Evaluation of different biochemical markers of bone turnover as a diagnostic tool for osteoporosis in postmenopausal women

ABSTRACT

Osteoporosis is a major global health problem affects mainly elderly and postmenopausal women with increased risk of bone fractures. The value of different biochemical markers of bone turnover as diagnostic tool for osteoporosis is still debated. The aim of this study is to assess the value of different biochemical markers of bone turnover as a diagnostic tool for osteoporosis in postmenopausal women. We measured fasting urinary calcium [Uca], total ALP, inorganic phosphorus [Pi], urinary deoxypyridino-line [DPD], carboxyterminal telopeptide of collagen type I [ICTP] and serum N-terminal telopeptide [NTX] in 40 postmenopausal females [diagnosed by DEXA as osteoporotic, | mean age, 60.2 years], 16 preimenopausal non-osteoporotic females [mean age, 39.1 years] and 24 healthy controls [mean; age, 29.2 years]. The postmenopausal osteoporotic group showed significantly higher levels of ALP, DPD, NTX and ICTP compared to controls [p<0.001] and only ALP was significantly higher in preimenopausal group compared to controls [p<0.001]. However, there was no significant difference of Uca and Pi among the three groups. On comparing peri and postmenopausal groups together, DPD, NTX and ICTP were the only markers that clearly discriminate the two groups being higher in the osteoporotic postmenopausal group. There were significant negative correlations between bone mineral density [BMD] and each of ALP, DPD, NTx, and ICTP. The clinical utility of DPD, NTx and ICTP in identifying patients with osteoporosis was assessed by ROC [receiver operating characteristic] curve analysis. This revealed that the best diagnostic cut-off level for DPD was 6.8nM DPD/mM creatinine. This gave a diagnostic sensitivity of 100% and specifity 100%, whereas NTx at a level 17.0 nM BCE had a diagnostic sensitivity of 100% and specifity of 98%. Regarding ICTP at cut-off level of 3.6 microg/L its sensitivity was 88% and specifity was 65% which considered the lesser better sensitivity and specifity among the three studied parameters