ACP5 and osteoporosis: After 3 months of treatment, we evaluated their ratio of serum bone‐specific tartrate‐resistant acid phosphatase to bone‐specific alkaline phosphatase (TRACP‐5b/BAP), which is widely used for evaluating bone turnover in postmenopausal patients with osteoporosis in Japan because their minimum significant changes are smaller than other bone turnover markers such as carboxy‐terminal collagen cross‐links (CTX) or N‐terminal propeptide of type I procollagen (P1NP) and thus, accurately reflect bone turnover.