Bone turnover and vascular ossification in chronic kidney disease (CKD). Basically, bone cells have less vitality in patients with CKD than in normal persons. Thus, low bone turnover is part of the innate character of CKD. High PTH serum levels will overcome the indolent bone cells and lead to high turnover bone disease with the characteristics of relatively higher bone resorption than bone resorption. The high turnover status in SHPT can induce increased bone demineralization, which will increase calcium and inorganic phosphate release from bone into circulation. In contrast, overtreatment of CKD patients with Ca-salts, VDRA, or aluminum may cause them to develop low turnover bone disorders and low serum PTH levels. In patients with low bone turnover status, the decreased bone mineralization makes it difficult for calcium and inorganic phosphate to enter into bone, resulting in increased serum calcium and inorganic phosphate. Both high and low bone turnover disorders are characterized by a relatively higher degree of bone resorption than bone formation, which may contribute to the elevated serum calcium and inorganic phosphate levels, and aggravate vascular calcification/ossification.
