Urinary Saturations in Children with or without Renal Lithiasis

In lithogenesis, for a stone to form it is necessary that the urine is supersaturated with respect to the salt that will constitute the future stone. The objective was to analyze the urinary saturations of Calcium Oxalate (CaOxa), brushite (calcium phosphate), struvite (ammonium-magnesium phosphate) and uric acid (UA) in children with and without lithiasis. Correlate them with the different parameters involved in the lithiasic process. And compare saturations in children with or without overweight.

We examined 108 healthy children and 53 patients diagnosed with lithiasis. In 24-h urine, the different biochemical parameters involved in lithiasis and the saturation levels of CaOxa, brushite, struvite and UA.

We studied 108 healthy children with a mean age of 9.5 ± 3.9 years. Renal lithiasis was diagnosed in 53 patients with an average age of 10.5 ± 5.8 years. Children with lithiasis had higher saturation values of CaOxa (4.86 ± 2.71 vs. 3.15 ± 1.99, p < 0.01) and brushite (1.58 ± 1.23 vs. 0.86 ± 0.81, p < 0.001) compared to non-lithiasic children. UA saturation was higher in children with body mass index greater than 22 (5.25 ± 3.52 vs. 3.84 ± 3.5, p < 0.04). Finally, urinary pH, ammonium concentration and uricosuria influenced UA saturation. that the urinary pH regression coefficient in the uric acid saturation regression analysis was -4.5.

The mean values of calcium oxalate and brushite saturations were higher in children with lithiasis. Uric acid saturation was elevated in overweight children. Finally, urinary pH greatly influenced uric acid saturation.