A comparative study on biochemical markers of bone collagen breakdown in post-menopausal women.

The aim of this study was to compare urinary galactosylhydroxylysine (GHyl) and deoxypyridinoline (d-Pyr) as biochemical markers of bone resorption in post-menopausal women treated and untreated with estrogen and cyclic etidronate. Fasting urinary GHyl, D-Pyr, pyridinoline, serum osteocalcin and total alkaline phosphatase were measured in three subgroups, i.e. post-menopausal women undergoing hormone replacement therapy, untreated post-menopausal women and post-menopausal women with low BMD treated with disodium etidronate. The results indicated that GHyl did not significantly discriminate between untreated post-menopausal women and estrogen replated ones unless an osteoporotic untreated group was selected. d-Pyr and GHyl showed similar performances when their values after bisphosphonate treatment were compared to those found in untreated post-menopausal women, thus suggesting that both markers were equal in their ability to detect the bone response to cyclic etidronate administration. This observation further proves the statement that GHyl is prone to confounding factors under estrogen therapy but it is adequate as is d-Pyr in monitoring the bone response to bisphosphonate treatment.