Epidemiology of urolithiasis.

The epidemiology of urolithiasis differs according to geographical area and historical period: changing socio-economic conditions have generated changes in the incidence and type of lithiasis in terms of both the site and the physical-chemical composition of the calculi. Reno-ureteral calculosis typical of adult age and featuring mainly calcium oxalate and phosphate is currently more frequent in economically developed countries, where the prevalence rate hovers between 4% and 20% and the annual incidence of hospitalization for calculosis ranges from 0.03 to 0.1%. On the contrary "primitive" vesical calculosis is fairly widespread in Asia, with calculi composed of ammonium urate and calcium oxalate. Vesical calculosis, due to malnutrition in the very early years of life, is currently frequent in huge areas of Turkey, Iran, India, China, Indochina and Indonesia, although the incidence is decreasing in proportion as social conditions gradually improve. At the beginning of the 20th century primitive vesical calculosis was relatively frequent in Europe also, but in the course of the last 100 years, there has been a gradual decrease in its incidence, while the reno-ureteral calculosis has become more common. This trend definited as "stone wave" has been explained in terms of changing social conditions and the consequent changes in eating habits. In Europe, Northern America, Australia, Japan, and, more recently, Saudi Arabia affluence has spread to all social classes, and with it the tendency to eat "rich" food in large quantities. Calcium oxalate and/or phosphate stones account for almost 70% of all renal stones observed in economically developed countries. The prevalence of this type of stones varies considerably on account of environmental factors, especially dietary intake and lifestyle, while radiolucent and infection stones seem to be less influenced by environmental conditions. In the seventies the pathogenetic role for calcium oxalate stones of a diet rich in proteins, refined carbohydrate and sodium has become evident, while the effect of alimentary calcium and oxalate is still debated. However, the concurrence of a genetic predisposition seem to be crucial for calcium stone formation. In fact the importance of family history for idiopathic calcium stone disease is clearly demonstrated, although little is known about the metabolic alterations underlying this predisposition and their genetic transmission mechanisms.