Changes in bone mineral, lean body mass and fat content as measured by dual energy X-ray absorptiometry: a longitudinal study.

Bone mineral density (BMD) and soft tissue composition were measured by dual energy X-ray absorptiometry (DXA) 3-4 years apart in 273 men and women aged 23-90. We found different rates of BMD loss in different skeletal regions. There were also different rates of BMD loss in different regions within the hip. Average rates of loss for male subjects 50 years of age and above for BMD total body were 0.1%/year and for femoral neck 1.5%/year, whereas lumbar spine (L2-L4) increased by 0.4%/year. Average rates of loss for female subjects 50 years of age and above for BMD total body were 0.0%/year, femoral neck 0.9%/year, and lumbar spine (L2-L4) 0.1%/year.