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Adiation and Breast Feeding

Question I have a patient with papillary thyroid cancer with nodal metastasis. She was diagnosed when she was pregnant at 2 months. One month postpartum, she underwent total thyroidectomy, and is being evaluted for radioblation with suppressive therapy. She is currently breast feeding, and intends to breast feed her now 2 months old child. How […]

Graves’ Disease and the Manifestations of Thyrotoxicosis

ABSTRACT   Graves’ disease (GD) is an autoimmune disorder characterized by hyperthyroidism and various systemic manifestations, including thyroid eye disease (TED) and, less commonly, dermopathy. This chapter provides an in-depth review of GD, covering its history, epidemiology, risk factors, and the molecular mechanisms underlying autoimmune hyperthyroidism. Emphasis is placed on emerging insights into the genetic, […]

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ABSTRACT   Thyroid cancer is the second most common malignancy to co-occur in pregnancy. Further, the rising prevalence of treated thyroid cancer in women of child-bearing age means that survivors of thyroid cancer are frequently presenting for obstetric care, occasionally in the setting of persisting structural disease. To ensure that optimal health outcomes are achieved […]

Impaired Sensitivity to Thyroid Hormone: Defects of Transport, Metabolism and Action

ABSTRACT   Resistance to thyroid hormone (RTH), a syndrome of reduced responsiveness of target tissues to thyroid hormone (TH) was identified in 1967 (1). An early report proposed various mechanisms including defects in TH transport, metabolism and action (2). However, with the identification of TH receptor beta (THRB) gene mutations in 1989 (3, 4), the […]

Thyroid Hormone Serum Transport Proteins

ABSTRACT   Thyroid hormone (TH) effects are dependent on the quantity of the hormone that reaches the tissues, hormone activation, and the availability of unaltered TH receptors in the cell’s nuclei and cytoplasm. Since TH enters the cell unbound, the concentration of free rather than total hormone reflects more accurately the activity level of TH-dependent […]

Thyrotropin-Secreting Pituitary Adenomas

ABSTRACT Thyrotropin-secreting pituitary tumors (TSH-omas) are a rare cause of hyperthyroidism and account for less than 1% of all pituitary adenomas. It is, however, noteworthy that the number of reported cases increased over the last few years because of the routine use of ultrasensitive immunometric assays for measuring TSH levels. Contrary to previous RIAs, ultrasensitive […]

Thyroid Nodules and Thyroid Cancer Prior to, During, and Following Pregnancy

ABSTRACT   Thyroid cancer is the second most common malignancy to co-occur in pregnancy. Further, the rising prevalence of treated thyroid cancer in women of child-bearing age means that survivors of thyroid cancer are frequently presenting for obstetric care, occasionally in the setting of persisting structural disease. To ensure that optimal health outcomes are achieved […]

Thyroid Hormones in Brain Development and Function

ABSTRACT   Thyroid hormones are essential for normal brain development. They influence neurogenesis, neuronal and glial cell differentiation and migration, synaptogenesis, and myelination. Thyroid hormone deficiency may severely affect the brain during fetal and postnatal development, causing retarded maturation, intellectual deficits, and neurological impairment. Neural cells express the thyroid hormone nuclear receptors THRA and THRB, […]

PHYSIOLOGY OF THE HYPOTHALAMIC-PITUITARY-THYROID AXIS

ABSTRACT   The activity of the thyroid gland is predominantly regulated by the concentration of the pituitary glycoprotein hormone, thyroid-stimulating hormone (TSH). In the absence of the pituitary or of thyrotroph function, hypothyroidism ensues. Thus, regulation of thyroid function in normal individuals is to a large extent determined by the factors which regulate the synthesis […]

Clinical Strategies in the Testing of Thyroid Function

ABSTRACT   In the past decades, emphasis has shifted from testing thyroid function in individuals who are likely to have clinically overt thyroid disorders to a broader population, an approach that includes also identification of so-called subclinical or mild thyroid dysfunctions. The key measurement methods used to detect thyroid dysfunction are still serum thyroid stimulating […]

Cellular Action of Thyroid Hormone

ABSTRACT Thyroid hormones (THs) regulate growth, development, metabolism. This chapter aims to provide a comprehensive overview of the molecular and cellular mechanism(s) for intracellular signaling by TH. At the cellular level, THs bind to thyroid hormone receptors (TRs) that are members of the nuclear hormone receptor family.  TRs act as ligand-activated transcription factors that bind […]

The Iodine Deficiency Disorders

ABSTRACT This chapter provides an overview of the disorders caused by iodine deficiency. Extensively referenced, it includes data on dietary sources of iodine, goitrogens, the effects of iodine deficiency throughout the lifecycle, the pathophysiology of iodine deficiency, as well as strategies for control and monitoring of the iodine deficiency disorders, such as iodized salt and […]

