Age-related changes in bone density among healthy Greek males

Abstract

Osteoporosis in men is increasingly recognized as a problem in clinical medicine, but it has received much less attention than its counterpart in women. It is termed idiopathic if no known cause of bone disease can be identified clinically or in the laboratory. The true incidence of idiopathic osteoporosis (IO) in males is difficult to estimate because population characteristics and referral patterns differ so widely. The aim of this study was to investigate the incidence of IO in healthy Greek male volunteers by measuring bone mineral density (BMD) at four skeletal sites and examining the relations among age, BMI, and bone status. This type of information has not yet been published. We considered osteoporosis to be present when the BMD was less than or equal to -2.5 SD from the average value for healthy young men. Three hundred and sixty-three normal male volunteers were investigated. The mean age was 51.3+/-8.7 yr, and BMI was 27.5+/-3.7 kg/m2. In all subjects BMD at four skeletal sites - lumbar spine (LS), femoral neck (FN), Ward's triangle (WT), and finally trochanter (T) - was measured using dual-energy X-ray absorptiometry (DEXA). T-score, Z-score and g/cm2 values were estimated. Forty-four subjects (11%) had BMD< or =-2.5 SD (T-score). The mean age and BMI for the men with decreased BMD was 54.8+/-6.4 yr and 26.3+/-3.3 kg/m2, whereas mean age and BMI for those with normal BMD was 51.0+/-8.9 yr and 27.6+/-3.6 kg/m2, respectively. These differences were statistically significant (p<0.001 and p<0.05, respectively). A positive correlation was found between BMI and bone density (g/cm2) at three skeletal sites: LS (r=0.235, p<0.001), WT (r=0.126, p<0.001) and FN (r=0.260, p<0.001). A positive correlation was also found between BMI and T-score at all skeletal sites studied: LS (r=0.276, p<0.001), WT (r=0.133, p<0.05), FN (r=0.233, p<0.001), and T (r=0.305, p<0.001). Finally, a positive correlation was also found between BMI and Z-score: LS (r=0.256, p<0.001), WT (r=0.117, p<0.005), FN (r=0.240, p<0.001), and T (r=0.187, p<0.001). A negative correlation was found between age and bone density (g/cm2) at FN (r=-0.157, p<0.01) and WT (r=-0.183, p<0.001). The same was true between age and T-score at FN only (r=0.137, p<0.05). Furthermore, a similar correlation was found between age and Z-score at LS (r=0.174, p<0.001). When ANOVA one-way analysis was used, a significant difference was found between the different age groups and BMD (g/cm2) at FN, T, and WT (p<0.001 for all sites). For T-score, a significant difference between age groups was found only at FN (p<0.005). Finally, a significant difference in Z-score was found at FN (p<0.001) and LS (p<0.005). When multiple regression analysis was applied, it was found that BMD (g/cm2) at two sites, FN and WT, independently correlated with age and BMI (FN: p<0.001 for both, WT: p<0.01 and p<0.05, respectively). Finally, we found an accelerated trend toward decreased BMD (g/cm2), when the odds ratio was applied. In conclusion, this study demonstrated that 11% of otherwise healthy Greek men had BMD less than or equal to -2.5 SD. A strong association was found between BMD (g/cm2) and age at three skeletal sites when ANOVA one-way analysis was applied. Moreover, BMD was positively correlated with BMI and negatively correlated with age. Currently available data are sparse and much more research is needed to increase our understanding concerning the etiology of this condition as well as illuminating the relationship between bone density and fracture.