The thyroid is an endocrine gland consisting of two lobes which are connected by an isthmus. It produces various hormones that have determining roles in metabolic, cardiovascular, sexual and developmental processes. There are 20,000 protein coding genes of human cells, out of which 70% are expressed in the thyroid itself. The corresponding specific proteins are involved in hormone synthesis. When there is an excessive production of thyroid hormone, it results in a condition known as hyperthyroidism. It causes a number of non-specific syndromes, such as increased appetite, weight loss, tremor, decreased tolerance of heat, muscle weakness, etc. An underactive thyroid gland causes hypothyroidism characterized by symptoms such as abnormal weight gain, heavy menstruation, cold intolerance, hair loss, etc. Nodules in the thyroid gland can cause either cancerous or non-cancerous symptoms. Any of the functional disorders of the thyroid gland can cause the enlargement of the gland and cause goiter. This book is compiled in such a manner, that it will provide in-depth knowledge about thyroid disorders. The topics covered herein deal with the management and treatment of these disorders. The extensive content of this book provides the readers with a thorough understanding of the subject.