Thyroid volumes and urinary iodine in Swiss school children, 17 years after improved prophylaxis of iodine deficiency

Salt iodine content in Switzerland was raised From 7.5 to 15 mg per kg in 1 980, and since then dietary iodine intake has been considered to be suffici ent, even though a slight decrease due to imported food has recently been r eported. The aim of this study was to establish normal values for thyroid v olumes of school children who can be assumed to have had a sufficient iodin e intake all their lifetime, Moreover, the present investigation was undert aken to verify that iodine sufficiency had been achieved equally in two reg ions each served by one of the two Swiss salt producers. Mean iodine concentration in urine spot samples from school children was 16 .1 mu g/dl, and it was identical in both the city of Lausanne (n=215) and t he city of Solothurn (n=208). Thus it can be stated that in both cities (se rved by two different salt producers) iodine intake is equal and sufficient . Accordingly, thyroid volumes measured by ultrasound in school children ag ed 6 to 16 years were the same in both Lausanne (n=202) and Solothurn (n=20 7), Moreover, the age-adjusted median volumes at the 97th percentiles close ly agree with and validate provisional international reference values recen tly proposed by the World Health Organisation and by the International Coun cil for Control of Iodine Deficiency Disease.