Progression of renal function in preterm neonates with gestational age <= 32 weeks

Serum creatinine (SeCr), creatinine clearance (CrCl), and fractional excret ion of sodium (FeNa) were measured in 83 preterm neonates divided into four groups according to gestational age (GA). At birth, there were no differen ces in mean SeCr values in the four groups nor any significant correlation between initial values and GA. In all groups there was an initial SeCr incr ease; an inverse correlation between SeCr and GA was observed from the 3rd day of life to the 5th week (p<0.001). CrCl showed a positive correlation t o GA from the first week onwards (p<0.001); in each group CrCl values corre lated positively to days of life (p=0.0001), Rate of CrCl increase correlat ed positively to GA (p=0.0005). FeNa showed an inverse correlation to GA fr om the first week (p<0.001). In each group, the FeNa value correlated negat ively to postnatal age (p<0.001) and the velocity of decrease was directly cor related to GA (p=0.0358). Our findings indicate that glomerular functio n shows a progression directly correlated to GA and postnatal age, while tu bular function correlates inversely to the same parameters. The values repo rted could be useful for following renal function in very low birth weight infants.