title: Estimation of the Prevalence of Inadequate and Excessive Iodine Intakes in School-Age Children from the Adjusted Distribution of Urinary Iodine Concentrations from Population Surveys.
abstract: The urinary iodine concentration (UIC), a biomarker of iodine intake, is used to assess population iodine status by deriving the median UIC, but this does not quantify the percentage of individuals with habitually deficient or excess iodine intakes. Individuals with a UIC <100 μg/L or ≥300 μg/L are often incorrectly classified as having deficient or excess intakes, but this likely overestimates the true prevalence.
  
  
  
  Our aim was to estimate the prevalence of inadequate and excess iodine intake in children (aged 4-14 y) with the distribution of spot UIC from iodine surveys.
  
  
  
  With the use of data from national iodine studies (Kuwait, Oman, Thailand, and Qatar) and a regional study (China) in children (n = 6117) in which a repeat UIC was obtained in a subsample (n = 1060), we calculated daily iodine intake from spot UICs from the relation between body weight and 24-h urine volume and within-person variation by using the repeat UIC. We also estimated pooled external within-person proportion of total variances by region. We used within-person variance proportions to obtain the prevalence of inadequate or excess usual iodine intake by using the Estimated Average Requirement (EAR)/Tolerable Upper Intake Level (UL) cutoff method.
  
  
  
  Median UICs in Kuwait, Oman, China, Thailand, and Qatar were 132, 192, 199, 262, and 333 μg/L, respectively. Internal within-person variance proportions ranged from 25.0% to 80.0%, and pooled regional external estimates ranged from 40.4% to 77.5%. The prevalence of inadequate and excess intakes as defined by the adjusted EAR/UL cutoff method was ∼45-99% lower than those defined by a spot UIC <100 μg/L or ≥300 μg/L (P < 0.01).
  
  
  
  Applying the EAR/UL cutoff method to iodine intakes from adjusted UIC distributions is a promising approach to estimate the number of individuals with deficient or excess iodine intakes.
authors.affiliation: Human Nutrition Laboratory, ETH, Zurich, Switzerland; Iodine Global Network, Ottawa, Canada; michael.zimmermann@hest.ethz.ch.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Zimmermann
authors.affiliation: Iodine Global Network, Ottawa, Canada;
authors.forename: Izzeldin
authors.initials: I
authors.lastname: Hussein
authors.affiliation: Ministry of Health, Muscat, Oman;
authors.forename: Samia
authors.initials: S
authors.lastname: Al Ghannami
authors.affiliation: Ministry of Health, Dubai, United Arab Emirates;
authors.forename: Salah
authors.initials: S
authors.lastname: El Badawi
authors.affiliation: Ministry of Health, Kuwait City, Kuwait;
authors.forename: Nawal M
authors.initials: NM
authors.lastname: Al Hamad
authors.affiliation: Ministry of Education, Kuwait City, Kuwait;
authors.forename: Basima
authors.initials: B
authors.lastname: Abbas Hajj
authors.affiliation: Supreme Council of Health, Doha, Qatar;
authors.forename: Mohamed
authors.initials: M
authors.lastname: Al-Thani
authors.affiliation: Supreme Council of Health, Doha, Qatar;
authors.forename: Al Anoud
authors.initials: AA
authors.lastname: Al-Thani
authors.affiliation: Institute of Nutrition, Mahidol University, Bangkok, Thailand;
authors.forename: Pattanee
authors.initials: P
authors.lastname: Winichagoon
authors.affiliation: Institute of Nutrition, Mahidol University, Bangkok, Thailand;
authors.forename: Tippawan
authors.initials: T
authors.lastname: Pongcharoen
authors.affiliation: Iodine Global Network, Ottawa, Canada; Rollins School of Public Health, Emory University, Atlanta, GA;
authors.forename: Frits
authors.initials: F
authors.lastname: van der Haar
authors.affiliation: Shanxi Institute for Prevention and Treatment of Endemic Disease, LinFen, China; and.
authors.forename: Jia
authors.initials: J
authors.lastname: Qing-Zhen
authors.affiliation: Human Nutrition Laboratory, ETH, Zurich, Switzerland;
authors.forename: Susanne
authors.initials: S
authors.lastname: Dold
authors.affiliation: Human Nutrition Laboratory, ETH, Zurich, Switzerland; Iodine Global Network, Ottawa, Canada;
authors.forename: Maria
authors.initials: M
authors.lastname: Andersson
authors.affiliation: Department of Statistics, Iowa State University, Ames, IA.
authors.forename: Alicia L
authors.initials: AL
authors.lastname: Carriquiry
mesh_terms: D000293:Adolescent; D015415:Biomarkers / Q000652:urine; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007455:Iodine / Q000008:administration & dosage / Q000172:deficiency / Q000652:urine*; D007730:Kuwait / Q000453:epidemiology; D008297:Male; D044342:Malnutrition / Q000453:epidemiology* / Q000652:urine; D009752:Nutritional Status; D009850:Oman / Q000453:epidemiology; D011780:Qatar / Q000453:epidemiology; D013785:Thailand / Q000453:epidemiology
chemical_list: D015415:Biomarkers; D007455:Iodine
keywords: EAR; Estimated Average Requirement; UL; iodine deficiency; iodine excess; iodine intake; tolerable upper limit; urinary iodine; within-subject variation