Staud Roland
University of Florida, PO Box 100221, Gainesville, FL 32610-0221, USA.
Curr Rheumatol Rep. 2005 Oct;7(5):356-64. doi: 10.1007/s11926-005-0020-0.
Vitamin D is a fat-soluble steroid that is essential for maintaining normal calcium metabolism. In vitamin D deficiency, calcium absorption is insufficient and cannot satisfy the body's needs. Consequently, parathyroid hormone production increases and calcium is mobilized from bones and reabsorbed in the kidneys to maintain normal serum calcium levels--a condition defined as secondary hyperparathyroidism. Most organs, including the gut, brain, heart, pancreas, skin, kidneys, and immune system have receptors for 1,25 (OH)vitamin D. Furthermore, all of these organs have the capacity to synthesize 1,25 (OH)vitamin D from vitamin D. Extensive research suggests that vitamin D deficiency is common and represents a global health problem. Clinical consequences related to low vitamin D levels include not only osteomalacia, osteoporosis, and rickets, but also neuro-muscular dysfunction and fractures. Falls related to neuromuscular dysfunction lead to 40% of all nursing home admissions and are the largest single cause of injury-related deaths in elderly people. About one-third of all persons 65 and older fall at least once a year, resulting in more than 1.5 million emergency room treatments and more than 300,000 hospitalizations. Falls cause more than 11,000 deaths per year, most of them in elderly patients (> or = 75 years) who suffer hip fractures. It is well established that vitamin D deficiency not only has serious consequences for bone health, but also for other organ systems. Previous studies have shown that vitamin D supplementation reduces the number of fractures and directly improves neuromuscular function, thus helping to prevent falls and subsequent fractures. In addition, vitamin D appears to have other important functions as a regulator of cell differentiation and cell growth.
维生素D是一种脂溶性类固醇，对维持正常的钙代谢至关重要。在维生素D缺乏的情况下，钙吸收不足，无法满足身体需求。因此，甲状旁腺激素分泌增加，钙从骨骼中被动员出来并在肾脏中重吸收，以维持正常的血清钙水平——这种情况被定义为继发性甲状旁腺功能亢进。包括肠道、大脑、心脏、胰腺、皮肤、肾脏和免疫系统在内的大多数器官都有1,25（OH）维生素D的受体。此外，所有这些器官都有能力将维生素D合成1,25（OH）维生素D。广泛的研究表明，维生素D缺乏很常见，是一个全球性的健康问题。与低维生素D水平相关的临床后果不仅包括骨软化症、骨质疏松症和佝偻病，还包括神经肌肉功能障碍和骨折。与神经肌肉功能障碍相关的跌倒导致了所有养老院入院病例的40%，是老年人与损伤相关死亡的最大单一原因。所有65岁及以上的人中约有三分之一每年至少跌倒一次，导致超过150万次急诊治疗和超过30万次住院治疗。跌倒每年导致超过11000人死亡，其中大多数是患有髋部骨折的老年患者（≥75岁）。众所周知，维生素D缺乏不仅对骨骼健康有严重影响，对其他器官系统也有影响。先前的研究表明，补充维生素D可减少骨折数量，并直接改善神经肌肉功能，从而有助于预防跌倒和随后的骨折。此外，维生素D似乎还具有作为细胞分化和细胞生长调节剂的其他重要功能。
