Single injection clearance in the neonate.

The single injection clearance of inulin was compared to the standard clearance in neonates aged 1--20 days. In the first 3 days of life, the single injection method overestimated glomerular filtration rate by approximately 30%. From the 2nd week of life, values obtained by the two techniques were not significantly different. We conclude that caution should be paid when interpreting results obtained by the single injection technique during the very first days of life.