[Secondary osteoporosis or secondary contributors to bone loss in fracture. Vitamin D deficiency and fracture].

Vitamin D plays an important role in maintaining bone and calcium metabolism. Vitamin D deficiency causes not only low bone mineral density via secondary hyperparathyroidism, but also impairment of bone mineralization. Vitamin D deficiency also increases the risk of fall. Thus, vitamin D deficiency results in increased fracture risk. Serum 25 (OH) D level reflects Vitamin D store and more than 30 ng/mL is recommended for bone health, but the measurement of serum 25 (OH) D is not reimbursed by Japanese health insurance system. Vitamin D supplementation to vitamin D deficient osteoporotics reduces the fracture incidence by both increasing bone mineral density and reducing falls. Evaluation of vitamin D status and its adequate supplementation are prerequisite for proper osteoporosis management.