Burckhardt P
Department of Internal Medicine, University Hospital-CHUV, Lausanne, Switzerland.
Exp Gerontol. 1990;25(3-4):325-9. doi: 10.1016/0531-5565(90)90069-e.
The aging of bone is conditioned by intrinsic and extrinsic factors. The decrease of bone density, of cortical and of trabecular bone volume with age goes along with an increase of interstitial trabecular bone (Courpron, 1981), in addition to other intrinsic structural changes. Interstitial bone has a lower cellularity and a lower metabolic activity than the bone tissue which is closer to the trabecular surface. This increase of interstitial bone serves as an example for the supposed decrease of bone cellularity, cellular activity, and hormonal receptors with age in bone. Therefore, the "playground" for calciotropic hormones is reduced in advanced age, independently from the hormonal changes which will be discussed thereafter. The relative role of this decrease of the target organ with age is not yet fully understood. The process of aging can interfere with each step of calcium metabolism from calcium intake and absorption, vitamin D intake and absorption to vitamin D production, hydrolysation and action, as well as to secretion and action of calciotropic hormones such as PTH, calcitonine, and gonadal steroids.
骨骼老化受内在和外在因素的制约。随着年龄增长，骨密度、皮质骨和小梁骨体积下降，同时伴有小梁间隙骨增加（库尔普龙，1981年），此外还有其他内在结构变化。间隙骨的细胞密度和代谢活性低于靠近小梁表面的骨组织。间隙骨的这种增加体现了随着年龄增长骨骼中骨细胞密度、细胞活性和激素受体的假定下降。因此，促钙激素的“作用场所”在老年时会减少，这与后文将要讨论的激素变化无关。靶器官随年龄增长而功能减退的相对作用尚未完全明了。衰老过程会干扰钙代谢的各个环节，从钙的摄入与吸收、维生素D的摄入与吸收到维生素D的生成、水解及作用，以及促钙激素如甲状旁腺激素、降钙素和性腺类固醇的分泌与作用。
