THE IDENTIFICATION OF HYPEROXALURIA IN VERY-LOW-BIRTH-WEIGHT INFANTS - WHICH URINE SAMPLING METHOD

The present study was performed to determine the best method of urine collection for measurement of oxalate excretion in very low-birthweigh t (VLBW) infants and to verify the utility of the oxalate/creatinine r atio in VLBW infants, This has not been investigated in this group wit h developing renal function, In a prospective study of 30 VLBW infants , we compared oxalate excretion in urine collected over 24 h and in a spot urine sample. The urinary oxalate concentration was measured by t he oxalate oxidase method. The correlation coefficient between the amo unt of oxalate per kilogram body weight excreted daily and the oxalate /creatinine ratio in spot urine sample was 0.80 (P<0.0001) and with th e oxalate/creatinine ratio in a 24-h urine collection 0.82 (P<0.0001). The two highest levels of oxalate excretion (>100 mu mol/kg per day) were detected with both oxalate/creatinine ratios (>1 mmol/mmol). No c ircadian rhythm of oxalate excretion was found. The measurement of the oxalate/creatinine ratio in spot urine samples is suitable for screen ing VLBW infants for hyperoxaluria.