OC is a bone-specific 5–8KD protein produced by osteoblasts, and is the most common protein (about 3%) in bones except type I collagen (90%).[5] Clinical studies have shown that CTX, P1NP and OC are moderate positively correlated, and all of them are negatively correlated with bone density.[6] Therefore, the serum level of BTMs should be paid attention to and monitored after the ischemic stroke of aged patients, and anti-bone resorption drugs like alendronate sodium should be used for patients with rapid increasing or high level of BTMs. This evidence concerns the gene CYP27A1 and ischemic stroke.