Risk Of Hyperthyroidism Research Articles

PENGARUH PEMBERIAN GARAM BERIODIUM TERHADAP KADAR TIROKSIN PADA IBU USIA SUBUR DI DAERAH ENDEMIK DEFISIENSI IODIUM

THE EFFECT OF IODIZED SALT INTERVENTION ON THYROXINE OF CHILDBEARING AGE MOTHERS IN ENDEMIC IODINE DEFICIENCY AREA The national evaluation on implementation of Iodized salt indicate an excess dietary intakes of iodine. It is a consequence of the correction of iodine deficiency. However there is no confirmation of the adverse effect to the excess in Indonesia. Our aim is to elaborate whether the excess of iodine consumption affect serum thyroxine. We supplied 50-ppm iodized salt to 82 mothers at childbearing age’s family every two weeks for three months. We suggest the mothers used the supplied iodized salt for family consumption only and not used the salt for any other purposes such as cattle feeding. Mother’s blood drawn before and after intervention. Urine iodine exretion (UIE) were collected from school age children of participant family. The study revealed that three month-iodized salt intervention increased median UIE by 18.4 % and serum thyroxine level by 36.5 %. The number of children being at risk for hyperthyroidism were constributed from normal and deficit range level at initial study by 62,5 % and 41.7 % respectively. The number of mothers being thyroxine excess were 22.2 and 22.7 % respectively. We conclude that the level of iodine consentration in salt at 50 ppm is high and suggest that consentration should be lowered. Keywords : EIU, at risk for hyperthyroidism, thyroid hormone excess.mother at child bearing age.

Risk of hyperthyroidism in a Tunisian population of smokers

This study aimed to examine the effect of cigarette smoking on thyroid function especially TSH and FT4 levels and to determine the correlation between these parameters and the biological tobacco markers: plasma thiocyanate and cotininuria. The initial study was conducted on 300 voluntary subjects, 162 current smokers, 27 former smokers and 111 nonsmokers aged respectively 35.4±16.1, 31.6±1.8 and 38.0±14.6 years. TSH and FT4 levels were determined using electrochemiluminescence, cotinine by homogenous enzymes immunoassay and thiocyanate by selective electrode. Before and after adjustment for potentials confounder factors, we found a significant decrease of TSH and a significant increase of FT4 levels according to smoking status. In current and former smokers, we found significant decrease in TSH and increase in FT4 levels compared to nonsmokers. Moreover, we noted a significant decrease of TSH levels in subjects smoking more than 40 cigarettes/day compared to those smoking less than 20 cigarettes/day. Additionally, TSH levels were significantly reduced in subjects smoking more than 5 years compared to those who smoked < 5 years. In smokers, cotininuria and plasma thiocyanates presented a negative correlation with TSH and a positive correlation with FT4 levels. cigarette smoking is associated to perturbations in FT4 and TSH levels, these perturbations were strongly correlated with smoking status parameters. The associations with smoking cessation suggest that smoking may have reversible effects on thyroid function. Therefore, it is recommended to stop or reduce smoking and to introduce testing of thyroid estimation as a routine test, especially in subjects at risk.

81st Annual Meeting of the American Thyroid Association SHORT CALL ABSTRACTS

81st Annual Meeting of the American Thyroid Association SHORT CALL ABSTRACTS

An effective analysis of screening strategies for thyroid disorders during early pregnancy

Objective To use the first trimester-specific reference intervals of thyroid-related hormones to explore the prevalence of thyroid dysfunction during early pregnancy and to analyze effectiveness of different screening strategies. Methods In this study 2 899 pregnant women were enrolled during the first trimester of gestation. TSH, FT4, FT3, and thyroid peroxidase antibody （TPOAb） were measured and thyroid disorders of pregnant women were diagnosed based on the first trimester-specific reference intervals. Results The prevalence of hypothyroidism was significantly higher in the high-risk group than in the non-high risk group （ 16.3% vs 5.3%,RR = 3.1,95% CI 2.4-4.0, P〈0.01 ）. TPOAb （ RR = 4.7, 95 % CI 3.6-6.0, P〈0.01 ）, and personal history of thyroid diseases （ RR=3.2, 95% CI 1.9-5.4, P〈0.01 ） increased the risk of hypothyroidism. The prevalence of hyperthyroidism was higher in the high-risk group （3.1% vs 1.4%, P = 0. 006, RR = 2.2, 95% CI 1.2-3.9, P=0.006）. TPOAb （RR=2.6, 95%CI 1.3-5.0, P=0.007）, and presence of personal history of thyroid diseases（ RR=4.7, 95% CI 1.7-12.5, P=0.006） also increased the risk of hyperthyroidism. 56.7% women with hypothyroidism and 64. 7% women with hyperthyroidism were in the non-high risk group. Conclusion We recommend that screening all pregnant women for thyroid disorders in the first trimester with TSH, FT4, and TPOAb is more effective than the case-finding approach. Key words: First trimester pregnancy ; Screening; Thyroid dysfunction ; Risk factors

