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Urinary oxalate excretion by very low birth weight infants receiving parenteral nutrition
1Department of Pediatrics and Medicine, Baystate Medical Center, Springfield, Massachusetts 01199.
Insights
Total parenteral nutrition (TPN) in very low birth weight (VLBW) infants is linked to higher urinary oxalate levels. This may contribute to kidney calcifications, a concern in VLBW infants receiving TPN.
Area of Science:
- Neonatal Medicine
- Pediatric Nephrology
- Biochemistry
Background:
- Renal calcifications are observed in very low birth weight (VLBW) infants, with diuretic-induced hypercalciuria implicated in their development.
- Hyperoxaluria is a known risk factor for renal stone formation in pediatric and adult populations.
- Parenteral nutrition (PN) solutions contain oxalate precursors, namely ascorbate and glycine, raising questions about their impact on oxalate excretion in infants.
Purpose of the Study:
- To investigate the association between total parenteral nutrition (TPN) administration and oxalate excretion in VLBW infants.
- To determine if varying protein levels in TPN influence urinary oxalate concentrations in this vulnerable population.
Main Methods:
- Comparison of urinary oxalate concentration and oxalate to creatinine ratio in VLBW infants receiving different nutritional regimens.
- Inclusion of VLBW infants receiving TPN (0.5 g/kg/day and 1.5 g/kg/day protein) and those receiving glucose/electrolyte solutions.
Main Results:
- VLBW infants receiving TPN (0.5 g/kg/day protein) showed increased urinary oxalate concentration and oxalate to creatinine ratio compared to controls.
- A further elevation in urinary oxalate levels was observed in VLBW infants receiving higher protein TPN (1.5 g/kg/day).
Conclusions:
- Elevated urinary oxalate concentrations can occur in VLBW infants receiving TPN.
- Increased oxalate excretion associated with TPN may be a contributing factor to nephrocalcinosis in VLBW infants.
Abstract:
Renal calcifications have been described in very low birth weight (VLBW) infants, and diuretic drug-associated hypercalciuria is believed to play a role in the pathogenesis of this lesion. Hyperoxaluria is an important cause of renal stone formation in children and adults. Because parenteral nutrition solutions contain the oxalate precursors ascorbate and glycine, the relationship between total parenteral nutrition administration and oxalate excretion in VLBW infants was examined. Administration of approximately 0.5 g of total parenteral nutrition protein per kilogram per day to VLBW infants was associated with an increased urinary oxalate concentration and an increased urinary oxalate to creatinine ratio, when compared with VLBW infants receiving a glucose and electrolyte solution. A further increase in urinary oxalate concentration and oxalate to creatinine ratio was noted when total parenteral nutrition protein was increased to approximately 1.5 g of protein per kilogram per day. In VLBW infants who receive total parenteral nutrition, elevated urinary oxalate concentrations may develop and may be a factor in the pathogenesis of nephrocalcinosis in these infants.