Epidemiology of urolithiasis in Liège according to morpho-constitutional classification

Background
Stone components are various and influenced by acquired and inherited factors. Hence we describe the distribution of stone composition in Belgium according to age and sex.
Methods
We retrospectively reviewed 1869 urinary stones analyzed between 2010 and 2013 at the laboratory of the CHU of Liège (Belgium). Samples were assessed by infrared spectroscopy, and morphology was used to classify stones in morpho-constitutional types according to Daudon classification.
Results
Among 1869 stones, 69.2% affected men. The prevalence peak was observed between 50–60 years of age in both genders. The main constituent was calcium oxalate monohydrate (54.4%), mainly organized as type Ia (94%). Calcium oxalate dihydrate was found in 19.8% samples, with an equal distribution between types IIa and IIb. Uric acid was the 3rd most frequent constituent in man (10.8%), instead of phosphates in woman (26.6%). Urinary infection may be the main cause of stone formation in 6% of patients. Multiple morphological types were concomitantly identified in 49.3% of stones. The proportion of calcium oxalate dihydrate stones decreased with aging, while monohydrate and uric acid increased in both genders.
Conclusion
This retrospective analysis of urinary stones helps for the first time to characterize the epidemiology of urolithiasis in Belgium.