Goitre prevalence and thyroid abnormalities at ultrasonography: a comparative epidemiological study in two regions with slightly different iodine status. Clin Endocrinol (Oxf

Summary OBJECTIVE The association between severe iodine de®ciency and endemic goitre is well established, but little information is available on the relation between milder degrees of iodine de®ciency and goitre prevalence. SUBJECTS In a comparative epidemiological study performed in two regions in Denmark, we examined 4649 subjects from the general population, women aged 18±65 years and men aged 60±65 years. METHODS Ultrasonography and palpation of the thyroid was performed in all participants. Iodine excretion was measured in casual urine samples. Previous thyroid disease was detected by questionnaires, personal interviews and tracing of records. RESULTS The median iodine excretion was 61 mg/l (mild iodine de®ciency (ID)) and 45 mg/l (moderate ID) in the two regions. Median thyroid volume at ultrasonography was 11´9 ml (mild ID) and 13´6 ml (moderate ID), P < 0´001, and thyroid enlargement was found in 15´0% (mild ID) and 22´6% (moderate ID), P < 0´001. Goitre prevalence increased in both regions with age to the age group 40±45 years, but not after that age. Subjects who had moved from the moderate ID to the mild ID area had the same prevalence of thyroid enlargement as the subjects staying permanently in the mild ID area. Thyroid nodules at ultrasonography were found in 30% in both regions, but nodules were larger and more often palpable in the moderate ID area. Palpable goitre was found in 9´8% (mild ID) and 14´6% (moderate ID), P < 0´001. The greatest regional difference in thyroid abnormalities was found among men. CONCLUSION Marked differences in the prevalence of thyroid abnormalities were found in these regions with modest differences in iodine excretion. It has been known since the beginning of the 19th century that severe iodine de®ciency leads to endemic goitre. Little is known, however, about the relation between iodine intake and thyroid abnormalities in the spectrum between clear iodine de®ciency and iodine repletion. Thyroid volume and goitre prevalence Thus, the minimal iodine intake of a population that will prevent iodine de®ciency disorders remains to be established. This is still a matter of concern, as iodine de®ciency disorders are abundant in many parts of the world including parts of Europe, and several reports have been published on side-effects of iodination programmes We designed a comparative population study of goitre prevalence and thyroid abnormalities at ultrasonography in two regions in Denmark with presumed longstanding mild and moderate iodine de®cienc