Diagnosis and treatment of thyrotoxicosis in childhood. A European questionnaire study

A covering letter and a questionnaire covering the diagnosis and treatment of thyrotoxicosis in childhood was circulated between October 1992 and February 1993 amongst 672 European members of the European Thyroid Association (ETA) and members of the European Society for Pediatric Endocrinology (ESPE). Almost 50% replied to the letter and 99 individuals or groups from 22 countries completed the questionnaire. A consensus was reached on the use of total thyroxine (T4) and/or free T4 and thyrotropin as routine diagnostic tools. Two-thirds included total triiodothyronine (T3) and/or free T3 and 32% used a thyrotropin-releasing hormone test. Surprisingly, thyroglobulin autoantibodies were used as a routine test by 78%; 63% included thyrotropin receptor antibodies and 60% microsomal antibodies, whereas only 50% measured thyroperoxidase antibodies. For thyroid imaging, 40% performed a thyroid scintigram and 56% measured the size of the thyroid gland by ultrasound. Antithyroid drugs (ATD) were the basic initial treatment of choice given by 99% of the respondents for children with uncomplicated Graves' disease. Carbimazole, methimazole and thiamazole were the most frequently used drugs, with a median initial dose of 0.8 mg.kg-1.day-1. Two-thirds added beta-blockers and a few used sedatives. The ATD dose was adjusted for each patient by 39%, whereas 56% combined ATD with T4 for long-term treatment; 84% gave treatment for a fixed period (44% for 1-2 years). Surgery was considered the treatment of choice in children with an adenoma (83%), with a nodular (53%) or large goiter (16%) and recurrence after ATD (14%).(ABSTRACT TRUNCATED AT 250 WORDS)     

Screening for congenital hypothyroidism used as an indicator of the degree of iodine deficiency and of its control

Neonatal thyroid screening using serum thyrotropin (TSH) as the primary screening test detects not only permanent sporadic congenital hypothyroidism, whose incidence is about 1 per 4000 births, but also compensated or transient primary hypothyroidism, whose incidence can be as high as 1 in 10 neonates and whose main cause is iodine deficiency. Elevated serum TSH in the neonate indicates insufficient supply of thyroid hormones to the developing brain, and therefore, constitutes the only indicator that allows prediction of possible impairment of mental development at a population level, which is the main consequence of iodine deficiency. Therefore, the World Health Organization (WHO), United Nations International Children's Emergency Fund (UNICEF), and the International Council for Control of Iodine Deficiency Disorders (ICCIDD) included neonatal TSH as one of the indicators for assessing iodine deficiency disorders (IDD) and their control. In the absence of iodine deficiency, the frequency of neonatal TSH above 5 mU/L whole blood (or 10 mU/L serum) is less than 3%. A frequency of 3%-19.9% indicates mild IDD. Frequencies of 20%-39.9% and above 40% indicate moderate and severe IDD, respectively. Neonates exhibit elevated serum TSH more frequently than adults for a similar degree of iodine deficiency. Consequently, they appear hypersensitive to the effects of iodine deficiency. This characteristic is explained by a particularly low iodine content of the thyroid of neonates and, consequently, by an accelerated turnover rate of their intrathyroidal iodine reserves. This turnover rate is 1% in adults. It is 17% in the neonate in conditions of iodine repletion, but is as high as 62% and 125% in conditions of moderate and severe iodine deficiency, respectively. Such an accelerated turnover rate requires thyroid hyperstimulation by TSH that is morphologically evidenced even in moderately iodine deficient neonates. Neonatal screening using primary TSH is implemented in most countries with mild IDD where it detects the cases of sporadic, permanent congenital hypothyroidism and where it is also used as a monitoring tool for IDD evaluation and control. However, the implementation of such programs in countries affected by moderate or severe IDD is still insufficient because of lack of resources of the countries. This should be considered in the framework of the external support often provided to these countries for the implementation of programs of universal salt iodization. Monitoring of these programs in order to achieve the goal of sustainable elimination of IDD now constitutes an absolute priority.     

The disorders induced by iodine deficiency

This paper reviews present knowledge on the etiology, pathophysiology, complications, prevention, and therapy of the disorders induced by iodine deficiency. The recommended dietary allowances of iodine are 100 micrograms/day for adults and adolescents, 60-100 micrograms/day for children aged 1 to 10 years, and 35-40 micrograms/day in infants aged less than 1 year. When the physiological requirements of iodine are not met in a given population, a series of functional and developmental abnormalities occur including thyroid function abnormalities and, when iodine deficiency is severe, endemic goiter and cretinism, endemic mental retardation, decreased fertility rate, increased perinatal death, and infant mortality. These complications, which constitute a hindrance to the development of the affected populations, are grouped under the general heading of iodine deficiency disorders (IDD). At least one billion people are at risk of IDD. Iodine deficiency, therefore, constitutes one of the most common preventable causes of mental deficiency in the world today. Most of the affected populations live in mountainous areas in preindustrialized countries, but 50 to 100 million people are still at risk in Europe. The most important target groups to the effects of iodine deficiency from a public health point of view are pregnant mothers, fetuses, neonates, and young infants because the main complication of IDD, i.e., brain damage resulting in irreversible mental retardation, is the consequence of thyroid failure occurring during pregnancy, fetal, and early postnatal life. The main cause of endemic goiter and cretinism is an insufficient dietary supply of iodine. The additional role of naturally occurring goitrogens has been documented in the case of certain foods (milk, cassava, millet, nuts) and bacterial and chemical water pollutants. The mechanism by which the thyroid gland adapts to an insufficient iodine supply is to increase the trapping of iodide as well as the subsequent steps of the intrathyroidal metabolism of iodine leading to preferential synthesis and secretion of triiodotyronine (T3). They are triggered and maintained by increased secretion of TSH, which is ultimately responsible for the development of goiter. The acceleration of the main steps of iodine kinetics and the degree of hyperstimulation by TSH are much more marked in the pediatric age groups, including neonates, than in adults, and the development of goiter appears as an unfavorable side effect in the process of adaptation to iodine deficiency during growth. The most serious complication of iodine deficiency is endemic cretinism, a syndrome characterized by irreversible mental retardation together with either a predominant neurological syndrome or predominant hypothyroidism, or a combination of both syndromes.(ABSTRACT TRUNCATED AT 400 WORDS)     