Thyroid functions in paints production workers and the mechanism of oxidative-antioxidants status

Assessment of occupational exposure to paints production chemicals mainly organic solvents in production of thyroid dysfunction and the mechanism of oxidative-antioxidant imbalance. Triiodothyronine (T(3)), thyroxine (T(4)), malondialdehyde (MDA), nitric oxide (NO) and total antioxidants was measured in 36 workers and 40 controls. T(3) and T(4) were elevated in 18.8% and 44.4% of the workers, respectively. T(3), T(4), MDA and NO levels were significantly higher in workers compared to controls. Total antioxidants was significantly lower in workers than in controls. T(3) and T(4) were significantly correlated with duration of exposure, while, total antioxidants was inversely correlated. In workers, T(3) was significantly correlated with MDA and inversely correlated with total antioxidants levels. MDA and NO were significantly higher in workers with abnormal T( 4) than normal workers. Workers exposed to organic solvents proved to be at risk for hyperthyroidism. Oxidative-antioxidant imbalance was found to have a significant role in development of hyperthyroidism with increasing duration of exposure.

Evaluation of risk in autonomously functioning thyroid nodules.

Based on iodine deficiency in Germany autonomous functioning nodules develop and are loaded with the risk of hyperthyroidism. Even subclinical hyperthyroidism has health implications including general symptoms, diseases of the cardiovascular system (atrial fibrillation, risk of thrombembolism, stroke and other embolic events) and a reduction of axial bone mineral density. Fortunately functional nodules have a very low probability of being malignant. However, there exist a coexistence of thyroid carcinoma outside the hot nodule.

Schilddrüsenerkrankungen in der Schwangerschaft

Thyroid disorders may not only be the cause infertility but also increases the incidence of miscarriages and the morbidity of the pregnancies. During pregnancy the demand of thyroid hormones increases to about 30 - 50 % and the thyroid has to cope with this increase. In Germany the iodine intake has improved significantly during the last 20 years, but still is borderline low with an mean intake of about 120 microg iodide per day. Therefore it is still recommended that pregnant women are supplemented with about 100 - 150 microg of iodide during pregnancy and the time of breast-feeding, to avoid hypothyroidism of the foetus with concomitant delay of the brain development. Not only women with subclinical hypothyroidism, but only elevated TPO antibodies have a significant increase in early miscarriage and preterm delivery. An early supplementation with Levothyroxin despite euthyroidism might reduce these risks. Those women also more frequently develop postpartum thyroiditis. This risk can be reduced by a supplementation with selenium during and after pregnancy. Graves' disease is a rare disorder and only about 0,1 - 0,4 pregnancies are affected. The course of the disease is biphasic, with an exacerbation within the first trimester and an improvement thereafter, but a recurrence after delivery. Overt thyrotoxicosis has to be treated with propylthiouracil, to maintain euthyroidism during pregnancy. The TSH receptor antibodies are transferred to the foetus with the risk of thyrotoxicosis. Special care of the foetus is therefore necessary. Transient mild hyperthyroidism may occur in women with very high HCG levels during the first three months of pregnancy. This often is associated with hyperemesis gravidarum. Subclinical hypothyroidism of the mother will disturb the normal development of the foetus and therefore has to be treated even when TSH is within the upper normal level. Special care is necessary in women with elevated TPO antibodies, because these more often develop postpartum thyroiditis.

Hyperthyroidism after parathyroid exploration

We hypothesized that hyperthyroidism after parathyroid exploration may be an underreported phenomenon with a course more severe than recognized previously. We examined pre- and postoperative thyroid function and outcomes in 199 consecutive patients who, since March 2000, had parathyroid exploration for primary sporadic hyperparathyroidism (HPTH). We excluded patients with prior thyroid or parathyroid surgery, preoperative thyroid medication, concurrent total thyroidectomy, or follow-up <5 months. Of 125 patients with normal preoperative serum thyroid-stimulating hormone levels, 39 (31.2%) were hyperthyroid postoperatively. Mean thyroid-stimulating hormone levels (mean +/- SD) dropped with operation from 2.0 +/- 1.1 microIU/mL to 1.2 +/- 1.4 microIU/mL (P < .0001). Nineteen patients (15%) reported symptoms 1 to 2 weeks after operation. The clinical course of hyperthyroidism typically was short, but 5 patients (4%) had symptomatic hyperthyroxinemia requiring medical therapy. Hyperthyroidism was independent of age, severity of HPTH, anatomic/pathologic features, operative time, and other measures of operative difficulty, but was associated with lithium therapy, bilateral exploration, and absence of concurrent thyroid lobectomy. Risk of hyperthyroidism may be underappreciated after routine parathyroid surgery for HPTH. Use of lithium and degree of dissection appear contributory. Patients undergoing parathyroid exploration need counseling and surveillance for hyperthyroidism, which may be reduced by minimizing the extent of parathyroid surgery.

