American and Brazilian Children With Primary Urolithiasis: Similarities and Disparities.

Objectives. Considering the differences in location, socioeconomic background, and cultural background, the aim of this study was to try to identify possible factors associated with the increased incidence of urolithiasis by comparing American and Brazilian children with stones. Methods. Data of 222 American and 190 Brazilian children with urolithiasis were reviewed including age, gender, body mass index, imaging technique used (ultrasound and computed tomography), and 24-hour urine volume and chemistries. Results. There were no differences between age and gender at diagnosis. Brazilian children were leaner but in no population did obesity rate exceed that of the general population. Ultrasound was most commonly used to diagnose stones, even more so in Brazilians. Decreased urine flow was more common among Americans (P = .004), hypercalciuria among Brazilians (P = .001), and elevated Ca/citrate ratio among Americans (P = .009). There were no differences between the groups in the frequency of hypocitraturia, hyperuricosuria, absorptive hyperoxaluria, and cystinuria. Conclusions. Despite some differences between the populations, the leading causes of urolithiasis among both were "oliguria," hypercalciuria, and high Ca/citrate ratio. In neither country was obesity the reason for the increase in incidence of urolithiasis, nor was the use of computed tomography. The similarities between the 2 populations call for combining efforts in addressing the leading causes of pediatric urolithiasis.