RESUMO
OBJECTIVES: With the purpose of evaluating the role of oxidative stress (OS) in male idiopatic osteoporosis, we have evaluated plasma total antioxidant capacity (TAC) in patients classified according to age (< 65 or ≥ 65 yrs), with normal hormone values and in age-matched healthy control subjects. PATIENTS AND METHODS: TAC was evaluated with a colorimetric method, using the system metamyoglobin-H2O2 and the chromogen ABTS; the latency time (LAG, sec) in the appearance of ABTS radical species is proportional to antioxidant content of the system. RESULTS: We found slightly increased LAG values in middle-aged patients, compared with age-matched controls, probably expression of a compensatory mechanism to OS; on the contrary aged patients showed significantly lower LAG values in comparison with age-matched controls, suggesting a defective compensatory mechanism and, therefore, a risk for oxidative damage. CONCLUSIONS: OS could be a possible mechanism underlying male osteoporosis, both in middle-aged and aged patients, but compensatory mechanisms seem to be defective in the last group.