Comparison of Blood and Urine Renal Indices Between Hypercalciuric and Non-hypercalciuric Hematuria Patients

ABSTRACT

PURPOSE: The purpose of this study was to investigate whether hypercalciuria patients with hematuria show different renal indices compared to non-hypercalciuria patients with hematuria. METHODS: We retrospectively reviewed the medical records of patients with gross or microscopic hematuria whose blood chemistry and 24 hour urine chemistry were examined. After excluding the patients with more than 4 mg/m2/day proteinuria or the patients with urinary calcium excretion between 3 and 4 mg/kg/day, we divided the patients into two groups a hypercalciuria group whose calcium excretion was more than 4 mg/kg/day(n=30) and a non- hypercalciuria group whose calcium excretion was less than 3 mg/kg/day(n=41). The urinary excretion, clearance, and fractional excretion(FE) of Na, K, Cl, Ca, P, urea, and creatinine were calculated and compared between the two groups. RESULTS: The hypercalciuria group had more calcium excretion(6.1+/-2.9 vs 1.5+/-0.9 mg/kg/day), more urea excretion(341+/-102 vs 233+/-123 mg/kg/day), greater glomerular filtration rate(GFR) (93.7+/-31.1 vs 79.5+/-32.0 mL/min) but lower FENa(1.0+/-0.4% vs 1.3+/-0.6%) than the nonhypercalciuria group, although the urinary sodium excretion was similar between the two groups. CONCLUSION: The greater urea excretion and GFR in hypercalciuric patients suggest that they might be on a higher protein diet than the non-hypercalciuria group. The increased glomerular filtration of sodium and calcium induced by the higher GFR in hypercalciuria would have increased their delivery to the distal tubule, where sodium is effectively reabsorbed but calcium is not, which is suggested by the lower FENa but higher FECa in hyercalciuria. It is recommended that the diet of hematuria patients be reviewed in detail at initial presentation and during treatment.