Thyroid diseases are those that affect the function of the thyroid gland. This gland is butterfly-shaped and is located towards the front of the neck. It produces hormones that flow into the bloodstream and play an essential role in regulating metabolism, heart rate, body temperature, food movement through the digestive tract, brain development, etc. Thyroid disorders are divided into many categories, such as, hypothyroidism, hyperthyroidism, structural abnormalities such as goiter and tumors. Tiredness, muscle cramps, constipation, weight loss, and slow heart rate are a few symptoms of hypothyroidism whereas hyperthyroidism is symptomatized by insomnia, fast heart rate, weight gain, anxiety, tremors, excess sweating, etc. This book unfolds the most recent researches related to thyroid diseases. From theories to research to practical applications, case studies related to all contemporary topics of relevance to these disorders have been included herein. This book will serve as a useful resource for experts as well as students.