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?