Child Development
Thyroid hormones are major factors for the normal development of the brain. The mechanisms of actions of thyroid hormones in the developing brain are mainly mediated through two ligand-activated thyroid hormone receptor isoforms 50 . It is known that thyroid hormone deficiency may cause severe neurological disorders resulting from the deficit of neuronal cell differentiation and migration, axonal and dendritic outgrowth, myelin formation and synapto-genesis 23 . This is the situation well...
Thyroid Disease in Turner Syndrome
An association between Turner syndrome (TS) and thyroid disease was first suggested by Atria et al. 1 in 1948 when they reported post mortem findings of a small thyroid gland with lymphocytic infiltration in a young woman with Turner syndrome. Many authors reported on a higher prevalence of hypothyroidism and an association with positive thyroid antibodies in TS patients (table 2) 2, 6, 7, 24, 29, 32, 37 . Hypothyroidism is found in up to 35 of TS patients. Thyroid autoimmunity seems to be even...
Diagnostic WorkUp of Congenital Hypothyroidism
A positive newborn screening result calls for immediate diagnostic work-up. Information on maternal medication or morbidity should be obtained to assess the infant's prenatal thyroid status. Clinical examination should be performed to document signs and symptoms of CH and possible associated malformations. There is an increased risk for other congenital anomalies (8.4 ), including cardiovascular, musculoskeletal and CNS malformations 3 . Confirmatory serum measurements of TSH and T4 are...
Hormones Thyroid Agent
1 Weetman AP Autoimmune thyroid disease propagation and progression. Eur J Endocrinol 2003 148 1-9. 2 Dechairo BM, Zabaneh D, Collins J, Brand O, Dawson GJ, Green AP, Mackay I, Franklyn JA, Connell JM, Wass JA, Wiersinga WM, Hegedus L, Brix T, Robinson BG, Hunt PJ, Weetman AP, Carey AH, Gough SC Association of the TSHR gene with Graves' disease the first disease specific locus. Eur J Hum Genet 2005 13 1223-1230. 3 Simmonds MJ, Gough SCL Genetic insights into disease mechanisms of autoimmunity....
Post 131I Cancer Risks
The increased risk of thyroid cancer after thyroid irradiation in childhood has been recognized for nearly 50 years 70 . Thus, a major concern of 131I therapy relates to the risk of thyroid cancer. Detractors of 131I therapy point to the increased rates of thyroid cancer and thyroid nodules observed in young children exposed to radiation from nuclear fallout at Hiroshima or after the Chernobyl nuclear reactor explosion. The thyroid gland is unique in its developmental sensitivity to malignancy...
Iodine Deficiency
When the aforementioned physiological requirements are not met in a given population, a series of functional and developmental abnormalities occur, including thyroid function abnormalities. Iodine deficiency is now accepted as the most common cause of preventable brain damage in the world. According to the World Health Organization (WHO), iodine deficiency disorders (IDD) affect 740 million people throughout the world, and nearly 50 million people suffer from some degree of IDD-related brain...
The Thyroid and Autoimmunity in Children and Adolescents
School of Medicine and Biomedical Science, University of Sheffield, Sheffield, UK Thyroid autoimmunity is the commonest disease process to affect thyroid function. The prevalence of thyroid autoimmunity increases throughout life, with a possible decline in frequency in the very old as a 'healthy survivor' effect. The mere presence of thyroid autoimmunity, as demonstrated by the presence of thyroid autoantibodies or focal thyroiditis, for example, does not equal thyroid disease, since the...
Hypothyroidism in Infancy Childhood and Adolescence
Hypothyroidism during childhood and adolescence can result from a variety of congenital or acquired defects (table 2). Table 3. Symptoms of childhood hypothyroidism Growth and developmental delay Short stature Infantilism in anthropometric ratios Bone age delay Motor developmental delay Skin and hair Pale, coarse, dry and cold skin Hypertricosis in forehead and neck Rare, dry, thick hair Myopathy and muscular pseudohypertrophy Sluggish motor performance, sleepiness, cold intolerance Some...
