The bone density of os calcis were measured with ultrasonic bone densitometry in 6, 680 healthy rural women in Mie Prefecture. Serum BGP and B-ALP levels were measured in 350 and 450 randomly selected cases respectively. The relations between their titers and bone loss with advancing age were also assessed. The BGP and B-ALP values began to rise in those subjects aged around 45 years. The elevated levels seemed to be kept till they became 70 years old. In this period, they might have massive bone loss with a high bone turnover, if they did not have an adequate calcium intake and exercise.
During this longitudinal observation, we measured bone density in 795 women 1, 062 times over a period of five years, with the initial bone mass value set at 100% and all the subsequent values expressed as a percentage of the initial value. Its value increased for about 106% and decreased from 95 to 91% in five years. By age, its numbers increased for 30% to 40% for those in their 40s and 60s, respectively. Overall, the decreases were significant (p<0.05) but the increases were not significant. In the low bone density group with the initial values below 59, only 21 cases of the total 91 had increased values thereafter, but 78% of them had kept the initial values, so they were advised to use caution against bone fracture in daily life and suitable treatments were recommended.
Many factors are associated with osteporosis. Presumably, lifestyle improvements alone would not serve to prevent its outbreak, but the authors believe that the findings of this study may cast light on the issue of osteoporosis for Japan, whose population is rapidly aging.