Metabolic risk factors in children with asymptomatic hematuria.

Background: Idiopathic or benign hematuria is diagnosed in children after all other possible causes have been ruled out and test results for renal or urologic pathologies are negative.

Methods: To identify possible urinary risk factors for hematuria in children, we retrospectively evaluated clinical onset, family history, and metabolic risk factors of 60 children with idiopathic hematuria but without renal stones or other pathologic conditions that could explain the hematuria. All patients followed the same ambulatory protocol at that used to evaluate kidney stone-formers.

Results: Seven patients had microhematuria, three patients each had microhematuria and gross hematuria, and the remaining 50 patients had gross hematuria onset. A family history of stone disease was found in 63 % of the children. At least one urinary metabolic abnormality was present in 49 patients, while 11 patients had no metabolic abnormality. The most common urinary risk factor was idiopathic hypercalciuria (single or associated), which was found in 43.5 % of patients, followed by hypocitraturia (single or associated), present in 31.7 %. Unduly acidic urine pH as a single abnormality was found in 10 % of this pediatric patient population. We also found hyperoxaluria and, less frequently, hypomagnesuria, and hyperuricosuria.

Conclusions: Asymptomatic idiopathic hematuria in pediatric patients may often be associated to different urinary biochemical abnormalities, similar to what is observed in pediatric kidney stone-formers.