RT Journal Article SR Electronic T1 Aetiology of hyperthyroidism in Canada and Wales. JF Journal of Epidemiology and Community Health JO J Epidemiol Community Health FD BMJ Publishing Group Ltd SP 245 OP 248 DO 10.1136/jech.37.3.245 VO 37 IS 3 A1 Williams, I A1 Ankrett, V O A1 Lazarus, J H A1 Volpe, R YR 1983 UL http://jech.bmj.com/content/37/3/245.abstract AB A retrospective, comparative review of 100 consecutive new outpatients presenting with hyperthyroidism in Cardiff, South Wales, and in Toronto, Canada, was performed. The aim was to quantify the causes of hyperthyroidism with particular emphasis on the prevalence of viral thyroiditis and "silent" thyroiditis. The proportional morbidity of Graves' disease (approximately 70%) was similar in the two groups. Toxic multinodular goitre and toxic adenoma (Plummers' disease) occurred significantly more frequently in Cardiff (25% v 8%), whereas thyroiditis predominated in Toronto (17% v 1%).