Purpose: To determine whether differences in vertebral bone densities or sizes account for gender differences in skeletal mass during growth.
Materials and methods: Quantitative computed tomography (CT) was used to measure the densities of cortical and cancellous bone and dimensions of the lumbar vertebral bodies in 196 healthy children and adolescents, ages 4-20 years.
Results: Neither cancellous nor cortical bone densities differed between boys and girls with age or level of sexual development. In contrast, the cross-sectional areas of the vertebral bodies were greater in boys than girls throughout childhood and adolescence. Even when prepubertal children were matched for chronologic age, bone age, height, and weight, the size of the vertebral bodies was 17% greater in boys. This disparity in vertebral body size increased with level of sexual development and was greatest at sexual maturity.
Conclusion: Lower vertebral bone mass of women as compared with men may result from early gender differences in the sizes of bones rather than differences in bone densities.