Nephrocalcinosis in very low birth weight infants: a single center experience

Abstract

Objectives: To determine the incidence and risk factors of nephrocalcinosis in very low birth weight infants.

Material and method: Medical records of inborn infants with gestational age less than 32 weeks or birth weight less than 1,250 grams were collected and analyzed. All infants were born at King Chulalongkorn Memorial Hospital in the year 2003. At least one renal ultrasonographic scan was performed on every infant as a routine screening before discharge. Data on family history of renal stone, gestational age, birthweight, infant's illness,fluid intake during the first 6 weeks of life, duration of respiratory support, medications, serum calcium, phosphate and alkaline phosphatase level, duration of parenteral nutrition, length of hospitalization, ultrasonographic findings and related renal morbidity were collected and compared between the groups of infants with and without nephrocalcinosis.

Results: Thirty six infants were included in the present study. Fourteen had abnormal ultrasound scans compatible with nephrocalcinosis giving an overall incidence of 38.9%. Factors associated with nephrocalcinosis included severity of respiratory illness, PDA, oxygen dependency, furosemide therapy, and fluid restriction. Urinary tract infection was the renal morbidity found in 3 infants (21.4%). Nephrocalcinosis was resolved in one out of 7 infants who had repeated renal ultrasound scan at about 2 months after the first scan.

Conclusion: Very low birth weight, preterm infants have a risk of developing nephrocalcinosis especially those with severe respiratory illness and prolonged use of furosemide. Infants at risk should be screened with renal ultrasonography prior to discharge from the hospital.