To evaluate the possible role of being overweight on stone-forming risk factors in children.

A total of 94 children (43 boys and 51 girls, male/female ratio 1:1.8) who were taking no medication or dietary modifications before treatment were included in the study. After a detailed stone disease history, the systolic and diastolic blood pressures were precisely measured and recorded for all patients. The body mass index, 24-hour urine values, and serum stone-forming risk parameters were evaluated in 44 overweight (17 boys and 27 girls; group 1) and 50 normal (26 boys and 24 girls; group 2) children. The results of each group were compared using the Wilcoxon rank sum test.

The evaluation of the stone-forming risk factors in both groups revealed that the overweight status might be responsible for the increased excretion of these substances in such children. Most of the children in group 1 demonstrated hypocitraturia and hyperoxaluria (9/44, 20.5%) compared with the patients in group 2. Although the mean urinary oxalate level was 0.74 ± 0.81 mg/kg/24 h for boys and 0.69 ± 0.72 mg/kg/24 h for girls in group 1, relatively lower values were noted in group 2 (0.42 ± 0.52 and 0.45 ± 0.57 mg/kg/24 h for the boys and girls, respectively). Similarly, the children in group 1 had elevated mean urinary calcium and lower citrate excretion compared with the group 2 patients.

Overweight status in children might be associated with an elevated risk of stone formation in both sexes owing to the alterations in urine composition. Obese children could be more prone to stone formation, and they should be evaluated and followed up for this aspect.