NEW BIOCHEMICAL MARKERS OF BONE-RESORPTION IN THE STUDY OF POSTMENOPAUSAL OSTEOPOROSIS

We performed a comparative study on the sensitivity of the determinati on of several biochemical markers of bone resorption: urinary calcium/ creatinine, free pyridinolines (F-Pyr), free deoxypyridinoline (F-Dpyr ), carboxyterminal telopeptide of collagen I (CTX) and amino-terminal crosslinked telopeptides of collagen I (NTX) in the study of postmenop ausal osteoporosis. The study included 19 untreated osteoporotic postm enopausal women, aged 59 plus minus 6 years, range 46-70 and 16 health y control postmenopausal women, aged 56 plus minus 7 years, range 48-7 0 years. The following bone markers were determined in 2-h fasting uri ne samples: calcium/creatinine (atomic absorptiometry), F-Pyr (ELISA,M etra), F-Dpyr (ELISA,Metra), F-Dpyr (ELISA, Metra),CTX (Crosslaps, Cis bio International) and NTX (ELISA, Osteomark, OSTEX). Values of aa ma rkerswere expressed as urinary creatinine (Cr) ratios. We found a sign ificant increase in all the studied biochemical markers of bone resorp tion in osteoporotic patients with respect to control women. Areas und er receiver operating characteristic (ROC) curves corresponding to F-P yr/Cr, Calcium/Cr, NTX/Cr, CTX/Cr and F-Dpyr/Cr were 74%, 75%, 93.4%, 95.7% and 96% respectively. There were no significant differences amon g the areas of the ROC curves corresponding to NTX, CTX and F-Dpyr, bu t areas under urinary calcium and F-Pyr were significantly lower. Amon g the biochemical markers of bone resorption studied, F-Dpyr, CTX sand NTX presented the best discrimination between osteoporotic and contro l women. F-Dpyr/Cr sensitivity was 79% with a specificity of 1005, CTX /Cr sensitivity was also 79% with a specificity of 100% and NTX/Cr sen sitivity was 52% with a specificity of 100%.