Objective:To explore the effect of physical development on thyroid volume of children aged 8 - 10 years in Sichuan Province, and explore the thyroid volume correction method suitable for school-age children, so as to accurately prevent and control iodine deficiency disorders.Methods:From June to July 2020, Shuangliu District of Chengdu City, Pengshan District of Meishan City, Miyi County of Panzhihua City and Qingchuan County of Guangyuan City were selected as the survey counties (districts). One township (town and street) was selected from each county (district) according to the five directions of East, West, South, North and Middle, one primary school was selected from each township (town and street), and 40 children aged 8 - 10 years (gender and age balanced) were selected as the survey subjects from each primary school, height and weight were measured, the body mass index (BMI) and body surface area (BSA) were calculated. Thyroid volume was measured by B-ultrasound, and the different thyroid volume indexes [height volume index 1 (HVI1), height volume index 2 (HVI2), body mass volume index (BMIV), weight and height volume index (WHVI), body surface volume index (BSAV)] were calculated, respectively. Urine samples of all children were collected, the iodine concentration in urine was measured, and the correlation between different measurement indexes and children's growth and development indexes was analyzed.Results:A total of 805 children aged 8 - 10 years were investigated, including 403 boys and 402 girls. There were 312, 288 and 205 children in the 8-, 9- and 10-year-old groups, respectively. A total of 805 urine samples were collected, and the median urinary iodine was 251.4 μg/L. There was no statistically significant difference in thyroid volume between boys and girls ( Z = - 0.44, P = 0.661), but was statistically significant difference between ages ( H = 64.95, P < 0.001). In all age groups, thyroid volume was positively correlated with height and weight (8-year-old group: r = 0.29, 0.42, P < 0.001; 9-year-old group: r = 0.29, 0.41, P < 0.001; 10-year-old group: r = 0.34, 0.47, P < 0.001). In all age groups, after HVI1 correction, thyroid volume was positively correlated with height and weight (8-year-old group: r = 0.13, 0.32, P < 0.05; 9-year-old group: r = 0.12, 0.30, P < 0.05; 10-year-old group: r = 0.18, 0.37, P < 0.05). In all age groups, there was a positive correlation between thyroid volume and weight after HVI2 correction (8-year-old group: r = 0.20, P < 0.001; 9-year-old group: r = 0.17, P = 0.004; 10-year-old group: r = 0.26, P < 0.001). In the 8- and 10-year-old groups, there was a positive correlation between thyroid volume and height after BMIV correction ( r = 0.20, P < 0.001; r = 0.21, P = 0.003). In all age groups, there was a negative correlation between thyroid volume and height and weight after WHVI correction (8-year-old group: r = - 0.35, - 0.37, P < 0.001; 9-year-old group: r = - 0.38, - 0.39, P < 0.001; 10-year-old group: r = - 0.31, - 0.38, P < 0.001). In the 8-year-old group, there was a positive correlation between thyroid volume and weight after BSAV correction ( r = 0.11, P = 0.045). Conclusions:Thyroid volume is closely related to height and weight. It may be inappropriate to judge goiter in children only based on age. After the preliminary comparison of five correction methods, it is found that BSAV is better.

Pure drug-assembled nanomedicines (PDANs) are currently under intensive investigation as promising nanoplatforms for cancer therapy. However, poor colloidal stability and less tumor-homing ability remain critical unresolved problems that impede their clinical translation. Herein, we report a core-matched nanoassembly of pyropheophorbide a (PPa) for photodynamic therapy (PDT). Pure PPa molecules are found to self-assemble into nanoparticles (NPs), and an amphiphilic PEG polymer (PPa-PEG