Bone turnover markers: understanding their value in clinical trials and clinical practice

Abstract

While bone mineral density (BMD) by dual-energy X-ray absorptiometry is the primary method of determining fracture risk, assessing bone turnover may add valuable information for the management of patients with low bone mass. Bone turnover markers (BTMs) are used in clinical trials where they can provide essential information on the biological efficacy of osteoporosis treatments. In such population-based studies, BTMs can predict fracture risk independent of BMD. When combined with BMD, they improve the fracture risk estimate above and beyond BMD alone in postmenopausal osteoporotic women. Since changes in bone turnover after the initiation of therapy with bone resorption inhibitors occur much more rapidly than changes in BMD, treatment efficacy could, in theory, be determined within weeks of using BTMs. However, such predictive value is limited by the large biological variability of these biochemical markers, even though newer automated methods have reduced their analytical variability. Consequently, widespread adoption as a means of predicting treatment efficacy in fracture prevention for individual patients cannot yet be recommended. BTMs may be useful for monitoring adherence to antiresorptive therapy and may aid in identifying patients for whom antiresorptive therapy is most appropriate. Thus, although BTMs are currently confined to clinical research applications, further improvement in assay precision may extend their diagnostic value in clinical settings.

Serum Osteocalcin as a Diagnostic Biomarker for Primary Osteoporosis in Women

“…Lately, bone turnover biomarkers came into vogue to assess bone turnover rate and monitoring of treatment response in osteoporosis. Osteocalcin, also known as bone gamma-carboxyglutamic acid-containing protein (BGLAP) is secreted by osteoblasts during bone formation phase of bone remodeling [6,7]. In osteoporosis, generally there is a deficiency of calcium and phosphorus level and since osteocalcin is a calcium dependent biomarker and has a strong affinity with bone matrix (hydroxyapatite) responsible for mineralization of bone.…”

Postmenopausal osteoporosis treatment with antiresorptives: Effects of discontinuation or long-term continuation on bone turnover and fracture risk—a perspective

“…Elevated levels of biochemical BTMs in untreated patients have been reported to predict fracture (1,(10)(11)(12)(13) independent of BMD, (12,(14)(15)(16) in part because they reflect stress risers in cancellous bone. A significant association between treatmentinduced changes in BTMs at 3 to 6 months and subsequent fracture risk reduction has also been demonstrated, (17) suggesting that changes in bone turnover per se affect bone strength and fracture risk.…”

Gingival crevicular fluid levels of prolidase and alkaline phosphatase in periodontitis

“…It is characterized by destruction of periodontal tissues. Markers of bone formation are proteins revealing osteoblast activity like products of collagen synthesis, matrix proteins or osteoblastic enzymes 1,2 . Alkaline phosphatase (ALP) is a glycoprotein, which functions as a phospho-hydrolytic enzyme, is a calcium-and phosphate-binding protein.…”