Idiopathic hypercalciuria and hyperuricosuria: family prevalence of nephrolithiasis.

We studied the prevalence of a history of nephrolithiasis in first- and second-degree relatives of 74 children with hypercalciuria (HC), 61 with hyperuricosuria (HU), and 41 with HC plus HU, and in a control population of 261 children with different diseases. Family history of nephrolithiasis was found in 69% of HC, 75% of HU, 78% of HC plus HU, and 22% of control patients. The prevalence was not different among HC, HU, and HC plus HU groups, but was significantly higher in each study group than the control group (P=0.0001). Body mass index >95th percentile was found in only 4.7% of the patients with HC or HC plus HU. Calculi (>3 mm in diameter) were present in 8.9% of the patients with a family history of nephrolithiasis and in 9.4% of those with no family history (P=0.85). Microcalculi (<3 mm in diameter) were found by sonography in 56.6% of the patients with and in 53.3% of those without a family history of nephrolithiasis (P=0.83). Children with HC and/or HU have a strong familial prevalence of nephrolithiasis. Obesity does not seem to affect the association of familial nephrolithiasis and hypercalciuria in children. The presence of nephrolithiasis in families of children with HC and/or HU is not associated with a higher rate of formation of calculi or microcalculi.