Measuring of goiter by ultrasonography is one of the generally accepted methods for iodine nutrition assessment. Discordance between previously used and lately proposed thyroid volume (TV) reference values (TVRV) is the subject of discussion and makes it difficult to properly interpret the effects of iodine prophylaxis.
Aim: To establish TVRV for Polish schoolchildren population.
Material and methods: 2903 schoolchildren aged 612 years (1418 boys, 1485 girls) were studied in years 2006 and 2008 (all subject living in the Polish coastal area previously recognized as iodine sufficient). Seventy-two percent of subjects were born after implementation of the obligatory iodine prophylaxis model. TV was assessed in all children ultrasonographically according to standard procedures by two trained physicians. Urinary iodine concentration (UIC) was assessed in casual morning urine sample by Sandell-Kolthoffs method.
Results: Median UIC was 96.02 μg/l (mean 109.51±70.06 μg/l). UIC higher than 100 μg/l was noted in 47.5% of children. Goiter frequency (GF) was 2.2% when TVRV by Delange et al. were applied, and 54.2% when TVRV by Zimmermann et al. were used. GF didnt differ significantly between subgroups with UIC below and over 100 μg/l, regardless TVRV used. The 50th and 97th percentile of TV (ml) were: (a) for boys: 6 years 2.75 and 4.80, 7 years 3.58 and 5.41, 8 years 3.91 and 6.44, 9 years 4.44 and 7.13, 10 years 5.13 and 7.65, 11 years 5.44 and 8.56, 12 years 6.50 and 11.31, respectively; (b) for girls: 6 years 2,60 and 4.60, 7 years 3.42 and 5.21, 8 years 3.90 and 6.54, 9 years 4.29 and 6.90, 10 years 5.02 and 8.40, 11 years 5.58 and 10.06, 12 years 7.10 and 12.23, respectively.
Conclusions: i) Newly proposed TVRV dont seem to be applicable for populations with recently improved iodine nutrition, and should not be used for therapeutic purposes; ii) establishing of regional TVRV for ethnically uniform populations with adequate iodine intake is necessary.