Urinary iodine concentrations in swiss schoolchildren from the Zurich area and the Engadine valley.
Zimmermann MB., Hess S., Zeder C., Hurrell RF.
To prevent iodine deficiency disorders in Switzerland, table salt is currently fortified at 15 mg iodide/kg salt. However, several recent reports have suggested that urinary iodine excretion is marginal or inadequate among segments of the Swiss population, including schoolchildren. There is concern that iodine intake in Switzerland may be approaching levels associated with signs of clinical deficiency. Previous studies measuring urinary iodine in Swiss children have encompassed only a limited geographic area in central Switzerland. We have now evaluated urinary iodine concentrations in 243 schoolchildren aged 5 to 13 years from the Zurich area and the Engadine valley. The mean urinary iodine for all children was 11.3 +/- 8.7 micrograms/dl. There was no significant difference between iodine levels in urine from children in the Engadine and those from around Zurich. There were also no significant gender differences in urinary iodine concentrations. The median urinary iodine concentration for all children was 9.6 micrograms/dl, below the threshold suggested by the World Health Organization (< 10 micrograms/dl) as indicative of mild iodine deficiency. 54.3% of the children had urinary iodine concentrations < 10 micrograms/dl and 11.5% had levels < 5 micrograms/dl. The results of this study suggest that the iodine status of some Swiss schoolchildren may no longer be adequate. They indicate the importance of intermittent monitoring of iodine status in Switzerland, where dietary habits and food supply patterns are changing. They also support the recent decision (February 1998) by the Swiss Federal Department of the Interior to increase the concentration of iodide in Swiss table salt, based on the recommendations of the Fluoride-Iodine Commission of the Swiss Academy of Medical Sciences.