Preface

Thyroid disorders are common endocrinal problems more common in women. This book presents various aspects of thyroid disorders as seen in clinical practice. Book will be useful for clinicians, medical students and nursing staff. The purpose of the book is to disseminate knowledge on thyroid diseases. The book contains articles on congenital hypothyroidism, radio diagnostic techniques, thyroid carcinoma and preservation of parathyroid gland and during surgical resection of thyroid gland.

I would like to thank all the contributing authors for their cooperation in submitting their articles in time. I am also grateful to Kristina Kardum, Author Service Manager for her time to time guidance and cooperation.

> **Dr. P.G. Raman** MD, FRCP (Edin) Ex-Professor of Medicine M.G.M. Medical College, DAVV, lndore (M.P.), India

**Chapter 1**

**Provisional chapter**

**Introductory Chapter: Introduction to Thyroid**

**Introductory Chapter: Introduction to Thyroid** 

DOI: 10.5772/intechopen.82044

Thyroid disorders are most common endocrine problem next to diabetes mellitus. Thyroid disorders affect women more compared to men. Thyroid glands secrete, store, and release triiodothyronine (T3) and thyroxine (T4). The hormone T4 gets converted into T3 at tissue level and produces its effect. Iodine is necessary for production of thyroid hormone. Iodine in food is trapped by thyroid gland and is utilized in hormone production. Pituitary and hypothalamus control thyroid gland hormone secretion. TRH from hypothalamus modulates through pituitary to produce TSH, which in turn controls thyroid hormone production. If T4 and T3 are low, TSH level increases to stimulate thyroid gland to secrete more hormone. T3 and T4 hormones have profound effect on the body. Almost all the tissues are stimulated, and body metabolism is increased. T3 and T4 affect cardiovascular system, GI tract, brain, metabolism, weight, bone, etc. With increased T4 and T3, there is tachycardia, diarrhea, hyperglycemia, lowering of cholesterol, increased growth rate in infant, normal brain development, and sexual function. Undiagnosed hypothyroidism in infants not only affects physical and bony

growth but also damages brain growth. If untreated, it leads to permanent damage.

Thyroid functions are affected by congenital absence of thyroid glands, autoimmune thyroid disease, surgical removal, infiltrative diseases, and after radiation to neck. Drugs like amiodarone, lithium, interferon alpha, and interleukin 2 prevent thyroid glands from making

Pituitary damage by tumor radiation or surgery can affect thyroid glands and cause second-

For brain maturation and brain function, thyroid hormone is necessary. Thyroid diseases like hypothyroid can cause lethargy, hyporeflexia, depression, memory impairment, weight gain, dry

> © 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

distribution, and reproduction in any medium, provided the original work is properly cited.

**Disorders**

**Disorders**

Poondy Gopalratnam Raman

Poondy Gopalratnam Raman

http://dx.doi.org/10.5772/intechopen.82044

**1. Physiological considerations**

hormone and causing hypothyroidism.

ary hypothyroidism.

Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

#### **Introductory Chapter: Introduction to Thyroid Disorders Introductory Chapter: Introduction to Thyroid Disorders**

DOI: 10.5772/intechopen.82044
