Urinary calcium excretion was assessed in 83 consecutive children with gross or microscopic hematuria in whom the presence of proteinuria or urinary-tract infection had been excluded. Twenty-three children had hypercalciuria. Clinical features that were more commonly associated with hypercalciuria included gross hematuria and a family history of urolithiasis. No clinical or pathological basis for the hematuria was determined in 22 of the 23 children with hypercalciuria or in 38 of the 60 children with normal calcium excretion. Urolithiasis developed in two children with hypercalciuria during the period of study. Oral calcium-loading tests were performed in all 23 children with hypercalciuria. Absorptive hypercalciuria was demonstrated in 10 children, whereas 13 had renal (fasting) hypercalciuria. Hematuria resolved during anticalciuric therapy in 20 of the 23 patients with hypercalciuria. We conclude that determination of urinary calcium excretion is warranted in the routine evaluation of children with hematuria.

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Prompted by a large population of children with renal stones seen in 20 of our country's teaching hospitals over the past 10 years, this study of urinary mineral excretion in normal children was performed. Fasting urine from 1,072 normal Taiwanese school children and 24-h urine collections from 125 children separated into three age groups were analysed for calcium (Ca), phosphate, magnesium (Mg), uric acid, sodium (Na) and creatinine (Cr). Fasting Ca/Cr ratios were not different between the sexes. Ca/Cr ratios were higher in the 17- to 18-year age group as were 24-h urinary Ca excretions. Urinary Mg/Cr ratios were higher in girls than boys and 24-h urinary Mg excretion was highest in the younger age groups. Urinary Mg excretion in Taiwanese children is 54%-86% lower than previously reported in Caucasian children. Both uric acid/Cr ratios and 24-h urinary uric acid excretion were highest in the youngest children. Urinary Na/Cr ratios and 24-h urinary Na excretion were higher in the two younger age groups. There was no correlation between 24-h urinary Ca and Na excretion.