Bone Mineral Density Obtained by Peripheral Quantitative Computed Tomography (pQCT) in Middle-Aged and Elderly Japanese

Abstract

To clarify age-related changes in bone mineral density (BMD) by peripheral quantitative computed tomography (pQCT), 1,124 Japanese middle-aged and elderly community-dwelling people were examined. The BMD of the trabecular bone was assessed at the distal part of the radius (D50), and the BMD of the cortical bone was assessed at the diaphysis of the radius (P100). P100 during age 40 to 49 was significantly higher in females (1359.6±10.7 mg/cm3, mean±SE) than in males (1253.5±9.5 mg/cm3), while there was no difference in D50, 245.3±5.1 mg/cm3 in females and 293.0±5.5 mg/cm3 in males. Females and males aged 50 to 59 lost 8.09±2.08 (mean±SE) mg/cm3 and 3.80±1.77 mg/cm3 of D50 every year, respectively. As for P100, females lost 25.1 ±4.48 mg/cm3, and males lost 6.37±3.89 mg/cm3 every year. Because of these gender differences, both D50 and P100 were significantly higher in males than in females aged 50 and over. Assuming that the average BMD between ages 40 and 44 was the maximum bone mineral density (BMD max), the percentage change from the BMD max with age was examined. Females aged 60 to 69 whose BMD were under 70% of the BMD max made up 73.9% in D50 and 23.2% in P100. Only 21.1 % of males aged 60 to 69 showed less than 70% of the BMD max in D50 and only 3.8% in P100. The percentage decrease in BMD by age was larger in D50 than in P100 in both males and females. The individual difference in BMD was larger in D50 than in P100. These results suggest that pQCT may be useful to independently assess aging effects on cortical and trabecular bone density.