Modelling quality variations in commercial Ontario pork production

This study explores the interactions of sensory and nutritional environment with genotype occurring in current commercial pork production in Ontario, Canada, which may interact to result in poor quality meat. The study focussed on identifying factors and signalling mechanisms that contribute to poor meat quality, in order to develop strategies to reduce the incidence of unacceptable product quality. In the first phase of the work reported here, animal behaviour and muscle metabolism studies were related to meat colour, tenderness and water-holding capacity measurements from commercially-produced pigs killed in a commercial packing plant. A partial least squares analysis was used to determine the most important of the principal production variables, peri-mortem biochemical measures and post-mortem carcass condition variables studied, in terms of their influence on water-holding, toughness and colour (L*-value). Variations between producer and kill day at the slaughterhouse were very strong contributors to variability in these three meat quality parameters, followed by pH variations. A second phase of the study is currently underway to characterize patterns of gene expression related to extremes of end-product quality and to reduce quality variations by nutritional and behavioural management strategies.     

Adverse effect of amniofetography on fetal thyroid function

Amniofetography is a valuable tool for the diagnosis of fetal malformations. This technique is being used routinely in pregnancies carrying a high risk of external fetal malformations. There are very few published data concerning the effect of radiopaque dyes, containing large amounts of iodide, on fetal thyroid function. We have performed serial determinations of serum thyrotropin and thyroxine in seven newborn infants to assess the effect of amniofetogrpahy on fetal thyroid function. This work demonstrates that amniofetography induces a transient impairment of fetal thyroid function.     

Synergetic Effect of Discontinuous Carbon Fibers and Graphite Flakes on Thermo-Mechanical Properties of Aluminum Matrix Composites Fabricated by Solid–Liquid Phase Sintering

Metals and Materials International - Aluminum (Al) matrix composite materials reinforced with graphite flakes (GF) and pitch-based carbon fibers (CF) were fabricated by solid–liquid phase...     

Fatty Acid Composition and Oil Yield in Fruits of Five <Emphasis Type="Italic">Arecaceae</Emphasis> Species Grown in Cuba

The present study targeted the whole-fruit oil yield and fatty acid composition from five of the most abundant Arecaceae species grown in Cuba. The oil yields (% dry weight), determined by the Soxhlet extraction technique with hexane, were 25.5, 5.3, 6.9, 5.4, and 6.4% for Roystonea regia, Colpothrinax wrightii, Sabal maritima, Sabal palmetto and Thrinax radiata, respectively. The free fatty acid (FFA) content varied from 2.7 to 6.8%. Fatty acid (FA) profiles of the oils indicated that lauric acid (13.7–44.4%), myristic acid (9.4–22.4%) and palmitic acid (9.2–17.1%) as major saturated FA; whereas oleic acid (9.6–42.7%) and linoleic acid (9.3–17.0%) as major unsaturated FA. R. regia fruit seemed the most promising among Arecaceae grown in Cuba because of its high oil yield and low oil FFA content.     

Standardized evaluation of iodine nutrition in West Africa: the African phase of the thyromobil program

Extensive programs of iodine supplementation by iodated salt have been implemented in Africa during the last decade. The present work evaluated their effectiveness in Benin, Burkina Faso, Mali, and Togo. A van equipped with a sonographic device visited 39 sites in the four countries. The prevalence of goiter was evaluated on the basis of the determination of thyroid volume by ultrasonography in 4,011 randomly selected 6- to 12-year-old schoolchildren of both sexes in the 39 sites. The concentration of urinary iodine was measured in 1,545 of these children. The iodine content of table salt collected at home by the children was measured by test kits in 3,202 salt samples, 415 of which were also analyzed by titration. Based on the results obtained by the kits, 83.7% to 97.9% of the salt samples contained iodine. However, the test kits had a low sensitivity and specificity in comparison with titration. The median urinary iodine was within an acceptable range (100-300 14 g/L) in the four countries, but almost one-third of the values were still below normal. The prevalence of goiter was normal (< 5%) in Benin and Togo, and it was 22.4% and 13.4%, respectively, in Burkina Faso and Mali. These results indicate marked improvement of the status of iodine nutrition in comparison with the situation reported only a few years ago in the same countries, but quality control of the iodine content of salt and monitoring of the iodine status of the populations need to be improved.