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

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.

Nefrocalcinosis en recién nacidos prematuros / Nephrocalcinosis in preterm infants

El objetivo de este estudio es conocer la incidencia de nefrocalcinosis en recién nacidos de pretérmino y determinar la utilidad de la relación calciuria/creatininuria como predictor diagnóstico. Un total de 124 recién nacidos con edad gestacional igual o menor a 32 semanas fueron agrupados en dos categorías. Un grupo de estudio de 53 pacientes con factores de riesgo conocidos para el desarrollo de nefrocalcinosis (oxigenoterapia, uso de furosemida y nutrición parenteral prolongadas) y un grupo control de 71 pacientes sin factores de riesgo. Ambos fueron estudiados por índice calciuria/creatininuria (muestras aisladas de orina los días 15, 21 y 30 de vida). Se definió hipercalciuria como un valor igual o mayor a 0,5 de índice calciuria/creatininuria presente al menos en dos muestras aisladas de orina. Se realizó estudio ecográfico entre los dos y tres meses de vida. El 15,3 por ciento de los pacintes presentó nefrocalcinosis. El grupo con factores de riesgo presenta 35,8 por ciento de nefrocalcinosis y los valores de calciuria/creatininuria fueron 0,87, 0,96 y 1,04. En el grupo control de valores de calciuria/creatininuria fueron 0,37, 0,30 y 0,29 no presentando casos de nefrocalcinosis. La diferencia entre ambos grupos es estadísticamente significativa (p<0,01). La presencia de hipercalciuria se relaciona con el diagnóstico de nefrocalcinosis, presentando valor predictivo positivo de 38 por ciento y valor predictivo negativo de 100 por ciento. La incidencia de nefrocalcinosis es comparable con series clínicas publicadas. Parece adecuado el estudio de pacientes con factores de riesgo por medio de calciuria/creatininuria realizando seguimiento ecográfico de pacientes con hipercalciuria