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Renal function in very low birth weight infants: normal maturity reached during early childhood
1Department of Pediatrics, Karolinska Institute, St. Göran's Children's and Karolinska Hospital, Stockholm, Sweden.
Insights
Renal function in very low birth weight infants matures by age 8, but not by 9 months corrected age. Glomerular filtration rate is lower in preterm infants at 9 months corrected age compared to term infants.
Area of Science:
- Neonatal physiology
- Pediatric nephrology
- Developmental biology
Background:
- Renal function development is often delayed in preterm infants.
- Understanding the long-term renal maturation trajectory in these infants is crucial.
Purpose of the Study:
- To investigate the pattern of renal function maturation in very low birth weight infants during infancy and childhood.
- To compare renal function in preterm infants at corrected ages of 9 months and 8 years with appropriate controls.
Main Methods:
- Longitudinal re-evaluation of renal function in 22 very low birth weight infants.
- Assessment included glomerular filtration rate, effective renal plasma flow, filtration fraction, albumin excretion, maximal concentrating ability, and kidney size via ultrasonography.
- Comparison with term infants and healthy control subjects at relevant ages.
Main Results:
- Glomerular filtration rate was significantly lower at 9 months corrected age in preterm infants compared to term infants (82 +/- 23 vs. 125 +/- 18 ml/min per 1.73 m2).
- By 8 years of age, glomerular filtration rate in the formerly preterm infants did not differ from healthy controls.
- Other parameters like effective renal plasma flow, filtration fraction, albumin excretion, concentrating ability, and kidney size were normal at 8 years of age.
Conclusions:
- Renal function, initially reduced in very low birth weight infants, demonstrates catch-up maturation.
- Normal renal maturity is achieved by 8 years of age, but not by 9 months corrected age in this cohort.
- These findings highlight the prolonged but ultimately successful renal development in very low birth weight infants.
Abstract:
Development of glomerular and tubular renal function is delayed in preterm infants. To study the pattern of maturation during infancy and childhood, we re-evaluated renal function in 22 very low birth weight infants--in 14 of the infants at 18 months postconceptional age (9 months corrected age) and in the remaining 8 infants at 8 years of age. The glomerular filtration rate remained lower at 9 months corrected age than in term infants of the same postconceptional age: 82 +/- 23 versus 125 +/- 18 ml/min per 1.73 m2 (p < 0.001). At 8 years of age the glomerular filtration rate did not differ from that of healthy control subjects. Effective renal plasma flow, filtration fraction, albumin excretion, maximal concentrating ability, and kidney size determined by ultrasonography were all normal at 8 years of age. We conclude that renal function, which is markedly reduced during the neonatal period in very low birth weight infants, reaches normal maturity by 8 years of age but not by 9 months corrected age.