1, sex hormones: especially estrogen secretion is reduced, its mechanism of action is to directly inhibit bone resorption; protect bone tissue from excessive resorption by antagonizing PTH and reducing the sensitivity of bone tissue to PTH; participate in the synthesis of proteins necessary for osteogenesis; insufficient sex hormones lead to insufficient bone matrix formation. 2.Insufficient secretion of calcitonin: calcitonin directly inhibits the process of bone resorption and reduces the change of bone primitive cells into osteoblasts. 3, secondary parathyroid hyperplasia and PTH hypersecretion: PTH acts directly on osteoclasts and osteoblasts, which is an increase in lysosomal hydrolase synthesis and enhanced bone resorption. 4, Negative balance of calcium metabolism: causes secondary PTH hypersecretion. 5.Protein, vitamin C and other nutrient deficiencies. 6, other factors: race, region, dietary habits, genetics and other related.