The major forms of urolithiasis consist of either upper tract stones within the kidneys or ureters (renal stones) or lower tract stones formed within the bladder. These two forms of urolithiasis have distinct differences in etiology, chemical composition, and epidemiological features, and should therefore be considered two separate diseases.

Historical evidence has shown a striking increase in incidence of renal stone disease in more developed countries over the past 100 years. There has been a simultaneous decrease in bladder stone incidence, demonstrating an inverse relationship between the two disorders. Changes in the environment have a profound effect on the epidemiology of human diseases. An unusual example of this interplay is the role of dietary change in the shifting epidemiological pattern from bladder stone to renal stone disease.

Etiology

The large majority of bladder stones occur in young boys from rural or impoverished areas. In these regions, the disorder is known as endemic bladder stone disease. Information from both historical and experimental sources points to a nutritional deficiency during infancy or possibly in utero as the major factor in endemic bladder stone formation. Other less common causes of bladder stone are schistosomiasis (producing bladder wall thickening, stricture, and outlet obstruction) as well as obstruction in elderly males from benign prostatic hypertrophy.

Although deficiencies of vitamin A, vitamin B6, or magnesium have been suggested in endemic bladder stone disease, low intake of animal protein in combination with high intake of grain carbohydrate is more important. Indeed, it seems that whereas low animal protein intake in infancy may cause bladder stone, a high animal protein diet provokes renal stones (Robertson 1978).