Study on influential factors and reference values for thyroid volume in Chinese children aged 6–12 years

Abstract

The purpose of this study was to research the factors influencing thyroid volume (TVOL) in 6∼12-year-old children and update the reference values. A cross-sectional study was carried out in iodine-sufficient areas of four provinces in China. Urine, edible salt, and drinking water samples were collected from children. Children’s height, weight, and TVOL were measured. Ridge regression was used to screen variables for solving the multicollinearity problem. Quantile regression was used to analyze the relationship between the quantiles of TVOL and other variables. In total, 5653 children aged 6∼12 years were enrolled in this study, including 2838 boys and 2815 girls. There was no significant difference in TVOL between boys and girls (P>0.05). Spearman correlation analysis showed that total TVOL was positively correlated with age, height, weight, BSA and BMI, and the correlation coefficients were 0.614, 0.625, 0.646, 0.653 and 0.488 respectively. Among them, the correlation between TVOL and BSA was the strongest. According to the ridge regression results, age and body surface area (BSA) influenced TVOL, and the ridge regression coefficients were 0.13 and 0.94 respectively. Quantile regression further showed that age and BSA had significant influences on the whole TVOL distribution (P<0.001). Therefore, the TVOL of children aged 6∼12 years in China was mainly influenced by age and BSA, and reference values for TVOL of different genders based on age and BSA were established.

Influencing Factors and New Reference Intervals of Adult Thyroid Volume in Iodine-Sufficient Areas of China

“…Thyroid volume is closely related to anthropometric indexes, and the effect of BSA on thyroid volume has been widely confirmed [10,18]. In our study, both male and female thyroid volumes were strongly correlated with BSA, and the quantile regression model coefficients for males and females reached 9.3 and 7.5, respectively, at the upper limit of the reference value.…”

“…A study in areas with high iodine levels in China found that although age, sex, and BSA can affect thyroid volume in children, when stratified by age, this age-related difference only occurred in the 8-to-9year-old group. However, among adults, sex has always affected thyroid volume [17,18]. This may be due to the anatomically larger thyroid and higher lean body mass in males [17] as well as different hormone secretion levels in adulthood.…”

“…For children, the results of Chen [22] found that age was only a strong predictor of median thyroid volume. An [18] found that only 44% of changes in TVOL were caused by changes in age and BSA. The findings of Guo among adults were consistent with ours, and the effect of age on thyroid volume was also not significant after adjusting for relevant factors [13].…”