Genetic Defects in Thyroid Hormone Supply

  ABSTRACT Congenital hypothyroidism (CH) is the most frequent endocrine-metabolic disease in infancy, with an incidence of about 1/2500 newborns [1, 2]. In the last 20-30 years the incidence of congenital hypothyroidism in newborns has increased from 1:4000 to 1:2000 [3, 4]. This phenomenon could be explained by using a lower b-TSH cutoff, that allowed […]

TSH Receptor Mutations and Diseases

ABSTRACT The thyroid-stimulating hormone (TSH) receptor (TSHR) is a member of the glycoprotein hormone receptors (GPHRs), a sub-group of class A G protein-coupled receptors (GPCRs). TSHR and its ligand thyrotropin are of essential importance for growth and function of the thyroid gland. The TSHR activates different G-protein subtypes and signaling pathways, of which Gs and […]

Disorders of the Thyroid Gland in Infancy, Childhood and Adolescence

This chapter is, in part, based on the previous version written by Prof. Rosalind Brown. ABSTRACT Thyroid disorders in infancy, childhood and adolescence represent common and usually treatable endocrine disorders. Thyroid hormones are essential for normal development and growth of many target tissues, including the brain and the skeleton. Thyroid hormone action on critical genes […]

Metabolism of Thyroid Hormone

    ABSTRACT Thyroid hormone is indispensable for normal development and metabolism of most cells and tissues. Thyroid hormones are metabolized by different pathways: glucuronidation, sulfation, and deiodination, the latter being the most important. Three enzymes catalyzing deiodination have been identified, called type 1 (D1), type 2 (D2) and type 3 (D3) iodothyronine deiodinases. D1 […]

Diagnosis and Treatment of Graves’ Disease

   ABSTRACT Diagnosis of the classic form of Graves’ disease is easy and depends on the recognition of the cardinal features of the disease and confirmation by tests such as TSH and FTI. The differential diagnosis includes other types of thyrotoxicosis, such as that occurring in a nodular gland, accompanying certain tumors of the thyroid, […]

Effects of the Environment, Chemicals and Drugs on Thyroid Function

ABSTRACT The sensitive and tightly regulated feedback control system, thyroid gland autoregulation, and the large intrathyroidal and extrathyroidal storage pools of thyroid hormone serve to provide a constant supply of thyroid hormone to peripheral tissues in the face of perturbations imposed by the external environment, chemicals and drugs, and a variety of diseases processes. The […]

Multinodular Goiter

ABSTRACT Multinodular goiter (MNG) is the most common of all the disorders of the thyroid gland. MNG is the result of the genetic heterogeneity of follicular cells and apparent acquisition of new cellular qualities that become inheritable. Nodular goiter is most often detected simply as a mass in the neck, but sometimes an enlarging gland […]

Thyroid Regulation and Dysfunction in the Pregnant Patient

ABSTRACT Thyroid disease in pregnancy is a common clinical problem. During the past 2 years significant clinical and scientific advances have occurred in the field. This chapter reviews the physiology of thyroid and pregnancy focusing on iodine requirements and advances in placental function. There follows discussion on thyroid function tests in pregnancy and their interpretation […]

Cellular Uptake of Thyroid Hormones

ABSTRACT The biological activity of thyroid hormone (TH) is regulated at the target tissue level by two important processes, i.e. deiodination and plasma membrane transport. The first process involves the expression of the deiodinase D2, which converts the prohormone T4 to bioactive T3, and/or of the deiodinase D3 which converts both T4 and T3 to […]

Autoimmunity to the Thyroid Gland

ABSTRACT This discussion stresses the normal occurrence of immune self-reactivity, the genetic and environmental forces that may amplify such responses, the role of the antigen-driven immune attack, secondary disease-enhancing factors, and the important contributory role of antigen-independent immune reactivity. Research on thyroid autoimmunity has benefited greatly by knowledge of the specific target antigens and easy […]

Chapter 2 Thyroid Hormone Synthesis And Secretion

ABSTRACT The main function of the thyroid gland is to make hormones, T4 and T3, which are essential for the regulation of metabolic processes throughout the body. As at any factory, effective production depends on three key components – adequate raw material, efficient machinery, and appropriate controls. Iodine is the critical raw material, because 65% […]

Ontogeny, Anatomy, Metabolism and Physiology of the Thyroid

ABSTRACT This chapter presents an analysis and a summarized  synthesis of  our present  knowledge  of  the  biology  of  the thyroid gland, phylogeny ,ontogeny ,anatomy ,structure ,general metabolism ,regulatory factors  and  hormones , signalling cascades  and  their regulations , ( eg  TSH ), functions including iodine metabolism  and  thyroid  hormones  synthesis , control  of  gene expression ,differentiation  […]

The Non-Thyroidal Illness Syndrome

  ABSTRACT NTIS refers to a syndrome found in seriously ill or starving patients with low fT3, usually elevated RT3, normal  or low TSH, and if prolonged, low fT4. It is found  in a high proportion of patients in the ICU setting, and correlates with a poor prognosis if TT4 is <4ug/dl. The patho-physiology includes […]