VDR and osteoporosis: The effectiveness of osteoporosis treatment is believed to be related to factors such as polymorphisms of the vitamin D receptor (VDR) [62], and biochemical markers of bone turnover (BTMs), such as the bone alkaline phosphatase (bALP), procollagen type I N propeptide (PINP), serum cross-linked C-telopeptides of type I collagen (bCTx), and urinary cross-linked N-telopeptides of type I collagen (NTx) [63, 64].