Patients on a bisphosphonate holiday should be closely monitored for a new fracture or accelerated bone loss evident on a DXA scan, especially after being off therapy for 2 years or more. During therapy with an antiresorptive drug, such as a bisphosphonate, bone turnover is suppressed as evidenced by low serum or urinary levels of (fasting) N-telopeptide cross-links (< 40 nmol / L) or C-telopeptide cross-links.