The epidemiology of thyroid disease.

INTRODUCTION: Thyroid disorders are prevalent and their manifestations are determined by the dietary iodine availability. SOURCES OF DATA: Data from screening large population samples from USA and Europe. AREAS OF AGREEMENT: The most common cause of thyroid disorders worldwide is iodine deficiency, leading to goitre formation and hypothyroidism. In iodine-replete areas, most persons with thyroid disorders have autoimmune disease. AREAS OF CONTROVERSY: Definition of thyroid disorders, selection criteria used, influence of age and sex, environmental factors and the different techniques used for assessment of thyroid function. GROWING POINTS: Increasing incidence of well-differentiated thyroid cancer. Environmental iodine influences the epidemiology of non-malignant thyroid disease. AREAS TIMELY FOR DEVELOPING RESEARCH: Iodine supplementation of populations with mild-to-moderate iodine deficiency. An evidence-based strategy for the risk stratification, treatment and follow-up of benign nodular thyroid disease. Is there any benefit in screening adults for thyroid dysfunction?