SMALL THYROID VOLUMES AND NORMAL IODINE EXCRETION IN BERLIN SCHOOLCHILDREN INDICATE FULL NORMALIZATION OF IODINE SUPPLY

Iodine deficiency is the major cause of an increase in thyroid gland v olume in infants and children. In this field study we monitored the io dine supply and its effect on the thyroid gland volume in prepubertal and pubertal children in the eastern and western parts of the city of Berlin, so far considered as an area with borderline iodine deficiency . The thyroid gland volume was determined by ultrasound in 1080 (f = 5 52, m = 528) children aged 3-15 years, and was correlated to age, body -surface area and iodine excretion, which was measured in a first-morn ing spot urine. The mean iodine concentration was 115.8 mu g iodine/g creatinine (12.2 mu g iodine/dl urine), with no significant difference s between eastern parts with 114.5 mu g iodine/g creatinine (12.3 mu g iodine/dl urine) vs 116.7 mu g iodine/g creatinine (12.0 mu g iodine/ dl urine) in the western parts of the city. This good iodine supply of the children was surprising compared to former studies in children an d adults. Moreover this normalization of the iodine excretion was refl ected by smaller thyroid gland volumes in the children. The volume was found to increase with age and was 2.4 +/- 1.1 ml in prepubertal (Pra der and Largo: f less than or equal to 10.9 vs. m less than or equal t o 11.5 ys) children, compared to 4.3 +/- 1,7 ml in pubertal children. The goiter prevalence, calculated on this data was below 5%. Among all children there were only 11 (aged 8-13 ys) with abnormal findings of the thyroid gland on ultrasound: 6 with small nodules, 1 girl with a t hyroid-cyst, 2 girls had an inhomogenous echo structure and 2 girls pr esented with a hemithyroidea. This study shows that the iodine supply of the children in Berlin has improved, resulting in smaller sized thy roid glands, compared to those which have been previously published fo r Germany (Muller-Leisse 1988; Klingmuller, 1991; Menken, 1992), but t hey correspond well to volumes described in countries with sufficient iodine supply.