Glomerular filtration rate in the preterm infant: the relation to gestational and postnatal age

Abstract

In 41 preterm neonates with a gestational age (GA) varying from 27 to 36 weeks, glomerular filtration rate (GFR) was measured by means of the continuous inulin infusion technique. The reliability of the technique was confirmed. During postnatal development GFR was found to increase in two ways: firstly, an increase with advancing gestational age, associated with the increase in body weight (BW) [GFR (ml/min) = 0.15 X GA-3.20, r = 0.48, P = 0.0048]; secondly, a postnatal increase, being independent from increment in BW. An increase in GFR (ml/min.kg) from 0.88 +/- 0.23 to 1.18 +/- 0.28 was observed between day 4 and day 11 postnatally (P less than 0.008). This latter increase is probably associated with changes in renal haemodynamics. No significant influence of artificial ventilation on GFR could be demonstrated in preterm neonates.