Chapter 60 - Biochemical Markers of Bone Turnover in Osteoporosis

Abstract

This chapter reviews the recent development in bone marker technology and also discusses the use of markers for the management of osteoporosis. There are basically two types of biomarkers for bone remodelling: for bone formation and for bone resorption. Biomarkers for bone formation consists of skeletal alkaline phosphatase (ALP), osteocalcin, and procollagen type I propeptides (PICP). ALP activity may provide information of bone metabolism within specific bone envelopes. Serum total alkaline phosphatase activity is the most commonly used marker of bone formation, but for the above reasons, it lacks sensitivity and specificity. PICP concentrations correlate weakly with histological bone formation in patients with vertebral osteoporosis. Biochemical markers of bone resorption consists of tartrate-resistant acid phosphatase, free pyridinoline and deoxypyridinoline, C-terminal cross-linking telopeptide of type I, N-terminal and C-terminal (S-CTX) crosslinking telopeptide of type I collagen, and bone sialoprotein. In osteoporosis, bone turnover markers have been suggested to predict the rate of postmenopausal bone loss, to predict the occurrence of osteoporotic fractures, and to monitor the efficacy of treatment, especially anti-resorptive therapy (hormone replacement therapy, bisphosphonates, and calcitonin). It has also been suggested that measurement of bone turnover before treatment might be useful to select the type of therapy (anti-resorptive or bone stimulating agent) and to predict the amplitude of the response to estrogen and bisphosphonate treatment.