Scintigraphy for Risk Stratification of Iodine-Induced Thyrotoxicosis in Patients Receiving Contrast Agent for Coronary Angiography: A Prospective Study of Patients with Low Thyrotropin

The risk of iodine-induced thyrotoxicosis in euthyroid patients receiving iodine-containing contrast agents is known to be low, but data on this risk in patients with latent hyperthyroidism are scarce. We investigated the role of thyroid scintigraphy using Tc-99m preceding the application of iodine-containing contrast material to estimate the risk of iodine-induced thyrotoxicosis in patients with low levels of TSH. In a prospective study on 91 patients, thyroid scintigraphy was performed before coronary angiography (CA). In patients with technetium thyroid uptake (TCTU) less than 1%, CA was done without prophylactic drugs (n = 56). Patients with TCTU greater than 1% were treated either with 900 mg of perchlorate or, depending on the autonomous volume, combined with 20 to 60 mg thiamazole. In the 56 patients with TCTU less than 1%, no case of iodine-induced hyperthyroidism occurred within 4 wk after CA. In the patients who received prophylactic drugs, two cases of mild thyrotoxicosis were observed. Our data suggest that in patients with low levels of TSH, the risk of hyperthyroidism after application of iodine-containing contrast media is negligible if TCTU is less than 1%. In these patients, CA can be performed without administration of prophylactic drugs.

Thyroid function, thyroid immunoglobulin status, and urinary iodine excretion after enteral contrast-agent administration by endoscopic retrograde cholangiopancreatography.

The aim of this study was to examine the occurrence of clinically relevant changes in thyroid function after enteral administration of contrast agent by endoscopic retrograde cholangiopancreatography (ERCP). In this study 70 patients without a history of thyroid disease who had not recently undergone thyroid-specific or thyroid-influencing therapy were examined. Patients were examined on two or three occasions using a standardized questionnaire regarding symptoms of hypothyroidism and hyperthyroidism. The parameters of thyroid function (TT3, TT4, FT4, thyroid-stimulating hormone (TSH)) and urinary iodine excretion were measured on day 0 and on day 21 post-ERCP, and in 23 patients additionally on day 42 post-ERCP. Based on ultrasonographic results, four groups differing in thyroid morphology were distinguished. The data show that an average amount of only 4.7 g of enterally applied iodine is associated with a lasting decrease of TSH, especially in patients with enlarged organs with nodular transformation. As far as TT3 is concerned, there was a significant increase in all patient groups; regarding FT4 we only observed a marked increase in the group with enlarged, nodular thyroid glands. There was a notable increase in urinary iodine excretion on day 21, and a further increase on day 42 post-ERCP. Clinical symptoms of hyperthyroidism did not occur. We conclude that before administration of iodine-containing contrast agent for ERCP in patients without a history of thyroid disease, thyroid ultrasonographic examination, rather than TSH measurements, should be performed, in order to identify patients already at risk for hyperthyroidism before diagnostic enteral contrast-medium application.

The Hyperthyroid Fetus and Infant

After completing this article, readers should be able to: 1. Describe the etiology of transient and persistent neonatal hyperthyroidism. 2. Delineate the diagnostic tests for thyroid-stimulating hormone receptor antibodies. 3. Develop a treatment plan for fetal and neonatal hyperthyroidism and a management plan for subsequent pregnancies. 4. Provide guidelines for breastfeeding when the mother is receiving antithyroid medications. 5. Describe the long-term risks of neonatal hyperthyroidism. The first clinical description of neonatal hyperthyroidism was published in 1912, and the discovery of the transplacental passage of thyroid-stimulating immunoglobulins (TSI) provided an understanding for the etiology of this condition in 1964. There were, however, a few cases of persistent neonatal hyperthyroidism, initially described in 1976, that were inconsistent with the transient clinical course expected with a maternally acquired antibody. The etiology of persistent neonatal hyperthyroidism was clarified by the discovery of an activating germ-line mutation in the thyroid-stimulating hormone (TSH) receptor in 1995. When a mother has autoimmune thyroid disease, fetal and neonatal hyperthyroidism result from transplacental passage of TSI. The mother usually has a history of hyperthyroidism, but neonatal hyperthyroidism also has been reported in mothers who have hypothyroidism due to Hashimoto thyroiditis. The clinical status of the mother does not determine the infant’s risk for hyperthyroidism. The mother may have been treated with 131I or a subtotal thyroidectomy in the past and may be euthyroid or she may be receiving thyroid replacement therapy at the time of her pregnancy, but she still can be producing high titers of TSI. In a review of neonatal hyperthyroidism, mothers were clinically hyperthyroid during pregnancy in only 18 of 38 cases (47%). The prevalence of clinical hyperthyroidism in pregnancy has been reported to be 0.1% to 0.4% and is the most common endocrine disorder during pregnancy after diabetes. Clinical fetal and neonatal hyperthyroidism has been reported to occur …

The incidence of hyperthyroidism in Austria from 1987 to 1995 before and after an increase in salt iodization in 1990.

