Thyroid volumes in a national sample of iodine-sufficient swiss school children: comparison with the World Health Organization/International Council for the control of iodine deficiency disorders normative thyroid volume criteria

The Laboratory for Human Nutrition, Institute of Food Science, Swiss Federal Institute of Technology, Zurich, Switzerland.

OBJECTIVE: The determination of goiter prevalence in children by thyroid ultrasound is an important tool for assessing iodine deficiency disorders. The current World Health Organization/International Council for the Control of Iodine Deficiency Disorders (WHO/ICCIDD) normative values, based on thyroid volume in iodine-sufficient European children, have recently been questioned, as thyroid volumes in iodine-sufficient children from the USA and Malaysia are smaller than the WHO/ICCIDD reference data. Our objective was to describe ultrasonographic thyroid volumes in a representative national sample of iodine-sufficient Swiss school children, and to compare these with the current reference data for thyroid volume. DESIGN AND METHODS: A 3-stage, probability proportionate-to-size cluster sampling method was used to obtain a representative national sample of 600 Swiss children aged 6-12 years. The following data were collected: thyroid size by ultrasound, urinary iodine concentration, weight, height, sex and age. RESULTS: The median urinary iodine concentration (range) of the children was 115 microgram/l (5-413). Application of the WHO/ICCIDD thyroid volume references to the Swiss children resulted in a prevalence of 0%, using either age/sex-specific or body surface area (BSA)/sex-specific cut-off values. Upper limits of normal (97th percentile) of thyroid volume from Swiss children calculated using BSA, sex and age were similar to those reported in iodine-sufficient children in the USA, but were 20-56% lower than the corresponding WHO/ICCIDD references. CONCLUSIONS: Swiss children had smaller thyroids than the European children on which the WHO/ICCIDD references are based, perhaps due to a residual effect of a recent past history of iodine deficiency in many European regions. However, there were sharp differences between our data and a recent set of thyroid volume data in Swiss children produced by the operator and equipment that generated the WHO/ICCIDD reference data. This suggests that interobserver and/or interequipment variability may contribute to the current disagreement on normative values for thyroid size by ultrasound in iodine-sufficient children.

This article has been cited by other articles:

				A. T. Turgut, Z. U. Coskun, E. Ergun, P. Kosar, P. O. Geyik, S. Gorar, and U. Kosar Interobserver and Intraobserver Variability in the Sonographic Measurement of the Size of the Thyroid Gland by Extended Field-of-View Sonography Journal of Diagnostic Medical Sonography, May 1, 2008; 24(3): 147 - 154. [Abstract] [PDF]

				M. B. Zimmermann Assessing Iodine Status and Monitoring Progress of Iodized Salt Programs J. Nutr., July 1, 2004; 134(7): 1673 - 1677. [Abstract] [Full Text]

				M. B Zimmermann, S. Y Hess, L. Molinari, B. de Benoist, F. Delange, L. E Braverman, K. Fujieda, Y. Ito, P. L Jooste, K. Moosa, et al. New reference values for thyroid volume by ultrasound in iodine-sufficient schoolchildren: a World Health Organization/Nutrition for Health and Development Iodine Deficiency Study Group Report Am. J. Clinical Nutrition, February 1, 2004; 79(2): 231 - 237. [Abstract] [Full Text] [PDF]

				K. Guttikonda, J. R. Burgess, K. Hynes, S. Boyages, K. Byth, and V. Parameswaran Recurrent Iodine Deficiency in Tasmania, Australia: A Salutary Lesson in Sustainable Iodine Prophylaxis and Its Monitoring J. Clin. Endocrinol. Metab., June 1, 2002; 87(6): 2809 - 2815. [Abstract] [Full Text] [PDF]