This book is for patients with thyroid diseases and anyone interested in the thyroid, including carers of thyroid patients, members of the lay public and healthcare workers who deal with thyroid patients. The intention is to provide the means by which good quality information about the thyroid gland and its diseases can be found, accessed, weighed and judged for scientific merit. The book can be read like a story, but can also serve readers as a reference manual when looking for information on a thyroid-related topic. Thyroid diseases affect 10% of the population. People with thyroid problems, their family, carers and health professionals often seek information. The available sources are disappointing and misleading. There is an unmet need and a desire by patients, the lay public, students and early career healthcare workers to learn how to access and appraise the evidence, which is rarely fulfilled by existing resources. The book consists of two parts. Part One contains six chapters.The first Chapter ("Obstacles to seeking the truth") discusses the common hurdles that can come between us and the knowledge we seek. Chapter Two ("Thyroid basics") is an overview of the structure and function of the thyroid gland and the common diseases that affect it, narrated through the convoluted history of discoveries relating to the thyroid. In Chapter Three ("What is the evidence") evidence-based medicine is discussed, how different medical publications are classified, the processes involved in publishing medical papers and how they are structured. This is relevant and important in understanding the selection process in play that a piece of academic work is subjected to before it reaches its readers, how it varies and how it may correlate with the quality of the end product. Chapter Four ('Mining the truth') is about conducting searches. It identifies appropriate search engines and gives tips on how to stay on course. Chapter Five ("Appraising the evidence") outlines how to judge the quality of published papers based on checklists. Chapter Six ("Interpreting the evidence") will help extract the meaning of a piece of research. Part Two ("What is the optimal range?") is an example of a common question asked by patients with hypothyroidism (the commonest thyroid condition). It will reveal a truth that should be making headlines and attracting the attention of patient advocates, thyroid specialists, their professional organisations and the public at large. Yet all relevant parties seem to choose to ignore it and channel their energies in other directions. It is an example of good science yielding valuable knowledge, which is undermined and made worthless by poor implementation. Herein lies the most important message of this book: seeking truth and getting close to it is not enough, how it is used to change the lives of patients is what really matters. Relevant references are included at the end of each chapter to indicate the sources in case the reader wishes to access them.