Adequate iodine nutrition in Sweden: a cross-sectional national study of urinary iodine concentration in school-age children

Abstract

Background/objectives: Sweden has a long-standing salt iodization program; however, its effects on iodine intake have never been monitored on a national level. The objective of this study was to evaluate iodine nutrition in the Swedish population by measuring the urinary iodine concentration (UIC) in a national sample of Swedish school-age (6-12 years of age) children.

Subjects/methods: A stratified probability proportionate to size cluster sampling method was used to obtain a representative national sample of school-age children from 30 clusters. Spot urine samples were collected for UIC analysis using a modified Sandell-Kolthoff method.

Results: The median UIC of the children (n=857) was 125 microg/l (range 11-757 microg/l). The proportion of children with a UIC <100 microg/l was 30.0% and the proportion of children with a UIC <50 and >300 microg/l was 5.5 and 3.0%, respectively.

Conclusions: The iodine nutritional status of the Swedish population is adequate. Iodized table salt remains the main dietary source of iodine in Swedish diet. Recommendations to reduce total salt intake in the population urge increased use of iodized salt in the production of processed foods. Pregnant and lactating women with high iodine requirements may still be at risk for low iodine intake. This study will serve as the basis for future monitoring of iodine nutritional status in Sweden.