Idiopathic hypercalciuria of childhood: response to oral calcium loading in children with and without urolithiasis.

Fifteen children with episodes of painless hematuria without calculi and 8 others with calcareous urolithiasis were examined for hypercalciuria. All patients were normocalcemic and excreted excessive amounts of urinary calcium (greater than 4 mg. per kg. per day). A familial history for renal calculi was noted in 8 children with hematuria and in 5 with urolithiasis. Children with hematuria excreted greater amounts of calcium and presented at an earlier age compared to patients with renal calculi. After 7 days of a low calcium diet an oral calcium loading test was performed in children from both groups. Urinary calcium excretion and parathyroid activity were not different in the 2 clinical groups while fasting or after an oral calcium load. Absorptive and renal subtypes were found in patients with hematuria and urolithiasis. Treatment used to prevent the recurrence of calculi also was highly effective in resolving hematuria. Despite differences in age and clinical presentation, these children appeared metabolically similar and responded favorably to therapeutic regimens that reduce urinary calcium excretion.