A study of the etiology of idiopathic calcium urolithiasis in children: hypocitruria is the most important risk factor.

Purpose: To determine the association of metabolic risk factors with pediatric calcium urolithiasis we compared metabolic evaluation data on children with idiopathic calcium stones and those on healthy children.

Materials And Methods: Metabolic evaluation was done in 78 calcium stone formers 1 to 15 years old (mean age 7.2) who were free of urinary tract infection, anatomical abnormalities, and metabolic, endocrinological and intestinal disorders, and in 24 healthy children. Evaluation included serum biochemistry, and measurement of daily excretion of urinary calcium, oxalate, urate, phosphorus, citrate and magnesium.

Results: Demographic characteristics, serum parameters, and daily excretion of calcium, urate, phosphorus and magnesium did not differ statistically in the 2 groups. However, urinary oxalate was significantly higher and urinary citrate was significantly lower in stone formers than in controls (p = 0.002 and 0.028, respectively). Hypocitruria and hyperoxaluria were 4.3 and 3-fold more common in stone formers than in controls, respectively. Multivariate analysis using logistic regression showed that hypocitruria was the only significant risk factor for idiopathic calcium stones (p = 0.008).

Conclusions: Hypocitruria was the most important risk factor in our patients. Hyperoxaluria was also common and accompanied hypocitruria in many stone formers. In contrast to many previous reports, we failed to show that hypercalciuria is an important metabolic defect for idiopathic calcium stones, possibly because our study evaluated a different population.