Endocrinology studies hormone systems that regulate growth, metabolism, reproduction and homeostasis across the lifespan. This textbook explains endocrine physiology, diagnostic strategies and the clinical management of common disorders: diabetes, thyroid disease, adrenal dysfunction, pituitary disorders and metabolic bone disease. Emphasis is placed on integrating laboratory interpretation with clinical context and individualized treatment planning. Chapters cover endocrine emergencies, hormone replacement principles and the endocrine effects of systemic disease and medications. Practical algorithms for investigation and follow-up help clinicians apply guidelines at the bedside. The book is aimed at medical students, residents and endocrinology trainees seeking a comprehensive clinical reference.