Sonographic measurement of the volume of the thyroid gland in healthy children.

This study was designed to establish the normal size of the thyroid gland in children. Real-time ultrasound images of the thyroid gland in 126 healthy children were analyzed to determine the thyroid gland volume. Assuming each lobe to be a prolated spheroid, the long axis diameter (D1), short axis diameter (D2) and thickness (D3) were measured. The volume of each lobe (V) was estimated, using a standard geometric formula: V = D1 x D2 x D3 x lambda/6. The total volume of the thyroid gland was calculated as the sum of each lobe. The thyroid gland volumes were correlated with age, height, weight and body surface area. Correlation with height (r = 0.82, p less than 0.01) was as good as or better than with the other variables. Mean thyroid gland volumes as a function of height were obtained. No significant difference was observed between males and females in each height group (p less than 0.05).