[Secular trend of bone mineral content decrease in human bone tissue: analysis of the data from Ural region].

Bone mineral content in rib samples from Ural region residents was analyzed depending on donors' gender, age and year of birth. Bone mineral content, that reflects the mineral density, was estimated as gram of minerals per 1 kg of wet bone mass. The period of sampling and measurements covered 1958-1988, the age of donors ranged from newborn to 99 years, birth years varied from 1872 to 1984, and the total number of samples was equal to 4685. A decrease in bone mineral density during 1958-1988 period was found in groups of close ages but different years of birth indicating an existence of the secular trend. For people born before 1920, the trend was insignificant. For people born in later years, a continuous decrease in bone mineral content was observed in groups of the same ages with an average rate of 3 g/kg per year, which is about 1% per year. Longitudinal and cross-sectional studies of bone mineral density provide different estimates of age dependent rate of bone mineral loss, and these values may differ by a factor of two. Different generations, i.e. people born in different periods of the XX century, have age-dependent features of bone mineral density specific for their groups.