Biochemical markers of bone turnover

Background: Osteoporosis in many countries has reached epidemic proportions . This has stimulated the development of biochemical markers to assist in t he assessment of osteoporotic risk and in monitoring the efficacy of treatm ent. Biochemical markers of bone turnover are products released from osteob lasts and osteoclasts or collagen breakdown products. Markers: Markers of b one formation include bone-specific alkaline phosphatase (BAP), osteocalcin (OC) and procollagen peptides. All of these can be measured easily by immu noassay techniques. Of these markers, OC has been extensively studied. Howe ver, OC undergoes in vitro degradation, thus, assay results are variable. B AP, on the other hand, is much more stable and shows less within-person bio logical variation. Bone resorption markers include tartrate-resistant acid phosphatase (TRAP) and collagen breakdown products, such as pyridinium cros s-links, galactosyl hydroxylysine and cross-linked telopeptides, such as CT x and NTx. Of these, deoxypyridinium (DPD) has been extensively studied. DP D shows diurnal variation and the within-individual biological variation is large. Of the newer assays, NTx appear to show large differences at menopa use. Conclusions: Thus, serum BAP and DPD or NTx are the current choice of bone markers. (C) 2001 Elsevier Science B.V. All rights reserved.