title: Low Goiter Rate Associated with Small Average Thyroid Volume in Schoolchildren after the Elimination of Iodine Deficiency Disorders.
abstract: BACKGROUND
  After the implementation of the universal salt iodization (USI) program in 1996, seven cross-sectional school-based surveys have been conducted to monitor iodine deficiency disorders (IDD) among children in eastern China.
  
  
  OBJECTIVE
  This study aimed to examine the correlation of total goiter rate (TGR) with average thyroid volume (Tvol) and urinary iodine concentration (UIC) in Jiangsu province after IDD elimination.
  
  
  METHODS
  Probability-proportional-to-size sampling was applied to select 1,200 children aged 8-10 years old in 30 clusters for each survey in 1995, 1997, 1999, 2001, 2002, 2005, 2009 and 2011. We measured Tvol using ultrasonography in 8,314 children and measured UIC (4,767 subjects) and salt iodine (10,184 samples) using methods recommended by the World Health Organization. Tvol was used to calculate TGR based on the reference criteria specified for sex and body surface area (BSA).
  
  
  RESULTS
  TGR decreased from 55.2% in 1997 to 1.0% in 2009, and geometric means of Tvol decreased from 3.63 mL to 1.33 mL, along with the UIC increasing from 83 μg/L in 1995 to 407 μg/L in 1999, then decreasing to 243 μg/L in 2005, and then increasing to 345 μg/L in 2011. In the low goiter population (TGR < 3.9%), TGR was positively associated with average Tvol (r = 0.99); UIC showed a non-linear association with average Tvol, and UIC > 300 μg/L was associated with a smaller average Tvol in children.
  
  
  CONCLUSIONS
  After IDD elimination in Jiangsu province in 2001, lower TGR was associated with smaller average Tvol. Average Tvol was more sensitive than TGR in detecting the fluctuation of UIC. A UIC of 300 μg/L may be defined as a critical value for population level iodine status monitoring.
authors.affiliation: Department of Epidemiology and Statistics, School of Public Health, Nanjing Medical University, Nanjing, China; Department of Environmental and Endemic Disease Control and Prevention, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, China.
authors.forename: Peihua
authors.initials: P
authors.lastname: Wang
authors.affiliation: Department of Environmental and Endemic Disease Control and Prevention, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Sun
authors.affiliation: Department of Environmental and Endemic Disease Control and Prevention, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, China.
authors.forename: Li
authors.initials: L
authors.lastname: Shang
authors.affiliation: Department of Environmental and Endemic Disease Control and Prevention, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, China.
authors.forename: Qinglan
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Department of Environmental and Endemic Disease Control and Prevention, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, China.
authors.forename: Yingxia
authors.initials: Y
authors.lastname: He
authors.affiliation: Department of Environmental and Endemic Disease Control and Prevention, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, China.
authors.forename: Zhigao
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Department of Environmental and Endemic Disease Control and Prevention, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, China.
authors.forename: Yonglin
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Department of Environmental and Endemic Disease Control and Prevention, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, China.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Environmental and Endemic Disease Control and Prevention, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, China.
authors.forename: Qingqing
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Department of Environmental and Endemic Disease Control and Prevention, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, China.
authors.forename: Jinkou
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Department of Epidemiology and Statistics, School of Public Health, Nanjing Medical University, Nanjing, China.
authors.forename: Hongbing
authors.initials: H
authors.lastname: Shen
mesh_terms: D002648:Child; D002681:China; D005260:Female; D006042:Goiter / Q000453:epidemiology* / Q000517:prevention & control; D006801:Humans; D007455:Iodine / Q000008:administration & dosage / Q000652:urine*; D008297:Male; D013961:Thyroid Gland / Q000473:pathology*
chemical_list: D007455:Iodine