COMPARISON OF METHODS FOR DETERMINATION OF GFR IN PRETERM NEONATES

Abstract

A simplified method for accurate determination of GFR would be useful in the management of critically ill, premature neonates. Serum creatinine (Sc) has been used to estimate GFR in children and adults but its validity in preterm infants has yet to be established. The purpose of this study was to compare GFR as estimated from Sc to that determined by three accepted clearance methods: UV/P creatinine clearance (Cc), UV/P inulin (In-a), and inulin constant infusion method (In-b). Eleven neonates with RDS (BW 2.24 ± .5 kg, GA 33 ± 1.7 wks, length 45.9 ± 4.2 cm) were studied longitudinally during the first 5 days of life. Timed urine collections (233 ± 48 min) for Cc were performed every eight hours in 8 patients. Once each day, simultaneous with Cc, In-a was performed in 5 infants, and In-b was performed in 7 infants. GFR was estimated from Sc and length (Sc-L) using the formula: GFR (ml/min/1.73 m2) = .4 X length (cm)/Sc (mg/dl) (Feld et al, Ped. Res. 17:1567, 1983). Comparison of methods is shown below.