Pediatric endocrinology is a field of medicine that is concerned with the disorders of the endocrine glands. Such disorders manifest as abnormalities in physical growth and sexual development of a child, such as dwarfism and gigantism, intersex, delayed puberty, gonadal dysgenesis, ovarian and testicular dysfunction, etc. Other conditions in children involving disorders of adrenal, pituitary and thyroid glands include underactive or overactive thyroid gland, childhood obesity, multiple endocrine neoplasia, adrenoleukodystrophy, among others. Depending on the condition, pediatric endocrinologists may design treatment modalities involving intensive insulin therapies, radioactive iodine treatment, personalized nutritional evaluation and psychosocial evaluation, parathyroid and thyroid surgeries, etc. This book discusses the fundamentals as well as modern approaches of pediatric endocrinology. It unfolds the clinical aspects of pediatric endocrine disorders, which will be crucial for the progress of this field in the future. In this book, using case studies and examples, constant effort has been made to make the understanding of the difficult concepts of pediatric endocrinology, as easy and informative as possible, for the readers.