From hypercalciuria to hypocitraturia--a shifting trend in pediatric urolithiasis?

We analyzed the metabolic abnormalities in children with urolithiasis, and the relationship between diet and hypocitraturia.

A single center, retrospective analysis was conducted in all children with renal and/or ureteral calculi seen at our Multidisciplinary Stone Clinic between January 2010 and July 2011. Data at presentation were extracted from the clinical database.

We analyzed 63 children (37 girls) with urolithiasis with a mean age of 13.43 ± 4.61 years. Of the 45 patients with 24-hour urinalysis, a metabolic risk factor was present in 68.9%, with hypocitraturia (58.1%) and hypercalciuria (48.3%) being the most common. Children with isolated hypocitraturia had lower urinary magnesium and potassium levels (1.06 ± 0.62 mg/kg and 0.53 ± 0.24 mmol/kg per day) than those with no metabolic abnormalities (1.72 ± 0.61 mg/kg and 0.68 ± 0.20 mmol/kg per day) (p = 0.015 and p = 0.132, respectively). Urinary citrate was positively correlated with urinary potassium (r = 0.50, p = 0.002) and urinary magnesium (r = 0.49, p = 0.001). Dietary analysis revealed a lower intake of magnesium and potassium in children with hypocitraturia (28.97% ± 12.25% and 15.42% ± 7.25% recommended dietary index) than in normocitraturic cases (51.06% ± 17.51% and 45.23% ± 29.49% recommended dietary index) (p = 0.042 and p = 0.056, respectively).

The majority of children had an identifiable metabolic risk factor for urolithiasis, with hypocitraturia being the most common. This shift in metabolic trend may be a significant contributor to the increasing incidence in pediatric urolithiasis. Hypocitraturia appears to be dietary in origin, correlated with a low consumption of potassium and magnesium.