[Biological markers of bone metabolism].

During the last few years non-invasive methods to measure bone metabolism have been the object of intensive studies, chiefly because of the need for sensitive and specific markers to be used in the exploration of osteoporosis. Bone formation can be evaluated by assays of serum alkaline phosphatase, osteocalcin and collagen extension peptides. Bone resorption can be quantified by assays of urinary hydroxyproline and urinary pyridinoline excretion, and by assay of tartrate-resistant acid phosphatase in plasma. These markers have different sensitivity and specificity. At present, serum osteocalcin and urinary pyridinoline are the most effective markers, notably to evaluate bone metabolism in menopausal women and in patients with vertebral osteoporosis. In the near future a battery of tests based on a combination of the most effective markers will probably be used to study the complex abnormalities of bone metabolism which occur in bone diseases, and in particular in osteoporosis.