[Composition of renal stones currently observed in non-industrialized countries].
Up until relatively recently, renal stones in developing countries were considered to be very different from those observed in industrialized countries, essentially characterized by the predominance of phosphate and urate stones, while the predominant stones in industrialized countries are calcium oxalate stones. To verify whether this difference in the epidemiological profile is still observed today, we analysed renal stones collected in various regions of the globe and compared their composition to that of stones observed in France.


METHODS
1,042 stones were collected between 1991 and 2000 from 14 different countries or geographical zones: Sub-Saharan Africa (Cameroon, Mali, Senegal), North Africa (Algeria, Morocco, Tunisia), South America (Brazil, Paraguay), Asia Minor (Pakistan, Turkey), Far East (China, Laos, Vietnam) and French Polynesia (Tahiti). Stones were analysed by infrared spectrophotometry. The composition of these stones was compared to that of 24,706 stones collected in France over the same period and analysed according to the same protocol.


RESULTS
Overall, the proportion of calcium oxalate stones was the same in adults in France and in developing countries (men: 75.7% contre 72%; women: 59.8% contre 56.3%), but was higher in children in non-industrialized countries (boys: 52.6% contre 31.8% in France; girls: 67.8% contre 48.8% in France, p<0.0001). The frequency of calcium phosphate stones was particularly low in boys in developing countries (8.3% contre 45.1% in France, p<0.0001) andfrequency of purine stones was higher in boys (21.3% contre 5.2% in France, p<0.0001) and in girls (13.6% contre 4.3% in France, p<0.05). Major differences were observed according to continent and region; struvite was present in 42.9% of stones in women in Sub-Saharan Africa contre 13% in South America and 2.7% in Asia Minor. Purines were 4 times more frequent in Tahitian men than in North African men. Calcium phosphate stones were 10 times less frequent in men in Asia Minor than in the Far East.


CONCLUSIONS
The epidemiology of renal stones is continuing to change all over the world towards a predominance of calcium oxalate stones, which is now generalized. Major differences in the frequency of the other constituents, particularly purines and struvite, reflect particular eating habits and infectious risk factors specific to certain population.
Daudon
Michel
M
Laboratoire Cristal, Service de Biochimie A, Hôpital Necker, Paris, France. michel.daudon@nck-ap-hop-paris.fr
Bounxouei
Bounthaphany
B
Santa Cruz
Francisco
F
Leite da Silva
Sônia
S
Diouf
Boucar
B
Angwafoo
Fru F
FF
Talati
Jamsheer
J
Desrez
Gonzague
G
D000328:Adult; D002648:Child; D003906:Developing Countries; D005260:Female; D005602:France; D006801:Humans; D007669:Kidney Calculi / Q000737:chemistry* / Q000453:epidemiology; D008297:Male; D008875:Middle Aged