Abstract
We read with great interest the recent article by Grant et al. 1 who retrospectively collected data of 4339 kidney stones from 7 representative states. The authors concluded that kidney stone composition does not vary widely between states within the United States. Uric acid stone was found more often from Florida and incidence increases with age. The authors should be congratulated for performing a scarce study, which evaluated different ages and states to determine whether kidney stone composition changes within the United States.
A previous study by Daudon and colleagues 2 reported variation in stone composition in Europe. The study confirmed that calcium oxalate dihydrate was five times more common in younger people than in elderly, and declined 3% to 5% for each decade from 20 to 80 years. Calcium oxalate monohydrate was the most common component, and reached a peak between 40 and 70 years. Calcium phosphate was the dominant component (40%) in patients up to 10 years.
Kidney stone is a highly prevalent disease worldwide with 6.4% prevalence rates in China, and the recurrence is up to 50% within 10 years. 3 A previous study indicated that geographical differences play an important role in the prevalence rates of kidney stone, for example, the south and southwest parts more prevalent than the north and northwest regions of China. Moreover, dietary habits and lifestyle may lower the risk of kidney stone formation, such as consumption of more tea, legumes, and fermented vinegar. 3
Stone composition is influenced by many variables, including age, economic, genetic, regions, climate, metabolic syndrome, and dietary factors. 4 Therefore, prospective multicenter studies are lacking to better understand these factors affecting stone formation. Moreover, understanding the impact of associated conditions that are necessary will contribute to evaluation, treatment, and prevention of kidney stone.