[Clinical usefulness of biochemical markers of bone turnover in early postmenopausal women: two years longitudinal study].

Background And Objective: Many studies have been performed on the ability of bone turnover markers (BTM) for the prediction of bone loss and to assess the correlation of BTM with bone mineral density (BMD). However, the results from these studies have been mixed. The aim of this study was to assess the usefulness of BTM to predict bone loss and to analize the correlation of BTM with BMD in early postmenopausal women.

Subjects And Method: 183 healthy women, aged 50 to 55 years, with natural menopause of 6 to 36 months were randomly selected. We measured bone alkaline phosphatase (BALP), intact osteocalcine (OC) and C-telopeptide (sCTx) in serum, and calcium, deoxipiridinoline (DPD) and N-telopeptide (NTx) in urine. Bone densitometry of the spine (L(2)-L(4)) was performed at the start of the study and two years later. Student t test, ANOVA, chi2 test and ROC curves were used for the statistical analysis.

Results: Bone markers, mainly OC and CTx, correlated with BMD and discriminated osteoporosis, osteopenia and normal bone mass (p < 0.001). According to the ROC curves, OC had a sensitivity of 77.8% and specificity of 80.6% for the diagnosis of osteoporosis and sCTx, 83.3% and 74.5%, respectively. Regarding the relation to bone loss, only sCTx showed difference between the lowest and the highest quartile (p = 0.042), but we did not find an association between high turnover and fast bone losers.

Conclusions: Bone markers, mainly OC and sCTx, are useful for identification of osteoporotic and osteopenic early postmenopausal women. However, regarding the bone loss, only CTx has a weak predictive value.