title: 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.
abstract: 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.
  
  
  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.
authors.affiliation: The Laboratory for Human Nutrition, Institute of Food Science, Swiss Federal Institute of Technology, Zürich, Switzerland.
authors.forename: S Y
authors.initials: SY
authors.lastname: Hess
authors.forename: M B
authors.initials: MB
authors.lastname: Zimmermann
mesh_terms: D002648:Child; D005260:Female; D006801:Humans; D007455:Iodine / Q000172:deficiency* / Q000378:metabolism* / Q000652:urine; D008297:Male; D011315:Preventive Medicine / Q000379:methods*; D012016:Reference Values; D012574:Schools; D012727:Sex Characteristics; D013557:Switzerland; D013961:Thyroid Gland / Q000000981:diagnostic imaging*; D014463:Ultrasonography; D014944:World Health Organization
chemical_list: D007455:Iodine