Should We Screen Preterm Infants for Nephrocalcinosis? An Evidence-based Decision

Shahirose S Premji; Majeeda Kamaluddeen

Disclosures

Pediatr Health. 2010;4(1):24-35. 

In This Article

Prevention & Treatment

Based on experience with children and adults, citrate therapy has been studied as a preventative therapy for nephrocalcinosis in premature infants.[33] Citrate not only disrupts the crystallization process of calcium-oxalate crystals, it also forms a more soluble complex with calcium.[33,34] A randomized, controlled trial in preterm infants with a gestational age less than 32 weeks (n = 38) receiving sodium citrate (0.13 mmol/kg/dose, four-times per day) beginning at day 8 of life until 38 to 42 weeks postconceptual age showed no difference in incidence of nephrocalcinosis. No adverse effects (e.g., diarrhea and vomiting) were noted.[33] Recruitment is currently in progress for another randomized, controlled trial entitled Alkaline Citrate Treatment to Lower the Risk of Nephrocalcinosis in Preterm Infants at the University of Cologne, Germany, by Hoppe. Of note, the normal range for urinary citrate for term babies was determined and no differences in values were reported between healthy full-term infants and term-corrected preterm infants born at less than 32 weeks' gestation.[35]

Extracorporeal shock wave lithotripsy (ESWL) breaks kidney stones into small particles, which are then removed by normal flow of urine from the kidney to the bladder. A review concluded that ESWL is the 'best treatment' and 'first-choice treatment' for removal of kidney stones in the pediatric population regardless of age.[36] In this review, one study[37] was identified that specifically focused on infants born at less than 32 weeks' gestation age and with a birth weight less than 1500 g. Eight infants, of whom seven had a history of bronchopulmonary dysplasia requiring furosemide therapy, were treated at a mean age of 13 months. All patients required general anaesthesia, and none received intravenous sedation. One patient with bilateral renal pelvic stones required two separate sessions with a 4-week interval between sessions of ESWL. All patients were stone-free at 3 months post-treatment and none required retreatment.[37] Shock waves may have an adverse effect (e.g., hematoma and fibrosis) on the growing kidney.[36] No morphological changes were found at 2 weeks follow-up, serum creatinine levels also remained unchanged post-treatment.[37] The efficacy in LBW infants has been attributed to the small body volume that permits transmission of shock waves with minimal loss of energy and the supple and expandable nature of the ureter that permits easier transmission of the smaller particles resulting as a consequence of treatment.[36] A longitudinal pilot study of premature infants not included in the review also concluded, "[ESWL] had excellent result with no residual stone burden"[5] in two patients who developed frank renal stones after persistent nephrocalcinosis.

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