title: Comparison of 2 methods for estimating the prevalences of inadequate and excessive iodine intakes.
abstract: BACKGROUND
  Prevalences of iodine inadequacy and excess are usually evaluated by comparing the population distribution of urinary iodine concentration (UIC) in spot samples with established UIC cutoffs. To our knowledge, until now, dietary intake data have not been assessed for this purpose.
  
  
  OBJECTIVE
  Our objective was to compare 2 methods for evaluating the prevalence of iodine inadequacy and excess in sex- and life stage-specific subgroups of the US population: one that uses UIC cutoffs, and one that uses iodine intake cutoffs.
  
  
  METHODS
  By using the iodine concentrations of foods measured in the US Food and Drug Administration's Total Diet Study (TDS), dietary intake data from the NHANES 2003-2010, and a file that maps each NHANES food to a TDS food with similar ingredients, we estimated each NHANES participant's iodine intake from each NHANES food as the mean iodine concentration of the corresponding TDS food in samples gathered over the same 2-y period. We calculated prevalences of iodine inadequacy and excess in each sex- and life stage-specific subgroup by both the UIC cutoff method and the iodine intake cutoff method-using the UIC values and dietary intakes reported for NHANES participants who provided both types of data-and compared the prevalences across methods.
  
  
  RESULTS
  We found lower prevalences of iodine inadequacy across all sex- and life stage-specific subgroups with the iodine intake cutoff method than with the UIC cutoff method; for pregnant females, the respective prevalences were 5.0% and 37.9%. For children aged ≤8 y, the prevalence of excessive iodine intake was high by either method.
  
  
  CONCLUSIONS
  The consideration of dietary iodine intake from all sources may provide a more complete understanding of population prevalences of iodine inadequacy and excess and thus better inform dietary guidance than consideration of UIC alone. Methods of adjusting UIC for within-person variation are needed to improve the accuracy of prevalence assessments based on UIC.
authors.affiliation: Center for Food Safety and Applied Nutrition, US Food and Drug Administration, College Park, MD; wenyen.juan@fda.hhs.gov.
authors.forename: WenYen
authors.identifier: http://orcid.org/0000-0002-1658-2848
authors.initials: W
authors.lastname: Juan
authors.affiliation: Center for Food Safety and Applied Nutrition, US Food and Drug Administration, College Park, MD;
authors.forename: Paula R
authors.initials: PR
authors.lastname: Trumbo
authors.affiliation: Center for Food Safety and Applied Nutrition, US Food and Drug Administration, College Park, MD;
authors.forename: Judith H
authors.initials: JH
authors.lastname: Spungen
authors.affiliation: Office of Dietary Supplements, NIH, Bethesda, MD;
authors.forename: Johanna T
authors.initials: JT
authors.lastname: Dwyer
authors.affiliation: Department of Statistics, Iowa State University, Ames, IA;
authors.forename: Alicia L
authors.initials: AL
authors.lastname: Carriquiry
authors.affiliation: Westat, Rockville, MD; and.
authors.forename: Thea P
authors.initials: TP
authors.lastname: Zimmerman
authors.affiliation: Office of Dietary Supplements, NIH, Bethesda, MD;
authors.forename: Christine A
authors.initials: CA
authors.lastname: Swanson
authors.affiliation: University of Hawaii Cancer Center, Honolulu, HI.
authors.forename: Suzanne P
authors.initials: SP
authors.lastname: Murphy
mesh_terms: D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000652:urine; D002648:Child; D002675:Child, Preschool; D004032:Diet; D004034:Diet Surveys / Q000379:methods*; D005260:Female; D006801:Humans; D007223:Infant; D007455:Iodine / Q000008:administration & dosage* / Q000172:deficiency / Q000652:urine; D008297:Male; D008875:Middle Aged; D015596:Nutrition Assessment; D009749:Nutrition Surveys; D044343:Overnutrition; D011247:Pregnancy; D015995:Prevalence; D012016:Reference Values; D016482:Urinalysis / Q000379:methods; D055815:Young Adult
chemical_list: D015415:Biomarkers; D007455:Iodine
keywords: Total Diet Study; dietary surveys; food content; iodine; urinary iodine; variability