Urine and serum bone turnover markers are either enzymes or
proteins produced during bone formation or breakdown. Bonespecific
alkaline phosphatase, osteocalcin and procollagen type 1
propeptides are examples of bone formation markers. Hydroxypyridinium
crosslinks of collagen pyridinoline and deoxypyridinoline,
C-terminal crosslinking telopeptide of type 1 collagen and Nterminal
crosslinking telopeptide of type 1 collagen are examples of
bone resorption markers. Increased concentrations of bone resorption
markers (≥2 standard deviations above the premenopausal
range) have been shown in some studies to predict fracture risk;
however, results have been inconsistent.19 Although not diagnostic,
these tests my be helpful in identifying accelerated bone turnover
and increased fracture risk or in monitoring response to therapy.