Physicochemical factors of the urine of children with hypercalciuria

Hypercalciuria is a common lithogenic risk factor. The aim of this study was, first, to study the characteristics of urine biochemical factors of children with hypercalciuria (HC) and compare them with those of children without hypercalciuria. Second, to analyze the differences between children with HC and lithiasis (HCL) and children with HC and no lithiasis (HCNL).

The sample was composed by 111 cases with HC, divided into 2 groups: HCNL group, consisting of 93 cases with no personal history of kidney stones, and HCL group, 18 cases with personal history of kidney stones. As a cohort control group, 113 healthy children were used. Creatinine, urea, sodium, potassium, chlorine, uric acid, calcium, phosphorus, magnesium and osmolality: blood and 24-hour urine following parameters were determined. Oxalate and citrate were determined in urine.

The mean values of natriuresis, uricosuria, phosphaturia, magnesuria, citraturia, calcium oxalate and calcium phosphate saturation were higher in HCNL than in control group. The HCL group had phosphaturia, calcium oxalate and calcium phosphate saturations more elevated compared with the control group. There were no significant differences in urinary excretion of various parameters when the groups HCL and HCNL were compared.

Our results show that children with hypercalciuria without lithiasis associated show an increase in natriuresis, phosphaturia, uricosuria, magnesuria and citraturia. We found no differences between these urinary abnormalities when compared hypercalciuric children without lithiasis with those with hypercalciuria and urolithiasis.