Age-related endocrine deficiencies and fractures of the proximal femur. II Implications of vitamin D deficiency in the elderly

Abstract

Age is the most important empirical determinant of bone mass. Factors associated with ageing account for the slow phase of bone loss, which begins in cortical bone by the age of 40 and continues throughout life at a rate of about 0·6% per year. In trabecular bone, it may begin even earlier and continues at a rate of about 0·7% per year (Burger et al. 1994, Greenspan et al. 1994, May et al. 1994). Although this loss probably reflects the aggregate effects of several processes, bone mass and bone strength depend, in part, upon calcium balance. When the amount of calcium absorbed from the diet is insufficient, calcium must be withdrawn from bone, which contains 99% of the total body stores. In both sexes, active intestinal transport of calcium decreases with ageing, particularly after the age of 70. This decrease is partially accounted for by an age-related deficiency of