Purpose: The role of hypercalciuria for the evaluation of unexplained asymptomatic gross and microscopic hematuria in children remains unclear, as evidenced by conflicting reports in the literature. We study the function of hypercalciuria in these patients, and determine whether routine evaluation of urine for hypercalciuria and treatment with thiazide diuretics, based on the results of a urinary calcium-to-creatinine ratio, is necessary. We also wanted to compare the yield of a urinary calcium-to-creatinine ratio in patients with gross and microscopic hematuria subgroups. Materials and Methods: Between 1991 and 1998 we treated 96 patients with microscopic hematuria (group 1) and 46 with gross hematuria (group 2). All patients had isolated unexplained hematuria. Patients with organic and anatomical causes, including urinary tract infection and other urinary symptoms, were excluded from the study. Nephrological urine and serum analyses in patients with hematuria were otherwise normal, as were all imaging studies. Group 1 included 50 males and 46 females, with a mean age of 7.6 years (range 1 to 14), and a spot urinary calcium-to-creatinine ratio was done in 79. Group 2 included 35 males and 11 females, with a mean age of 8.5 years (range 8 months to 14 years), and a spot urinary calcium-to-creatinine ratio was done in 43. A ratio of 0.2 or greater was considered hypercalciuria. The season of presentation was noted to determine any pattern. Results: There were no seasonal variations regarding presentation. Followup of 34 patients in group 1 and 15 group 2, with a mean followup of 10.6 months (range 1 month to 8 years), was available. A total of 28 (82.3%) patients in group 1 and 15 (71.4%) group 2 had complete resolution of hematuria. However, there were 6 patients in both groups who had persistent hematuria but remained totally asymptomatic. Hydrochlorothiazide was used in only 2 patients in group 1 and 1 group 2 due to intractable hematuria on expectant management, a markedly increased urinary calcium-to-creatinine ratio and positive family history of urolithiasis. Conclusions: Although we cannot establish a direct cause and effect relationship, hypercalciuria is detected in a substantial number of cases of unexplained gross and microscopic hematuria. However, based on our study we do not recommend treatment with thiazide diuretics in all patients diagnosed with hypercalciuria, as hematuria resolved in a majority with observation or expectant treatment and minor dietary modification. We reserve treatment with thiazide diuretics only for those patients with intractable hematuria, a markedly increased urine calcium-to-creatinine ratio and family history of urolithiasis.
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