Urinary excretion levels of hydroxylysine glycosides in osteoporotic patients

The urinary excretion levels of hydroxylysine glycosides [Hyl-Gs; O-beta-D-Galactopyranosylhydroxylysine (GH) and 2-O-alpha-D-glucopyranosyl-O-beta-D-galactopyranosylhydroxylysine (GGH)], provide a new index of collagen metabolism. The determination of urinary hydroxylysine glycoside excretion levels was applied to 20 osteoporotic patients and 208 healthy control subjects (69 females and 139 males) in order to evaluate the conditions of bone collagen metabolism. Urinary Hyl-Gs were analyzed by the method of pre-column fluorescent derivatized HPLC. Compared to the age and sex-adjusted control, the urinary excretion levels of hydroxylysine glycosides, especially GH, in osteoporotic patients were significantly higher than in the age and sex-adjusted control, and the urinary GGH/GH ratio was lower. Sixteen of the 20 patients whose Hyl-Gs levels we followed exhibited significantly lower values after 200 d compared to the initial levels. These results suggest that clinical therapeutics affected the bone resorption and, therefore, demonstrated the usefulness of determining urinary excretion levels of Hyl-Gs for evaluating the conditions of bone metabolism.