"Frontiers In Thyroidology" assembles the prize lectures, symposia, and papers presented during the Ninth International Thyroid Congress in Sao Paulo, Brazil in September, 1985. This book represents the State-of the-Art in thyroid studies with its continuous expansion into the areas of immunology, molecular biology, clinical and environmental medicine. As its name also indicates, the material compiled in this volume defines important questions to be answered in basic and applied aspects of the thyroid. So, this book clearly demonstrates the rewards, excitement, and challenges posed by the thyroid gland. Once again, the thyroid gland, through its unique and important functions and implications in health and disease, has been able to congregate scientists throughout the world to communicate their findings, to share their expertise and experiences, and to strengthen their bonds of friendship and commitment to make a better world through their work. This publication consists of 309 papers in 19 different topics. The prize lectures and symposia review and update our knowledge in basic and clinical aspects of exceptional interest in the thyroid field. "Frontiers in Thyroidology" adds to a series of publications from previous interna tional thyroid meetings which includes: "Advances in Thyroid Research", London, 1960; "Current Topics in Thyroid Research", Rome, 1965; "Further Advances in Thyroid Research", Vienna, 1970; "Thyroid Research", Boston, 1975, and "Thyroid Research VIII", Sydney, 1980. We would like to express our gratitude to Mrs. P. Langford and Drs.