Urinary iodine concentrations Examination Surveys

Caldwell, K. L., Jones, R., Hollowell, J. G. (2005). Urinary iodine concentration United States National Health and Nutrition Examination Survey 2001—2002. Thyroid. 15 692—699. 

Notes-. The urinary iodine concentration of Tasmanian schoolchildren in the 2000-2001 pre-intervention survey is investigated using frequency of consumption of milk drinks and yoghurt. To determine whether more frequent intake of these iodine-containing foods are associated with higher levels of adequate iodine nutrition, the percentage, number and ratio of children with a urinary iodine concentrations of at least 100 j,g/l are examined. 

A six year national survey of urinary iodine cietion in the U.S. is currently und way in our laboratory, as part of the National Health and Nutrition Examination Survey m. A final repot will be available in ap[ x)ximately three years. Data, which is not part of this national survey, collected fix>m 1990 to 1992 in our laboratory, reveals a mean urinary iodine exCTetion of 165 pg/lita (n = 263) which appears to be somewhat Iowa than values rqxnted between 1973 and 1985 The urinary iodine concentration was detennined by the Benotti et al. modificaticMi of the traditional method of Sandell and Koltoff, which is based on the reduction of ferric sulfate by arsenious acid after digesting the urine sample with chloric acid. 

Recent studies from the US reported that all urine samples obtained from 2820 US residents in the National Health and Nutrition Examination Survey (2001—2002) contained perchlorate with a median value of 3.6 o,g/l (Blount et al., 2006a, b), and that in women, but not in men, with a urinary iodine <100 j,g/l, there was an inverse correlation of urine perchlorate with serum T4 values and a direct correlation with serum TSH values (Blount et al., 2006a, b). However, we have recently assessed urine perchlorate concentrations in 398 first-trimester pregnant women, residing in Wales and Italy, with a median value of 2.7 xg/l and low urine iodine values <100 j,g/l, and found no correlation between urine perchlorate and serum free T4 and TSH concentrations (Pearce et al., 2007a). Further studies are underway to obtain more information on this obviously important public health issue. 

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