Between 1963 and 1990, Austria had iodized salt prophylaxis of endemic goitre with 10 mg KI (7.5 mg I) per kg. This was obviously insufficient, as urinary iodine excretion ranged from 42 to 78 microg I per g of creatinine and goitre in adults remained in the endemic range of 15%-30%. Therefore salt iodization was doubled in 1990. The aim of this study was to assess the annual incidence of different types of hyperthyroidism (HT) before and after this increase in salt iodization. The incidence of HT was recorded in 14 nuclear medicine centres from 1987 to 1995. In five additional centres data were available from 1992 onwards. Data prior to 1992 were documented retrospectively, while those after 1992 were recorded prospectively. The 14 centres drew patients from an area with a population of approximately 4.23 million while all 19 institutes were estimated to cover an area with a population of 5.4 million (the total population of Austria is 7.86 million). A total of 414232 persons were examined for the first time in the participating centres. HT and the type of HT were defined by clinical examination, serum TSH, thyroid hormone levels in blood, ultrasonography, scintigraphy and serum autoantibody titres. HT was classified into immunogenic HT (Graves' or Basedow's disease, GD) and HT with intrinsic thyroid autonomy (uni-, multinodular or disseminated Plummers' disease, PD). HT was also divided into overt (o) or subclinical (sc) disease. The following data were calculated: annual incidence per 100000 and the relative risk (RR) for HT with 95% confidence intervals (CI). In addition, linear trends were calculated for each type of HT by means of logistic regressions. In the 19 centres a total of 47834 patients with HT were registered from 1987 to 1995. PD accounted for 75% of all cases of HT and GD for 19%, while other types of HT were present in 6%. From 1987 to 1989 (time period T0), the annual incidence of oPD was 30.5 (95% CI 29.6-31.5) per 100000. The RR compared to the baseline period T0 was highest in 1992 (1.37; 1.3-1.45) and decreased to 1.17 (1.1-1.24) in 1995. The annual incidence of scPD in T0 was 27.4 (26.5-28.3) per 100000. The RR was highest in 1991 (1.64; 1.56-1.73) and was 1.60 (1. 51-1.69) in 1995. In oPD and scPD a higher RR was observed in persons older than 50 years of age, particularly in men. The incidence of oGD in T0 was 10.4 (9.8-10.9) per 100000; the maximum RR increased to 2.19 (2.01-2.38) in 1993 and decreased to 1.95 (1.78-2.13) in 1995. The incidence of scGD was 1.9 (1.6-2.1) in T0. The maximum RR was observed in 1994 (2.47; 2.04-3.0) and it was still 2.26 (1.85-2.77) in 1995. The increased incidence of oGD and scGD was evenly distributed in all ages and both sexes. The time course of different types of HT following the increase in salt iodization could be divided into two phases: an increase in the incidences of HT with peaks after 1-4 years and a subsequent decrease, the only exception being scGD. The effect was more pronounced in GD than in PD. PD showed an age and gender dependency over time, while GD did not.

Late effects of ionizing radiations on the thyroid gland

The thyroid is the purest endocrine gland in the body and is likely to produce clinically significant abnormalities after external radiotherapy. Functional clinical modifications after direct irradiation exceeding 30 Gy are essentially related to hypothyroidism which may be clinically overt or subclinical with normal serum free thyroxine levels and high thyrotropin concentrations; the risk of hyperthyroidism, silent thyroiditis and Hashimoto's disease is also increased. Secondary hypothyroidism related to irradiation of the hypothalamus and the pituitary gland may arise with doses over 40-50 Gy following treatment for brain and nasopharyngeal tumors--Morphological glandular modifications induced by radiotherapy are responsible for the appearance of benign adenomas, more rarely cystic degenerations and specially well differentiated papillary or follicular carcinomas among children and adults. After irradiation during childhood for benign or malignant tumors, thyroid cancers are more frequent, higher for younger children, and the relative excess risk is increased from 15.6-to 53-fold; tumors can belatedly occur, more than 35 years after initial therapy. Thereby, in order to limit excess morbidity, it is evident that long term supervision with careful clinical and biological evaluations is necessary for patients who previously received neck, upper mediastinum and pituitary radiation therapy.

The risk of hyperthyroidism following an increase in the supply of iodine

The risk of hyperthyroidism following an increase in the supply of iodine