Sex- and age-related composition of 10 617 calculi analyzed by infrared spectroscopy.

A series of 10 617 calculi were analyzed by stereomicroscopy and infrared spectroscopy. This first study of French calculi was compared with large series in the literature. That the frequency of pure calculi was the lowest ever observed can be related to the methodology routinely used in our laboratory, which includes microsampling. We described more than 70 components among the 10 617 calculi. The overall sex ratio male to female patients was high (2.27) and increased over the period 1981-1993. Calcium oxalate was the most frequent component (86.48%), followed by calcium phosphate (79.75%) and purines (18.64%). We found a low occurrence of "infection" stones. The sex ratio was related to stone composition and differed according to the main component. For instance, calcium oxalate dihydrate (COD) was more frequent in men than in women, with a sex ratio of 4.97 versus 2.57 for calcium oxalate monohydrate (COM). On the contrary, calcium phosphate was more frequent in female patients (sex ratio 0.72 versus overall ratio). The high frequency of COD calculi (23.17%) suggests that hypercalciuria is particularly frequent in French patients susceptible to stone formation. For each main component, a specific profile was observed in relation to the sex and age of the patients with stones.