Ultrasound Evaluation of Thyroid Gland Volume in Schoolchildren 7-11 years from West Kazakhstan

Objective: to determine thyroid volume by ultrasound in schoolchildren aged 7 to 11 years, from oil and gas areas of West Kazakhstan. Materials and Methods. During the period from May to December 2013 cross-sectional study was conducted on schoolchildren living in the oil and gas and clean areas of West Kazakhstan. A total of 815 schoolchildren aged 7-11 years who met the study criteria were included in the study. Anthropometry was measured before the ultrasound, then the expert radiologist conducted measurement of thyroid volume using a portable ultrasound machine according to recommendations of WHO. Urinary iodine was tested in 10% of students selected randomly. Results. The prevalence of goiter in our sample using the 97th percentile of the volume recommended by WHO / ICCIDD (2007) was 24.7 ± 1.50% (49.8% girls and 51.2% boys). Average thyroid volume measured by ultrasound in the oil and gas regions was 4.43 ± 1.66 ml, in a safe area of 2.9 ± 1.24 ml. The difference in thyroid volume was statistically significant p <0.0001. The difference in thyroid volume between boys compared areas was statistically significant ( p <0.0001): 4.62 ± 1.75 ml and 2.78 ± 0.93 ml; between girls 4.23 ± 1.53 ml and 3.05 ± 1.52 ml, respectively ( p <0.0001).Mean volume thyroid does not correlate with the age of the participants, but weakly correlated with BMI ( r = 0.3; p <0.0001). Median and 97th percentile thyroid volumes of our subjects were higher than the reference values reported to WHO. Median urinary iodine (UI) was 193 mg/l. Conclusion. Thyroid size of schoolchildren in west region of Kazakhstan is higher than the reference values reported to WHO. The high prevalence of goiter in the areas of oil and gas on of versus iodine-replete conditions available to the regional populations according to urinary iodine (UI) suggests the influence of other goitrogenic factors in the region and requires further study