Abstract 1311 Poster Session II, Sunday, 5/2 (poster 197)

Introduction: The incidence of nephrocalcinosis (NC) in preterm neonates varies widely from 17-64%. The causes are not yet elucidated. The aim of this study was to investigate the incidence and causes of NC in preterm neonates.

Methods: In a prospective study conducted from 1-5-1996 to 1-5-1997 86 preterm neonates with a gestational age 32 weeks were investigated. Patient characteristics and intake of calcium, phosphate, protein, vitamin D, medication etc were noted. 4 weeks postnatally and at term an ultrasound of the kidneys was performed and excretion of calcium, oxalate and citrate was measured in 4 h urine samples. Patients with NC at term were studied at the age of 1 year.

Results: At 4 weeks postnatally NC was positive in 21(33%), dubious in 13(20%) and negative in 30(47%) of the patients. At term NC was positive in 34(44%), dubious in 9(11%) and negative in 35(45%) of the patients. Calcium and phosphate intake in the first 4 weeks of life was significantly higher in prematures with NC compared to prematures without NC. Serum calcium at 4 weeks postnatally was significantly higher in prematures with NC. In line with our earlier reported data Ucalcium/creatinine- at 4 weeks and Ucalcium/citrate-ratios at term were significantly higher in prematures with NC (p<0.05). There was no significant difference in gestational age, days of parenteral feeding, vitamin D intake, and the use of furosemide and corticosteroids. At the age of 1 year 9 of 27 studied patients still had NC.

Conclusion: NC can be found in 33% of preterm neonates 4 weeks postnatally and in 44% at term. High intake of calcium and phosphate plays an important role in the pathogenesis. In prematures with NC higher Ucalcium/creatinine and Ucalcium/citrate are found. More children have to be included and followed to further evaluate causes and prognosis of NC. funded by The Dutch Kidney Foundation