 153 patients with Hodgkin's disease, 95 with acute lymphocytic leukemia, 28 with lymphoepithelioma, and 22 with miscellaneous tumors. Inclusion in the study required 5 years of disease-free survival following therapy for their original tumor, which included thyroid irradiation. Follow-up has been 100%. Most patients also received chemotherapy. Seventeen patients were found to have decreased thyroid reserve with normal levels of free triiodothyroxine (T3) or free thyroxin, (T4) and an elevated level of thyroid-stimulating hormone (TSH). In nine patients hypothyroidism developed, with decreased T3 or T4 levels and an elevated level of TSH. One hyperthyroid patient was identified. Two patients had thyroiditis, and seven had thyroid neoplasms: (carcinoma in two, adenoma in two, colloid nodule in one, and undiagnosed nodules in two). This survey has demonstrated an increased incidence of thyroid dysfunction and thyroid neoplasia when compared to the general population. The importance of long-term follow-up for thyroid disease is emphasized in patients who have received thyroid irradiation. The possible role of subclinical hypothyroidism with TSH elevation coupled with radiation damage to the thyroid gland as a model for the development of neoplastic disease is discussed.

Adolescent↗
PubMed1992

Usefulness of thyroglobulin antibody detected by ultrasensitive enzyme immunoassay: a good parameter for immune surveillance in healthy subjects and for prediction of post-partum thyroid dysfunction.

OBJECTIVE: Using newly developed ultrasensitive enzyme immunoassay (EIA) for thyroglobulin antibody (TgAb), we have evaluated physiological and pathological implications of the antibody in healthy subjects as well as in autoimmune thyroid diseases. MEASUREMENTS: This EIA was based on the immune complex transfer method, and was 10(4)-fold more sensitive compared with the conventional haemagglutination assay (HA); the detection limit was 0.1 micrograms IgG/I, and the specificity of the assay was confirmed from the unequivocal decrease in the fluorescence intensity by the preincubation of test serum with Tg and/or inactive beta-D-galactosidase which blocks antibodies to the enzyme. RESULTS: TgAb was detectable in 159 (91%) of 175 healthy subjects aged 3rd to 7th decade (96 men and 79 women), and did not exhibit age or sex-associated change. In nine healthy women, the TgAb level significantly decreased as pregnancy progressed but increased transiently after delivery. TgAb was detectable in 52 (98%) of 53 patients with Graves' disease and all (100%) of 107 patients with chronic thyroiditis. Abnormal high TgAb values (> 40 micrograms/I), determined from the 95th percentile in healthy subjects, were shown in 40 (75%) with the former disease and 94 (88%) with the latter disease. Moreover, in 14 goitrous patients with biopsy-proved chronic thyroiditis with negative HA results, 12 (86%) showed abnormal high TgAb levels. In 69 patients with post-partum thyrotoxicosis in Graves' disease, 15 (79%) of 19 patients with the TgAb level of more than 2 x 10(3) micrograms/I in early pregnancy showed destructive thyrotoxicosis and 46 (92%) of 50 with less than this level showed stimulative thyrotoxicosis. This TgAb test could discriminate the two types of thyrotoxicosis more clearly than could the conventional TGHA test. In chronic thyroiditis, the mean TgAb value in early pregnancy was significantly higher in patients with postpartum hypothyroidism than in those without thyroid dysfunction. Hypothyroidism developed in 80% of the patients with a TgAb value of more than 10(3) micrograms/I. CONCLUSIONS: The ultrasensitive TgAb EIA was useful for detecting the physiological changes in autoantibody formation in healthy subjects and the TgAb value was useful for predicting post-partum thyroid dysfunction in autoimmune thyroid diseases. This EIA is useful for the evaluation of the immune surveillance in patients with autoimmune thyroid diseases as well as in healthy subjects.

Adult↗
PubMed1991

Asymptomatic autoimmune thyroiditis and thyroid dysfunction in Alport's syndrome. A report of three families.

The purpose of this study was to investigate the significance of serum antithyroid antibodies in Alport's syndrome. Thyroid microsomal and thyroglobulin antibodies were assessed in three families with Alport's syndrome for a total of 11 patients and 17 healthy relatives, as well as in 40 haemodialysis patients and in 40 healthy subjects. Thyroid function tests, including the measurement of serum total thyroxine (TT4), total triiodothyronine (TT3), free thyroxine (fT4) and free triiodothyronine (fT3) concentrations, and thyrotropin-releasing hormone (TRH) stimulation tests were performed in all patients and subjects. Among patients with Alport's syndrome, five (45%) had elevated titres of thyroid microsomal antibodies and eight (73%) had positive titres of thyroglobulin antibodies, whereas only one healthy relative (6%) had circulating antithyroid antibodies. Fine-needle aspiration biopsy of the thyroid demonstrated a lymphocytic infiltration that indicated the existence of asymptomatic autoimmune thyroiditis in all five patients with elevated thyroid microsomal antibody titres. The prevalence of antithyroid antibodies in healthy subjects and in haemodialysis patients was 7.5% and 12.5% respectively. Functional tests demonstrated a thyroid dysfunction in four of five patients with asymptomatic autoimmune thyroiditis. Two patients had evidence of subclinical hypothyroidism. Two other patients, both with end-stage renal failure, showed a blunted TSH response to TRH, increased fT4 and elevated borderline fT3. The present study indicates that elevated titres of serum antithyroid antibodies may be detected in patients with Alport's syndrome. These patients are at risk of developing asymptomatic autoimmune thyroiditis and thyroid dysfunction. Subclinical hypothyroidism and, perhaps, preclinical hyperthyroidism may be found in these patients.

Adult↗
PubMed1976

Thyroid dysfunction in female psychiatric patients.

Biochemical screening for thyroid dysfunction in 98 unselected female psychiatric admissions led to the diagnosis of hypothyroidism in three cases which would otherwise have passed unrecognized. It is suggested that female psychiatric patients over the age of 40 should routinely be screened for thyroid disorder.

Adult↗
PubMed1990

Exacerbation of autoimmune thyroid dysfunction after unilateral adrenalectomy in patients with Cushing's syndrome due to an adrenocortical adenoma.

Little is known about the factors that cause exacerbations of autoimmune thyroid dysfunction. One possibility is an alteration in adrenocortical function, since glucocorticoids are known to alter both pituitary-thyroid and immunologic function. We encountered three patients in whom overt autoimmune thyroid disease developed after unilateral adrenalectomy for Cushing's syndrome due to an adrenocortical adenoma. We compared the postoperative changes in thyroid function in these patients with those in 21 other patients with Cushing's syndrome who underwent the same treatment. After unilateral adrenalectomy, one of the three patients had transient hyperthyroidism and a low thyroid uptake of 131I, indicative of silent thyroiditis. After the same surgical procedure, the second patient had hypothyroidism, where-as the third patient had transient hyperthyroidism at first, and hypothyroidism then gradually developed. All three patients had serum antithyroid antibodies, the titers of which increased after surgery. In the remaining 21 patients (only 2 of whom had antithyroid antibodies initially), the serum concentrations of thyroxine, triiodothyronine, and thyroxine-binding globulin and the secretion of thyroid-stimulating hormone increased after surgery from values that were low or near the lower limit of normal to values still well within the normal range. None of these patients had clinically evident thyroid disease or increased antithyroid-antibody titers. We conclude that reductions in the secretion of glucocorticoid may exacerbate subclinical autoimmune thyroid disease. Patients with Cushing's syndrome due to adrenocortical adenoma who have thyroid antibodies should be followed closely after treatment, because thyroid dysfunction may develop.

Adenoma↗