Age-dependent skeletal physiology during post-natal growth

During post-natal growth, skeletal physiology undergoes changes which will ensure an optimal mineralisation of the growing skeleton, a process especially important to achieve a satisfactory peak bone mass. Changes will occur at skeletal, but also, extra-skeletal sites, and are most marked during infancy and adolescence. Based on the evolution of circulating and urinary markers of bone metabolism, bone formation rate appears to be coupled to growth rate, being highest during infancy and adolescence. Bone resorption is not as closely coupled, being highest at the beginning of life and decreasing thereafter. Extra-skeletal changes concern mainly the main regulators of bone formation (IGF) and mineralisation (1,25-dihydroxyvitamin D). A clear growth rat dependent regulation of vitamin D metabolism and a resulting clear growth rate dependent ability of the intestine to absorb calcium and phosphorus are found during childhood. (author)