Are low birth weight neonates at risk for suboptimal renal growth and function during infancy?

A Iyengar,N Sinha,S Nesargi,V A Luyckx,S Selvam,A George

doi:10.1186/s12882-016-0314-7

A Iyengar, N Sinha + Show 4 more

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https://doi.org/10.1186/s12882-016-0314-7

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Abstract

BackgroundTo assess the renal growth and function of neonates during infancy in relation to birth weight and gestational age.MethodsA longitudinal study was conducted at a tertiary hospital in South India from June 2010 to August 2014. Low birth weight neonates (LBW) were further sub-classified based on gestational age and compared with normal birth weight (NBW) full term neonates at birth, 6 months and 18-24months of age. The renal volume was measured by ultrasound and renal function by Cystatin C- derived glomerular filtration rate (CysGFR) at the three time points during the dynamic phase of renal maturation in infancy.ResultsWe recruited 100 LBW and 66 NBW term neonates. Thirty five percent of the LBW neonates were SGA. Among the AGA neonates, 39 % were LBW neonates. The mean height and weight of the LBW neonates were significantly lower compared to NBW neonates throughout infancy. The increment in kidney volume was in accordance with the change in body size, being lower in LBW compared to NBW infants. The combined kidney volume was significantly lower in LBW and SGA neonates across all three time points (p < 0.001). CysGFR in the LBW and SGA infants, despite having low kidney volumes, were comparable to the GFRs of NBW and AGA neonates at the end of infancy.ConclusionThis study highlights the fact that both birth weight and gestational age influence kidney growth and function in infancy. At the end of infancy, despite a significant difference in kidney volumes and age at last follow up, the glomerular filtration rate was comparable between LBW and NBW infants. Though not statistically significant, there was a trend towards higher urine microalbumin in LBW compared to NBW in infancy.Electronic supplementary materialThe online version of this article (doi:10.1186/s12882-016-0314-7) contains supplementary material, which is available to authorized users.

Highlights

To assess the renal growth and function of neonates during infancy in relation to birth weight and gestational age
The independent t-test was used to compare the continuous variables such as body weight, body surface area, serum cystatin C, CysGFR and combined renal volumes between Low birth weight neonates (LBW) and normal birth weight (NBW) neonates at birth
Mixed model analysis was performed to compare the mean kidney volume and function overtime separately between LBW and NBW neonates, considering study group (LBW/NBW and small for gestational age (SGA)/appropriate for gestational age (AGA)) and time as factors adjusting for sex, BSA and kidney volume

Summary

Introduction

To assess the renal growth and function of neonates during infancy in relation to birth weight and gestational age. Studies on neonates suggest that Indian babies are born smaller but are relatively fatter compared to Caucasian babies and are referred to as the” thin fat Indian baby” [6]. This thin fat phenotype persists in childhood and is a forerunner of diabetes and metabolic. LBW babies have a lower nephron mass [12]. Risk factors for low nephron mass and /or kidney dysfunction are low birth

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