Book excerpt: For more than 65 years, Williams Textbook of Endocrinology has been the gold standard in the field, delivering authoritative guidance on every aspect of adult and pediatric endocrine system disorders. The 13th Edition has been thoroughly updated by Drs. Shlomo Melmed, Kenneth S. Polonsky, P. Reed Larsen, and Henry M. Kronenberg, to bring you state-of-the-art coverage of diabetes, metabolic syndrome, obesity, thyroid disease, testicular disorders, and much more, all designed to help you provide optimal care to every patient. Bridging the gap between basic science and clinical information, it is an essential, relevant resource for endocrinologists, endocrine surgeons, gynecologists, internists, and pediatricians – any clinician who needs the most reliable coverage available on the diverse features across the spectrum of endocrine disease. Obtain a better understanding of both scientific insight and clinical data from the classic reference that delivers the current information you need in a highly illustrated, user-friendly format. Stay up to date with expanded discussions of autoimmune thyroid diseases, mechanisms, and the appropriate treatment of the ophthalmopathy of Graves’ disease; a new section on the interpretation of fine needle aspiration results in patients with thyroid nodules; and new coverage of when and when not to use radioiodine in the treatment of patients with thyroid cancer. Update your knowledge and skills with all-new chapters on Genetics of Endocrine Disease, Endocrinology of Population Health, and Laboratory Techniques for Recognition of Endocrine Disorders. Confidently manage any clinical endocrinopathy you may encounter thanks to new information on recent FDA-approved drugs for pituitary disorders, a new focus on pediatrics, and new content on diabetes, obesity, and appetite control. Benefit from the expertise of dynamic new contributors who offer fresh perspectives throughout.