Factors affecting thyroid volume in adolescent students attending a rural middle school in East Hangzhou, China

To investigate the thyroid volume (Tvol) and to explore factors that affects it among 12 to 15-year-olds attending a rural middle school in east Hangzhou, China.

A cross-sectional survey of middle school students attending a rural middle school in east Hangzhou, China was conducted. Height, weight and other physical development related indicators in middle school students were measured. The thyroid size was measured using ultrasound, and the thyroid volume calculated.

The median (P₂₅, P₇₅) of the thyroid volume in 596 middle school students from a rural middle school in east Hangzhou, China was 6.69 (5.66, 7.98) mL. Our study enrolled 305 male students (51.2%) and 291 female students (48.8%). The height, weight and thyroid volume of middle school students increased with age. Univariate analysis revealed that height, weight, body mass index (BMI) and body surface area (BSA) were positive correlated with thyroid volume (p<0.01).The correlation between BSA and thyroid volume was significant (Spearman's rho=0.473, p<0.01). Multiple linear regression analysis revealed that BSA was positive and significantly correlated with the thyroid volume (p<0.05). Regression equation was Y=-2.532 + 6.186×BSA.

The thyroid volume is not only affected by age, but it is also affected by growth and development. Goiter cannot only be assessed based on age, gender and thyroid volume. However, this study established that BSA not only presented the strongest correlation with thyroid volume (Spearman's rho=0.473), but also had a strong correlation with physical development, taking into account the growth and development of middle school students, and showed greater stability. Therefore, we recommend inclusion of BSA as a reference standard in the measurement of the thyroid volume.