Objective: Due to rapid economic development over the past four decades, urinary stone components may have changed in Taiwan. We studied the changes in urinary stone components over time and the possible association with dietary changes during the same period.
Materials and methods: From 1956 to 1999, 9,715 urinary calculi were collected at a single institution and analyzed using polarizing microscopy. Dietary information was obtained from an official national report. Linear regression was used to analyze the possible correlation between the change in stone components with daily consumption of animal protein, vegetable protein, and lipid.
Results: Eleven distinct components were identified. Calcium oxalate (Jensen type I stone; found in sterile, acidic urine) was found most frequently (87.3%), and its incidence increased gradually with time. However, the incidence of Jensen type III stone (caused by metabolic abnormality) gradually decreased from 1956 to 1999. The male to female ratio among subjects was 2.3:1, and the modal age was in the forties. Female patients were more likely to suffer from type II stones (found in infected, alkaline urine), whereas type I and III stones were more prevalent in males. Among the dietary components, consumption of animal and vegetable proteins and lipid increased significantly during the same period, and appeared to be coincident with the increased incidence of type I stones during the study period.
Conclusions: Patterns of urinary tract stones in Taiwan have progressively changed in the past four decades and are now similar to those in western populations. The incidence of type I stones has increased during the past four decades, which may reflect the Westernization of dietary habits in Taiwanese during the same period.