title: Relationship between Iodine Content in Household Iodized Salt and Thyroid Volume Distribution in Children.
abstract: OBJECTIVE
  To assess the effect of different levels of salt iodine content on thyroid volume (ThV) distribution using data from the 1999, 2011, and 2014 Chinese national iodine deficiency disorder (IDD) surveys.
  
  
  METHODS
  Probability proportion to size (PPS) sampling method was used to obtain a representative national sample of 34,547, 38,932, and 47,188 Chinese children aged 8-10 years in 1999, 2011, and 2014 Chinese national IDD surveys, respectively. The iodine content in household iodized salt and urinary iodine concentration were measured and thyroid ultrasound examination was performed. The data were analyzed by SAS software using histograms and box plots. The skewness and kurtosis were calculated for testing the normality of ThV.
  
  
  RESULTS
  The median iodine content in household iodized salt dropped from 42.30 mg/kg in 1999 to 25.00 mg/kg in 2014. The median urinary iodine concentration of children aged 8-10 years decreased from 306.0 μg/L in 1999 to 197.9 μg/L in 2014. The median and interquartile range (IQR) of ThV in 1999, 2011, and 2014 surveys were 3.44 mL and 1.50 mL, 2.60 mL and 1.37 mL, 2.63 mL and 1.25 mL, respectively. The skewness and kurtosis of ThV distribution in 1999, 2011, and 2014 surveys were 1.34 and 5.84, 0.98 and 3.54, 1.27 and 5.49, respectively.
  
  
  CONCLUSIONS
  With reduced salt iodization levels, the median urinary iodine concentration and median ThV of children decreased significantly, and the symmetry of the ThV distribution improved.
authors.affiliation: Institute of Iodine Deficiency Disorders, Center for Endemic Disease Control, Chinese Center for Disease Control and Prevention, Harbin Medical University, Harbin 150081, Heilongjiang, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Chao
authors.affiliation: Jiangsu Center for Disease Control and Prevention, Nanjing 210009, Jiangsu, China.
authors.forename: Yu Fu
authors.initials: YF
authors.lastname: Zhang
authors.affiliation: Institute of Iodine Deficiency Disorders, Center for Endemic Disease Control, Chinese Center for Disease Control and Prevention, Harbin Medical University, Harbin 150081, Heilongjiang, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Liu
authors.affiliation: Qiqihar Medical University, Qiqihar 161000, Heilongjiang, China.
authors.forename: Yun Feng
authors.initials: YF
authors.lastname: Han
authors.affiliation: Institute of Iodine Deficiency Disorders, Center for Endemic Disease Control, Chinese Center for Disease Control and Prevention, Harbin Medical University, Harbin 150081, Heilongjiang, China.
authors.forename: Shou Jun
authors.initials: SJ
authors.lastname: Liu
mesh_terms: D002648:Child; D002681:China; D005260:Female; D006801:Humans; D007455:Iodine / Q000032:analysis / Q000172:deficiency*; D008297:Male; D009752:Nutritional Status; D017673:Sodium Chloride, Dietary / Q000032:analysis*; D013961:Thyroid Gland / Q000000981:diagnostic imaging*; D014463:Ultrasonography
chemical_list: D017673:Sodium Chloride, Dietary; C034024:iodized salt; D007455:Iodine
keywords: Children; Iodine deficiency disorders; Iodized salt; Thyroid volume; Universal salt iodization