Endocrinology is a branch of medicine and biology that is concerned with the diseases and conditions of the endocrine system and the hormones associated with it. Metabolism refers to the life-sustaining chemical reactions occurring in the living organism. Since most organisms live under constantly changing environments, metabolic reactions should be finely regulated to maintain homeostasis. This metabolic regulation further allows organisms to interact actively with the environment and respond to signals. Metabolic regulation occurs extrinsically or intrinsically. In extrinsic control, cells respond to signals from other cells, transmitted in the form of hormones, growth factors and other soluble messengers. A good example of this is the endocrine hormone insulin that regulates glucose metabolism. Therefore, any hormonal imbalance in the endocrine system leads to metabolic syndromes. This book explores all the important aspects of endocrinology and metabolism. It provides significant information of these disciplines to help develop a good understanding of associated endocrine and metabolic disorders. Those in search of information to further their knowledge will be greatly assisted by this book.