Biochemical markers of bone turnover

Abstract

Invasive techniques measuring bone turnover have provided useful information but all have limitations. Histomorphometry of the iliac crest provides unique information on the rate of formation both at the cell and at the tissue levels, allows to measure the activation frequency of remodeling units but the assessment of bone resorption is less accurate. In addition, measurement of bone turnover is limited to a small area of the cancellous and of the cortico-endosteal envelope which may not always reflect bone turnover of other sites of the skeleton (Delmas 1988). Calcium kinetic studies have allowed quantification of the increase of bone turnover after the menopause but measurement of calcium accretion rate—an index of bone formation- may be inaccurate in elderly women (Eastcll et al. 1988). Finally the whole body retention of labeled bisphosphonates (WBR), a marker of bone turnover and bone formation has not proved to be very sensitive (Thomsen et al. 1987). These limitations, in addition to the need of non-invasive techniques that can be applied more widely and repeated several times in a single patient, provide the rationale lo develop markers of bone turnover to be measured in blood and urine.