Changes in iodine nutrition status in schoolchildren from the Basque Country

An epidemiologic survey showed in 1992 iodine deficiency and endemic goiter in schoolchildren from the Basque Country.

(1) To determine the percentage of homes of schoolchildren where iodized salt (IS) is used; (2) to assess iodine nutrition status in schoolchildren and to compare the data collected to those available from previous epidemiological studies.

A cross-sectional study in 720 randomly selected schoolchildren. Urinary iodine concentration (UIC) was measured using high-performance liquid chromatography(HPLC) with electrochemical detection.

IS was used at 53.0% of the homes (95% confidence interval [CI], 49.2-56.7%). Median UIC has increased by 226%, from 65 μg/L in 1992 to 147 μg/L (percentile [P], P(25), 99 μg/L; P(75), 233 μg/L) today. Both schoolchildren consuming IS and those using unfortified salt at their homes had UICs corresponding to adequate iodine intakes (165 and 132 μg/L respectively). UICs experienced great seasonal fluctuations, being 55% higher during the November-February period than in June-September period (191 μg/L vs 123 μg/L; p<0.001)

Schoolchildren from the Basque Country have normalized their iodine nutrition status. The strong seasonal pattern of UICs suggests that consumption of milk and iodine-rich dairy products coming from cows feed iodized fodder is one of the most significant factors involved in the increase in iodine intake since 1992.