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Urinary saturation and nephrocalcinosis in preterm infants: effect of parenteral nutrition
Insights
Total parenteral nutrition (TPN) in preterm infants increases urinary calcium oxalate saturation, raising the risk of kidney stones. Breastmilk feeding with glucose-sodium chloride infusion is associated with lower saturation levels and better urinary profiles.
Area of Science:
- Pediatric Nephrology
- Neonatal Nutrition
- Biochemistry
Background:
- Preterm infants are susceptible to urinary tract issues.
- Nutritional support, including total parenteral nutrition (TPN) and breastmilk feeding, can influence urinary composition.
Purpose of the Study:
- To compare urinary lithogenic and inhibitory factors in preterm infants receiving TPN versus breastmilk with glucose-sodium chloride infusion.
- To assess the impact of different feeding methods on urinary calcium oxalate saturation and the risk of nephrocalcinosis.
Main Methods:
- 27 preterm infants were studied: 16 on TPN and 11 on breastmilk/infusion.
- 24-hour urine collections were performed at specific time points (days 2, 3, and 4-10).
- Urinary calcium oxalate saturation was calculated using EQUIL 2; renal ultrasonography was conducted periodically.
Main Results:
- Infants on TPN showed significantly higher calcium/creatinine and oxalate/creatinine ratios, and a higher calcium/citrate ratio compared to the breastmilk group.
- Urinary calcium oxalate saturation increased with TPN and decreased with breastmilk/infusion.
- Nephrocalcinosis occurred in two infants receiving TPN.
Conclusions:
- TPN in preterm infants leads to increased urinary calcium oxalate saturation due to higher calcium excretion and altered oxalate and citrate levels.
- Breastmilk feeding with glucose-sodium chloride infusion appears to offer a protective effect against urinary stone formation in preterm infants.
- Nutritional strategies significantly impact urinary risk factors for nephrolithiasis in preterm neonates.
Abstract:
Urinary lithogenic and inhibitory factors were studied in 27 preterm infants; 16 had total parenteral nutrition (TPN) and 11 had breastmilk with an additional glucose-sodium chloride infusion. Urines were collected for 24 hours on day 2 (period A), day 3 (B), and once between days 4 and 10 (C). Urinary calcium oxalate saturation was calculated by the computer program EQUIL 2. Renal ultrasonography was performed every second week until discharge. The calcium/creatinine ratio increased in infants on TPN (A 0.91; C 1.68 mol/mol) and was significantly higher at period C than that in infants on breastmilk/infusion (A 0.52; C 0.36). The oxalate/creatinine ratio was persistently higher with TPN (203 mmol/mol) than with breastmilk/infusion (98; 137). The citrate/creatinine remained constant with TPN (0.44 mol/mol), whereas it increased significantly with breastmilk/infusion (0.26; 0.49). Calcium/citrate rose considerably with TPN, but decreased with breastmilk/infusion to a significantly lower level than with TPN. The urinary calcium oxalate saturation increased with TPN (2.4; 4.5) and decreased with breastmilk/infusion (2.1; 1.5) to a significantly lower value than with TPN. Nephrocalcinosis developed in two infants on TPN. Mean daily calcium intake was similar in both groups, whereas protein, sodium, and phosphorus intake were significantly higher on TPN. It is concluded that the increase in urinary calcium oxalate saturation observed with TPN is due to the combined effect of an increased urinary calcium excretion and higher urinary oxalate/creatinine and calcium/citrate ratios. The changes observed are likely to be caused by TPN itself, which differs in several respects from breastmilk feeding.