Lips Paul
Department of Endocrinology, Vrije Universiteit Medical Center, P.O. Box 7057, 1007 MB Amsterdam, The Netherlands.
J Steroid Biochem Mol Biol. 2004 May;89-90(1-5):611-4. doi: 10.1016/j.jsbmb.2004.03.040.
Moderate Vitamin D deficiency causes secondary hyperparathyroidism and bone loss, leading to osteoporosis and fractures. Controversy exists which circulating level of 25-hydroxyvitamin D (25OH)D is appropriate. The high incidence of hip fractures at northern latitudes suggest a relationship with Vitamin D deficiency. However, international studies show lower serum 25(OH)D levels in southern than in northern Europe. Serum 25(OH)D was not a risk factor for hip fractures in several epidemiological studies. The required serum 25(OH)D is usually established by assessing the point where serum parathyroid hormone (PTH) starts to rise. This point varied in several studies between 30 and 78 nmol/l. However, interlaboratory variation may also influence the apparent required serum 25(OH)D level. Dietary calcium intake influences serum PTH and serum PTH may influence the turnover of Vitamin D metabolites. A low calcium intake causes an increase of serum PTH and serum 1,25(OH)2D thereby decreasing the half life of serum 25(OH)D. While a low calcium intake may aggravate Vitamin D deficiency, a high calcium intake may have a Vitamin D sparing effect. With current knowledge, a global estimate for the appropriate serum 25(OH)D is 50 nmol/l.
中度维生素D缺乏会导致继发性甲状旁腺功能亢进和骨质流失，进而引发骨质疏松和骨折。关于循环中25-羟基维生素D（25OH）D的适宜水平存在争议。北半球纬度地区髋部骨折的高发病率表明其与维生素D缺乏有关。然而，国际研究显示，南欧人群血清25（OH）D水平低于北欧人群。在多项流行病学研究中，血清25（OH）D并非髋部骨折的危险因素。所需的血清25（OH）D水平通常通过评估血清甲状旁腺激素（PTH）开始升高的点来确定。在多项研究中，这一点在30至78 nmol/l之间有所不同。然而，实验室间的差异也可能影响表观所需的血清25（OH）D水平。膳食钙摄入量会影响血清PTH，而血清PTH可能会影响维生素D代谢产物的周转。低钙摄入量会导致血清PTH和血清1,25（OH）2D升高，从而缩短血清25（OH）D的半衰期。低钙摄入量可能会加重维生素D缺乏，而高钙摄入量可能会产生维生素D节约效应。根据目前的知识，全球适宜的血清25（OH）D估计值为50 nmol/l。
