Random Urine Ca/Cr Ratio in Healthy Neonates

ABSTRACT

PURPOSE: Recently, in high risk preterm infants, we experienced high incidence of hypercalciuria, nephrolithiasis & nephrocalcinosis. To screen hypercalciuria, we need the normal value of random urine Ca/Cr ratio in healthy neonates according to gestational age, postnatal age, milk and calcium intake. METHODS: Random urine Ca/Cr ratio was checked in 260 healthy full-term infants at the 2-7th day, and in 40 preterm infants at the 3-16th day when they started formula feeding at Ewha Universaity Mok-dong Hospital from March 1995 to October 1995. We calculated calcium amount in formulas and we excluded the neonates who needed extra calcium supplement. RESULTS: There were no significant relationships between random urine Ca/Cr ratio and body weight or gestational age. There were significant logistic positive relationships between random urine Ca/Cr ratio and postnatal age (r=0.47, P<0.05) or calcium intake (r=0.52, P<0.05). The velocity of increase in random urine Ca/Cr ratio in term and preterm infants is not significantly different. The normal values of random urine Ca/Cr ratio in healthy term and preterm infants were 0.026 0.013 (Max. 0.052) at the early neonatal period with low calcium intake, and 0.075 0.0310 (Max. 0.137) at the late neonatal period with adequate calcium intake. CONCLUSION: Random urine Ca/Cr ratio was very low in healthy neonates and increase in a logistic line according to calcium (milk) intake. New normal value of random urine Ca/Cr ratio in neonates according to calcium (milk) intake is suggested to screen hypercalciuria.