A normal reference of bone mineral density (BMD) measured by dual energy X-ray absorptiometry in healthy thai children and adolescents aged 5-18 years: a new reference for Southeast Asian Populations

Abstract

Ethnic-specific normative data of bone mineral density (BMD) is essential for the accurate interpretation of BMD measurement. There have been previous reports of normative BMD data for Caucasian and Asian children including Japanese, Chinese, Korean and Indian. However, the normative BMD data for Southeast Asian including Thai children and adolescents are not currently available. The goals of our study were 1) to establish normative data of BMD, bone mineral content (BMC), bone area (BA) and lean body mass (LBM) for healthy Thai children and adolescents; aged 5-18 years measured by dual energy X-ray absorptiometry (DXA, Lunar Prodigy) and 2) to evaluate the relationships between BMD vs. age, sex, puberty, weight, height, calcium intake and the age of menarche in our population. Gender and age-specific BMD (L2-4; LS and total body; TB), BMADLS (apparent BMD of the lumbar spine), BMC (L2-4 and total body), BA (L2-4 and total body) and LBM were evaluated in 367 children (174 boys and 193 girls). All parameters increased progressively with age. A rapid increase in BMD, BMC and BMADLS was observed at earlier ages in girls. Gender and Tanner stage-specific BMD normative data were also generated. The dynamic changes of BMD values from childhood to early and late puberty of Thai children appeared to be consistent with those of Caucasian and Asian populations. Using a multiple-regression, weight and Tanner stage significantly affected BMDLS, BMDTB and BMADLS in both genders. Only in girls, height was found to have significant influence on BMDTB and BMADLS. The positive correlation between BMD and several demographic parameters, except the calcium intake, was observed. In summary, we established a normal BMD reference for Thai children and adolescents and this will be of useful for clinicians and researchers to appropriately assess BMD in Thais and other Southeast Asian children.

Figure 1. Relationships between age vs. BMD of the lumbar spine (BMDLS; grams per cm²), BMAD of the lumbar spine (BMADLS; grams per cm³) and BMD of the total body (BMDTB; gram per cm²) among boys and girls.

The lines show the best- fitted function with the factors age, age² and age³ (cubic function) for girls and age and age² (quadratic function) for boys.

Figure 2. Relationships between age vs. BMC of the lumbar spine (BMCLS; grams), BMC of the total body (BMCTB; grams), BA of the lumbar spine (BALS; cm²), BA of the total body (BATB; cm²) and lean body mass (LBM; grams) among boys and girls.

The lines show the best- fitted function with the factors age, age² and age³ (cubic function) for girls and age and age² (quadratic function) for boys.

Figure 3. BMD of the lumbar spine (BMDLS; grams per cm²) and total body (BMDTB; gram per cm²) at different Tanner stages among boys and girls.

^*P<0.05, **P<0.01, ***P<0.001 compared with previous Tanner stage.

Figure 4. Comparison between our current Thai vs. Indian and Chinese BMD normative data in children and adolescents among boys and girls.

These figures were drawn based on data of the mean ± 2SD available from references , . The lines show mean ± 2SD. Thai BMDLS values are higher than those of Indian children and adolescent for both genders. Comparing to Chinese children, Thai children have higher BMDTB values for both genders.