Do markers of bone metabolism reflect the presence of a high- or low-turnover state of bone metabolism?

Background: A pathophysiological concept of osteoporosis therapy - antiresorptive treatment of high-turnover osteoporosis (e.g. bisphosphonates, raloxifen) and osteoanabolic treatment of low-turnover osteoporosis (e.g. parathyroid hormone) - is clinically and economically reasonable to enable physicians to decide who will benefit most from which drug. Biochemical bone markers in, in serum and urine are frequently used for the diagnosis of high- or low-turnover osteoporosis. We investigated whether bone marker levels reflect the histologically diagnosed high- or low-turnover state of osteoporosis. Material and Methods: 175 bone biopsies of male and female osteoporotic patients (WHO criteria) were histologically classified in high- and low-turnover osteoporosis and associated with bone marker levels in serum and urine. Patients with any osteotropic therapy and with fractures were excluded. Results: There were no significant differences between patients with high- and low-turnover osteoporosis with regards to osteocalcin, DPD crosslinks, alkaline phosphatase, 25-OH vitamin D-3,D- parathyroid hormone and bone mass (spine and hip). Conclusions: Single measurements ofbiochemical bone markers in serum and urine do not allow a valid differentiation between histologically diagnosed high- and low-turnover states of osteoporosis. The therapeutic concept of treating a high-turnover osteoporosis with antiresorptive drugs and a low-turnover state with osteoanabolic drugs requires valid diagnostic criteria for the differentiation between high- and low-turnover state of bone metabolism which can be provided by a bone biopsy but not by single measurements of bone markers.