CYP27A1 and Osteopenia: Using stored plasma samples from a previous randomized controlled clinical trial (RESHAW) of resveratrol supplementation in postmenopausal women exhibiting mild osteopenia, we have studied changes in plasma aminoterminal proCNP (NTproCNP) and concurrent change in bone turnover markers of formation (osteocalcin [OC] and alkaline phosphatase [ALP]) and resorption (C‐terminal telopeptide type 1 collagen [CTX]) with bone mineral density (BMD) over a 2‐year period of study in 125 subjects.