Risk Factors of Nephrocalcinosis in Very Low Birth Weight(VLBW) Infants

Shim, Gyu Hong; Lee, Jin A; Shin, Yun Jung; Kim, Ee Kyung; Park, June Dong; Kim, Beyong Il; Choi, Jung Hwan

Abstract

PURPOSE
Nephrocalcinosis in very low birth weight(VLBW) infants were known to be caused by a longer duration of furosemide use. However, etiologies, pathogenesis and risk factors remain unclear. Therefore, we examined the incidence and risk factors of nephrocalcinosis in VLBW infants retrospectively.
METHODS
Inborn babies of birth weights less than 1,500 gm were examined retrospectively. Data were reviewed on gestational age, birth weight, sex, 5-min Apgar score, oliguria on the first day, respiratory support, surfactant use, duration of nephrotoxic drug use(furosemide, gentamicin, amikin, vancomycin and amphotericin-B) and duration of total parenteral nutrition(TPN) use. Presence of bronchopulmonary dysplasia(BPD), bacterial sepsis, fungal sepsis, osteopenia and necrotizing enterocolitis(NEC) were also reviewed. Serum calcium, phosphorus, total protein, albumin, blood urea nitrogen (BUN) and creatinine at three to five weeks of age and at discharge were reviewed.
RESULTS
A t-otal 141 infants were reviewed. 9.2%(13/141) of VLBW infants developed nephrocalcinosis. By univariate analysis, gestational age, birth weight, 5-min Apgar scores, duration of ventilation, duration of oxygen use, postnatal dexamethasone, phototherapy, nephrotoxic drugs(furosemide, amikin, vancomycin, and amphotericin) and TPN were significantly associated with nephrocalcinosis. Low phosphorus level at three to five weeks of age and high BUN levels at discharge were significantly associated with nephrocalcinosis. Presence of RDS, BPD, bacterial sepsis, fungal sepsis and NEC were also significantly associated with nephrocalcinosis. Multivariate analysis showed that the strongest predictors of nephrocalcinosis were duration of furosemide use and birth weight.
CONCLUSION
Longer duration of furosemide use and lower birth weight are considered to be independent risk factors. Further more prospective and longterm follow up studies are needed.