DEVELOPMENT OF BONE MASS AND BONE-DENSITY OF THE SPINE AND FEMORAL-NECK - A PROSPECTIVE-STUDY OF 65 CHILDREN AND ADOLESCENTS

The bone mineral density (BMD, g/cm(2)) of the lumbar spine (L2-L4) an d femoral neck was measured twice with a I-year interval by dual energ y X-ray absorptiometry (DEXA) in 65 healthy children and adolescents a ged 7-20 years. In addition, the BMD values were corrected for the siz e of bones to obtain the bone volumetric density (BMD(vol), g/cm(3)) u sing a method developed previously. The annual increases of BMD and BM D(vol) in both spine and femoral neck were most marked in females at t he time of menarche (during the age of 11-13 years), and in males betw een the ages of 13 and 17 years. The males showed significantly higher values in their mean annual increment rates of femoral bone mineral c ontent (BMC) and femoral neck width, whereas no differences in spinal parameters were found. The acquisition of bone mass and bone density s topped or markedly diminished before the age of 20 years, supporting t he theory that the major portion of the peak bone mass is attained in late adolescence. We could not find any significant relationship betwe en the increment rate of bone density, and physical activity or calciu m intake. This study emphasizes the significant effect of puberty and genetic factors on the development of bone mass and density.