[Bone and bone related biochemical examinations. Bone and collagen related metabolites. Bone resorption marker;...

The determination of C-terminal telopeptide of type I collagen degradation products (CTX) was made by using the monoclonal antibody recognizing the eight amino acids that are specific for alpha1 chain of type I collagen. CTX values show a diurnal variation, with a nadir from 1 to 11 o'clock in the afternoon, increase at midnight with peaks from 2 to 8 o'clock in the morning. The levels of CTX at peaks are approximately twice those at a nadir, which implies the sampling of serum and urine should be made at an identical time at each patient. There were significant correlations in patients on hormone replacement therapy (HRT) between lumbar spine bone density at 2-yr and percent changes of serum, or urinary CTX at 3-month and the percent change of CTX at 3-month alone could predict the percent change of lumbar spine bone density at 2-yr.