[Basic aspects of bone metabolic markers].

Bone formation and bone resorption are altered in most metabolic bone diseases. Recent advances in measurement of bone metabolic markers arrows as the non-invasive investigation of bone metabolic balance. The rate of formation or degradation of the bone matrix can be assessed by the measurement of bone specific proteins and it's degradative products. Among the posturated products, osteocalcin, carboxy-terminal propeptide of type I collagen (PICP) are considered to be more specific indices to know the osteoplastic function. On the other hand, pyridinoline or deoxypyridinoline in urine strongly reflects bone resorption rate. However some criticisms still exist in the evaluation of serum or urinary levels of bone metabolic markers, especially in formation markers. In adults, bone formation marker such as osteocalcin negatively correlated with their bone mineral density. On the other hand, in children, osteocalcin positively correlated with height velocity. Therefore we have to pay special attention to dysfunction of osteoblast, such as retarded calcification in evaluation of serum level of bone formation markers.