BGLAP and Osteopenia: Surveillance with dual-energy X-ray absorptiometry (DXA) every 1–2 years and monitoring of bone turnover markers (osteocalcin, procollagen 1 N-terminal propeptide [P1NP], C-terminal telopeptide [CTX]) are recommended, with bisphosphonate therapy considered in the event of progression to osteopenia or osteoporosis (31, 31).