ULTRASONIC PARAMETERS OF BONE IN YOUNG NORMALS - EFFECT OF AGE AND SEX

This study was carried out in order to investigate the early effects o f ageing on both broadband ultrasound attenuation and speed of sound t hrough the os calcis. A total of 217 normal subjects, subdivided into 113 fertile women (age range 18-51 years, mean +/- 1 SD = 29.4 +/- 8.4 years) and 104 age-matched men (age range 20-49 years, mean +/- 29.3 +/- 7.1 years), were investigated. Mean broadband ultrasound attenuati on values in men (127.3 +/- 12.8 gB MHz(-1)) were significantly higher than those found in women (118.3 +/- 17.2, P < 0.001), whereas no sig nificant differences were found as far as mean speed of sound values w as concerned. Both broadband ultrasound attenuation (r = -0.196, P < 0 .046) and speed of sound (r = -0.226, P < 0.02) values were inversely related to age in men; only a decrease of speed of sound values with a ge was noted in women (r = -0.400, P < 0.001). Finally, there was a ve ry high significant correlation between broadband ultrasound attenuati on and speed of sound values in men (I = 0.458, P < 0.001), but this w as lacking in women. Admitting that the measurement of broadband ultra sound attenuation is influenced not only by bone density but also by t rabecular quantity, spacing and orientation, our results seem to indic ate that, even during adulthood, and well before the deleterious effec ts of oestrogen lack become apparent, structural properties of skeleta l tissue in female subjects are disadvantageous with respect to those found in male subjects. Furthermore, while there is a progressive and balanced involvement of both the elastic (as reflected by speed of sou nd) and the structural properties of skeletal tissue in men, an uncoup ling between the two is typical of women.