Comparison of metabolic risk factors in patients with recurrent urolithiasis stratified according to age and gender.

OBJECTIVE: Little is known regarding the metabolic features associated with aging and gender in urolithiais patients. We compared the metabolic characteristics among 3 generations (young, middle-aged and old) with recurrent calcium-containing urinary stones.

METHODS: One hundred and eighty-one patients with recurrent calcium-containing stones, including 71 patients aged </=45 years (group 1), 71 patients aged 46-60 years (group 2) and 39 patients aged >/=61 years (group 3), were investigated by metabolic evaluation. The frequencies of metabolic abnormalities, the value of each urinary constituent and the supersaturation index (AP(CaOx) index) were compared among subgroups of the 3 generations, containing both males and females.

RESULTS: The number of metabolic abnormalities was the greatest in group 1, followed by group 2 and group 3. Hyperoxaluria was the most common abnormality in each group. Group 1 females showed a lower frequency of hypocitraturia than group 3 females. This was the only characteristic that showed a significant difference between the groups. Urinary calcium excretion was significantly greater in group 1 than in group 3. Urinary citrate excretion and the AP(CaOx) index were significantly higher in group 1 than in group 3 in females. Male patients had a significantly higher number of metabolic abnormalities than female patients, especially in group 1.

CONCLUSION: Multiple metabolic abnormalities, particularly a high calcium excretion appear to be crucial factors in the development and recurrence of urolithiasis in young patients. Low urinary citrate excretion could play an important role in the occurrence of urolithiasis in elderly females.