[Bone density and mineral content in normal men. Measurement by dual photon densitometry]

The aim of this study was to measure whole body, L2 to L4 vertebral bodies and femoral neck bone density and mineral content, using a dual photon densitometer with a 153Gd source, in normal male subjects. One hundred twenty five males, aged 20 to 85 years, were studied. Subjects were separated, according to age in 5 year groups, with at least 10 subjects per group. Height did not show secular changes until 70 years of age, but a 9 kg increase in weight and a 3.8 kg/m2 increase in body mass index was observed. Lumbar spine bone density was 1.066 g/cm2 between 20 and 29 years and did not change with increasing age. In the same age group, femoral neck density was 1.034 g/cm2 and it decreased steadily after the age of 40 (slope = -0.003) with an annual loss of 0.23%. Total mineral content decreased from 2.477 g in the first age group to 2.316 g in subjects 70 years old or older. This represents a net loss of 6.5% in this period. Compared with normal females from a previous study, young men have similar spine and femoral neck densities than young women until the age of 50. In women over this age, there is a steady decline in lumbar spine density and the decrease in femoral neck density is more marked than in men. Also, total mineral content is higher in young men and its 6.5% loss with age is much lesser than the 31.6% loss observed in women.