The human endoskeleton is composed of a collagen-containing organic matrix upon which is deposited a crystalline mineral phase. The strength and structural properties of bone depend on its resiliency, tensile properties, and compressive strength. Bone weakness thus develops whenever there are changes in the formation of the organic matrix, in the deposition or resorption of the mineral phase, or in the cells that form and remodel bone. 1 Bone is a dynamic living tissue that is constantly being formed and remodeled. The mineral phase deposited within the organic matrix contains 99% of body calcium, 80% to 85% of body phosphate, and most of the magnesium. Bone serves as the main depot of these minerals. It is utilized to maintain stable values of these ions in the extracellular fluid and is particularly necessary to stabilize the electrical potential of neural membranes. 2 In order to estimate the total body calcium