Bone Density and Skeletal Maturation As Indexes of Mineral Status in Children

suggests that bone density is a physical attribute which like height, weight and basal metabolic rate has a characteristic value with fairly wide individual variations for different age groups. With due respect for various physiologic factors which change concomitantly with the density of bone and age, quantitative measurement of density of bone in growing children may serve as a useful criterion in the determination of their mineral status. Data presented by Williams et al.2 on bone density measurements on rats during the period of growth indicate that a diet adequate in calcium (0.5 per cent) and in all other nutrients results in an orderly increase in bone density with age until maturity. Unpublished data from this laboratory show that a diet differing only in calcium content (0. 1 per cent) resulted in retarded growth and lower bone density for corresponding age groups in first generation animals. Although young were born to parents raised on this diet, many of the offspring died before weaning. Animals which survived to maturity were markedly retarded in growth and produced no young. The animal which sur-vived for one year laid up calcium reserves, indicated by a high bone density value. This was interpreted as being the result of reduced requirement for calcium because of stunte