The effect of intrauterine growth retardation on renal function in the first two months of life

Background. Children born with growth retardation (GR) have a smaller nephron number and are at increased risk for the development of renal disease and hypertension in adult life. Data on the immediate post-natal development of renal function in neonates born with GR are limited and data on the effects of aminoglycosides (AGs) on renal function in these infants are lacking. Methods. This was a prospective study of 81 preterm neonates with a mean gestational age of 32.5 weeks, 40 born with GR (small for gestational age, SGA) and 41 without GR (appropriate for gestational age, AGA). The infants were classified into 4 groups. Groups A (n = 21) and B (n = 20) consisted of AGA and SGA neonates, respectively, who received AGs, and groups C (n = 20) and D (n = 20) of AGA and SGA neonates, respectively, who did not receive AG treatment. Indices of renal function were: serum creatinine (SeCr), the fractional excretion of sodium (FENa), potassium (FEK), phosphorus (FEP), magnesium and uric acid (FEUA), the urinary calcium/creatinine ratio and the transtubular potassium gradient (TTKG). Results. No differences were observed in the parameters examined between SGA and AGA neonates who did not receive AGs. Conversely, SGA infants who received AGs after birth (group B) exhibited higher values of SeCr 2 months later. Specifically, their mean +/- SD value of SeCr (mu mol/l) was 42 +/- 05 compared with 33 +/- 08 in group D, 35 +/- 04 in group A and 33 +/- 04 in group C (P < 0.01). These infants also had significantly higher values of TTKG than SGA infants without AG treatment (22 +/- 9 vs 13 +/- 3 in group D) and FEUA (60 +/- 23 vs 35 +/- 14 in group D). Their FENa and FEP were also inappropriately high despite having lower serum levels of Na and P. Conclusion. Preterm SGA infants who had no need of AG treatment after birth have similar renal functional maturation than AGA preterm infants at 2 months of life, but preterm SGA infants who received AGs had indications of impaired glomerular and tubular function at this age.