Biomarkers of bone health and osteoporosis risk

Abstract

The assay features of biochemical markers of bone turnover have markedly improved in the past few years. The most sensitive and specific markers of bone formation include serum bone alkaline phosphatase, total osteocalcin (including the intact molecule and the large N-mid fragment) and the procollagen type I N-terminal propeptide assay. Among the various markers of bone resorption, measurements of the urinary excretion of N-and C-terminal cross-linked telopeptides) and of serum C-terminal cross-linked telopeptides are the most sensitive and specific. Markers of bone turnover can be used to predict the rate of bone loss in postmenopausal women and can also be used to assess the risk of fractures. In osteoporosistreatment studies (with alendronate, risedronate, raloxifene) markers of bone turnover appear even more strongly associated with fracture risk reduction than bone mineral density (BMD). These observations support the use of markers of bone turnover as surrogates for fracture risk reduction, perhaps even more so than BMD. Bone markers can also be used to monitor the efficacy of antiresorptive therapy such as hormone-replacement therapy, raloxifene and bisphosphonates in individual patients. Furthermore, they have also proved to be helpful in monitoring the response to nutritional interventions and have the advantage over BMD in that they provide information about mechanism of effect and changes are often observed much more rapidly.Bone turnover markers: Bone mineral density: Bone health: Osteoporosis Osteoporotic fractures have a considerable impact on the individual and on health economics. There is a substantial increase in mortality and morbidity, particularly after a hip fracture; 10-20 % more women die subsequent to a hip fracture than would be expected for their age, and for those who survive £ 50% cease to be able to live independently (1) . In health economic terms it is estimated that there are >160 000 osteoporotic fractures per year in the UK alone, which cost the National Health Service £1 . 7 · 10 9 . Antiresorptive therapies are now available that have been shown to rapidly reduce fracture incidence even in elderly women (2)(3)(4)(5) . However, in developing a fracture prevention strategy it is important to be able to identify those women at greatest risk of a fracture.It is now well established that fracture risk is higher in women with low bone mineral density (BMD), with a decrease of 1 SD in BMD leading to a doubling of the risk of fracture (6) . However, there are numerous other risk factors for osteoporotic fractures and a WHO working party has been developing an approach for the estimation of 10-year fracture risk based on these factors (7) . Recently, attention has turned to the role of biochemical markers of bone turnover as predictors of fracture. Bone turnover may predict fracture in two ways: (a) via BMD, since high bone turnover is associated with low BMD (8) ; (b) independently of BMD, since increased bone turnover has a detrimental effect on bone microarchitecture and fragility ...

Effects of vitamin E on bone turnover markers among US postmenopausal women

“…(52) Both of these markers are among the most sensitive and specific markers of bone turnover. (30) In the years 1999-2001, BAP was measured using the HybritechTandem-MP Ostase Immuno Enzymetric assay (Hybirtech Inc., San Diego, CA, USA) and in 2002, BAP was measured using the Beckman Access Ostase assay (Beckman Coulter, Inc., Fullerton, CA, USA). Adjustments were made to correct for this change of methods.…”

“…Several studies have shown that baseline elevated BAP and NTx, or decreased BAP and increased NTx are predictors of BMD loss and increased fracture risk in postmenopausal women. (30,32,95) The NHANES 24-hour dietary recall represents food intake the day prior to the blood and urine collection day for analysis of BTMs, and may reflect the short-term effect of diet on bone metabolism. Serum tocopherol concentrations reflect short-term dietary intake (28,29) and are also suitable for the examination of the relations between short-term surrogates of bone status such as BTMs.…”

High-calcium, vitamin D fortified milk is effective in improving bone turnover markers and vitamin D status in healthy postmenopausal Chinese women

“…8,9 In our study, HCM significantly impacted on markers of bone resorption and formation. These markers can be predictive of future bone loss 38 and future risk of fracture 36 independent of BMD, 39 as high turnover can affect trabecular architecture and increase the incidence of perforation, thereby reducing bone strength. A study supplementing 9605 community-dwelling elderly adults (466 years of age) with 1000 mg calcium and Values are given as least-squares mean (s.e.).…”

Bone turnover assessment: a good surrogate marker?

“…pyrophosphate which inhibits mineral crystallizations and acts as a calcium-binding protein. It has a half-life of 1-2 days making it less sensitive to circadian variation, and it is not influenced by renal dysfunction (19).…”