Establishment of Thyroid Volume Reference Curves for Children in Xinjiang: An Exploration of Goiter Diagnosis and the Role of Iodine Nutrition

The validity of applying universal diagnostic standards across diverse populations is a critical public health concern. This study challenges the suitability of China's national thyroid volume (TTV) criteria by establishing region-specific reference curves for 404 children aged 7-13 years in Xinjiang. Our new sex-specific curves, constructed using GAMLSS models, revealed a goiter prevalence of only 1.5%, a stark contrast to the 9.5% in males and 11.7% in females diagnosed using the national standard (McNemar's test, P < 0.001). This discrepancy underscores a significant overestimation by the current national criteria. Furthermore, our analysis elucidated a nuanced role for iodine: while individual iodine indicators (urinary, salivary, and serum) exhibited significant nonlinear associations with TTV, a composite iodine index showed a protective linear negative correlation (P = 0.012). These findings demonstrate that region-specific standards are imperative for accurate goiter diagnosis. They also suggest that in iodine-sufficient populations, the relationship between iodine and thyroid health is a complex physiological modulation rather than a simple risk paradigm.