Bepaling van de glomerulaire filtratiesnelheid bij kinderen door middel van de inuline single injectiemethode

Background. Renal function can be assessed by determination of the glomerular filtration rate (GFR). The standard method to determine GFR in children is the urinary clearance of inulin during a continuous intravenous infusion. However, this method is complex and invasive. Alternatively, the plasma clearance of inulin can be determined by single injection of inulin. The aim of this study was to validate the single injection method with a limited number of blood samples in pediatric patients. Method. Determination of the inulin plasma clearance by single injection was performed in 48 patients. A single injection of inulin (5000 mg/m²) was administered and blood samples were withdrawn at 0, 10, 20, 30, 45, 60, 90, 120, 150, 180 and 240 minutes after administration. The inulin plasma clearance based on four blood samples (10, 30, 90 and 240 minutes) was compared with the inulin plasma clearance based on all blood samples (reference clearance). Results. In patients with GFR < 75 ml/min/1.73 m² the mean difference between the inulin plasma clearance based on four blood samples and the reference clearance was not statistically significant. For GFR > 75 ml/min/1.73 m² a small bias was observed (mean difference: -5.92 ml/min/ 1.73 m²; 95% confidence interval: -10.2 to -1.68 ml/min/ 1.73 m²). Conclusion. In patients with decreased renal function the inulin plasma clearance determined by the single injection method with four blood samples agreed well with the inulin plasma clearance based on eleven blood samples. As a consequence, it is a simple and convenient method to determine the renal function in pediatric patients.