Clinical usefulness of biochemical resorption markers in osteoporosis

We have evaluated three commercial assays for collagen cross-links, two uri ne assays and a recently developed serum assay, as markers of bone turnover in 30 postmenopausal women with osteoporosis during their first year of tr eatment with the anti-resorptive drug alendronate. Before treatment, urine free deoxypyridinoline crosslinks (Dpd), urine N-te lopeptide crosslinks (NTx) and serum C-telopeptide (CTx) values were within postmenopausal reference ranges. After 3 months' treatment the decrease in NTx and CTx was greater than that of Dpd (-50%, P < 0.0001 and -48%, P < 0 .0001, compared with -11%, NS), as it was after 6 months (-51%, P<0.0001, a nd -57%, P<0.0001, compared with -19%, P<0.01). The decrease in resorption markers after 6 months was significant in 23% (Dpd), 66% (NTx) and 66% (CTx ) of individuals. Neither baseline resorption marker values nor the per cen t change after 6 months' therapy correlated with bone mineral density chang e (BMD) at either lumbar spine or femoral neck after one year's therapy, ex cept baseline Dpd and lumbar spine BMD (P < 0.01). We conclude that NTx and serum CTx were more sensitive markers of bone turnover suppression by alen dronate, but only baseline Dpd was useful in the prediction of individual b one density response after one year.