Iodine Excess
The thyroid gland has intrinsic regulatory mechanisms that maintain normal thyroid function even in the presence of iodine excess. When large amounts of iodine are given to subjects with normal thyroid function a transient decrease in the synthesis of the thyroid hormones occurs for 48 h. This acute inhibitory effect of iodine on thyroid hormone synthesis is called the acute Wolff-Chaikoff effect and is due to increased intrathyroid iodine concentrations. The escape from or adaptation to the...
Nongenomic Actions Extranuclear Actions
A number of T3 effects occur rapidly and are unaffected by inhibitors of transcription and protein synthesis. The site of these actions has been localized to the plasma membrane, cytoplasm and cellular organelles. The nongenomic actions often have a short latency. Cell culture studies suggest that thyroid hormones rapidly, and nongenomically regulate the Ca2 ATPase enzyme, the Na channel via protein kinase C PKC , the K channel via phosphatidyl-inositol 3 PI3 -kinase, the Na H antiporter via...
Pendrins Function in the Thyroid
The exact mechanism by which pendrin functions in the thyroid is still debated. Based on homology with sulfate transporters, it was initially hypothesized that Fig. 4. Structure of the pendrin protein showing 12 transmembrane domains as proposed by Royaux et al. 18 . Circles show some of the more than 100 different mutations identified in patients with Pendred syndrome and DNFB4. The black circles indicate missense and non-sense mutations whereas the gray circles indicate other mutations types...
Antithyroid Drug Therapy
Medical treatment in the first half of the century consisted of bed rest, quinine, and iodine in the form of Lugol's solution 98 . Partial thyroidectomy was used to provide permanent cures 98 . With the advent of thiouracil and propylthiouracil PTU in the mid-1940s, medical therapy of Graves' improved markedly 99 . Because of the relatively high incidence of toxic reactions that developed following the administration of thiouracil including agranulocyto-sis, leukopenia, and drug fever, PTU...
Roussel And Dunn 2004 Thyroid Function
1 Delange F The role of iodine in brain development. Proc Nutr Soc 2000 59 1-5. 2 Hetzel BS, Clugston GA Iodine in Shils M, Olson JA, Shike M, Ross AC eds Nutrition in Health and Disease. Baltimore, Williams amp Wilkins, 1999, vol 9, pp 253-264. 3 Dunn JT What's happening to our iodine J Clin Endocrinol Metab 1998 83 3398-3400. 4 Semba RD, Delange F Iodine in human milk perspectives of infant health. Nutr Rev 2001 59 269-278. 5 Dorea JG Iodine nutrition and breast-feeding. J Trace Elem Med Biol...
Mechanisms of Thyroid Autoimmunity
It is well established that a complex interplay of diverse environmental and genetic susceptibility factors interact in predisposing an individual to autoimmune thyroid disease fig. 1 . Moreover, the contribution that each factor makes varies from patient to patient, and as yet there are no clear genotype-phenotype correlations. We have shown that polymorphisms in the thyroid stimulating hormone receptor TSH-R are associated with Graves' disease but not autoimmune Genetic factors HLA CTLA-4...
References
1 Glinoer D The regulation of thyroid function in pregnancy pathways of endocrine adaptation from physiology to pathology. Endocr Rev 1997 18 404-433. 2 Weetman AP The immunology of pregnancy. Thyroid 1999 9 643-646. 3 Brent GA Maternal thyroid function interpretation of thyroid function tests in pregnancy. Clin Obstet Gynecol 1997 40 3-15. 4 Glinoer D Thyroid Dysfunction in the Pregnant Patient. Available at www.thyroidmanager.org, 2006. 5 Smyth PPA, Hetherton AMT, Smith DF, Radcliffe M...
