Determination of inulin clearance by single injection or infusion in children

Area of Science:

• Pediatric Nephrology
• Renal Physiology
• Diagnostic Methods

Background:

• Glomerular filtration rate (GFR) is a key indicator of kidney function in children.
• The reference method for GFR determination involves urinary clearance of inulin via continuous intravenous infusion.
• Plasma clearance of inulin offers an alternative that avoids urine collection.

Purpose of the Study:

• To compare the accuracy and practicality of two inulin plasma clearance methods in pediatric patients.
• To evaluate the single injection method against the established continuous infusion technique for GFR assessment.

Main Methods:

• Inulin plasma clearance was measured in 24 pediatric patients using two distinct methods.
• Method 1: Single injection of inulin (5000 mg/m²) followed by blood sampling at 10, 30, 90, and 240 minutes.
• Method 2: Overnight continuous intravenous infusion of inulin with subsequent blood sample collection.

Main Results:

• The single injection method yielded an average inulin plasma clearance 9.7 ml/min/1.73 m² higher than the continuous infusion method (95% CI: 5.3-14.2).
• The discrepancy between the two methods was less pronounced in children with lower GFRs.
• The observed differences are considered clinically acceptable for pediatric GFR assessment.

Conclusions:

• The single injection method for inulin plasma clearance is a viable and practical alternative for pediatric GFR determination.
• This method simplifies the assessment process by minimizing blood sampling requirements.
• The single injection method is recommended for clinical practice due to its convenience and acceptable accuracy.