URINARY-EXCRETION OF PYRIDINOLINE AND DEOXYPYRIDINOLINE - CIRCADIAN-RHYTHM IN HEALTHY PREMENOPAUSAL WOMEN

Urinary cross-linking amino acids (pyridinoline and deoxypyridinoline) are used as biochemical markers of bone resorption. Therefore, the study of their diurnal behavior might provide information on whether circadian variability could be observed in bone remodelling. We showed a significant circadian rhythm of both urinary pyridinoline and deoxypyridinoline in healthy premenopausal females with higher concentrations at 05.35 and 0457, respectively. The reported observations suggest an increased rate of bone resorption during the night in subjects living on a usual day-night schedule. Moreover, these findings focus the attention on the importance of the sampling time for the comparison of data from different studies and from patients with different pathological conditions.