Bone mineral density in children with Down's syndrome detected by dual photon absorptiometry.

Bone mineral density (BMD) in ten children with Down's syndrome (seven boys, three girls; aged 10-16 years) was measured by dual photon absorptiometry (DPA) using an M&SE OsteoTech 300 scanner. The BMD of the 2nd to 4th lumbar vertebrae was measured and the mean density presented as g cm-2. The BMD of Down's syndrome was compared with the BMD of normal Chinese children of the same age group. The results showed that the BMD in Down's syndrome was significantly lower compared to that found in normal children (P < 0.01). The percentage of decreased BMD is 8.47 +/- 2.69% (mean +/- 1 S.E.M.) in Down's syndrome compared to normal children of the same age group. The distribution curve of BMD against ages in Down's syndrome has a delay of 2.3 +/- 0.5 (mean +/- 1 S.E.M.) years compared to normal children. In our conclusion, the children with Down's syndrome have lower BMD than the normal children of the same age group. The causes of this abnormality may require further study in the future.