The interest of biochemical markers of bone turnover for monitoring treatment of postmenopausal osteoporosis

BACKGROUND: Postmenopausal osteoporosis is especially female pathology, whose incidence increases with age. AIM: The purposes of this study are to evaluate the level of bone turnover by the determination of markers of bone formation (PAL, BAP) and marker of bone resorption (CTX) in the osteoporotic women, to study the correlations between bone biochemical markers, clinical parameters and radiological measurements and to assess the interest of biochemical markers therapeutic monitoring after 6 months of antiresorptive treatment. METHODS: The authors report a prospective study of 134 osteoporotic women classified in two groups according to the presence of osteoporotic fracture. Patients of the first group G1 (n=102) with fractures, were treated by the bisphosphonates (risedronate), whereas the ones of the second group G2 (n=32) without fractures, were submited to calcic supplementation and vitamin D. RESULTS: The analyses showed that the femoral and lumbar BMD were statistically lower in the presence of osteoporotic fractures. However, the values of CTX were statistically higher in the patients of G1 group compared to those of the G2 group (0,708 +/- 0,332 ng/ml versus 0,514 +/- 0,225 ng/ml). The CTX were statistically correlated with the femoral and lumbar BMD (r = -0,21, p<0,05 and r= -0,348, p<0,001). The hypovitminosis were observed in 50,98% (52/102) of women with ostéoporotic fractures, whereas it was only 25% (8/32) in women without fractures. After 6 months of treatment by the bisphosphonates, the PAL, the BAP and the CTX have decreased with an average of, respectively, 19%, 46,5% and 62,9%. These variations were significantly more important in G1 group. CONCLUSION: The biochemical markers of bone turnover, in particular those of the resorption (CTX), can predict the postmenopausal woman's bone loss evaluated by BMD, the risk of fractures and the efficiency of the bone treatments.