Assessment of glomerular filtration rate in infants. Comparison of three methods used in clinical practice

Area of Science:

• Pediatric Nephrology
• Renal Physiology

Background:

• Accurate assessment of glomerular filtration rate (GFR) is crucial for diagnosing and managing kidney conditions in infants.
• Traditional inulin clearance, the gold standard for GFR measurement, is complex and not routinely feasible in clinical practice.

Purpose of the Study:

• To compare the accuracy of three routine methods for estimating GFR in infants against the standard inulin clearance.
• To determine if any routine method provides a reliable and practical alternative to inulin clearance for pediatric GFR assessment.

Main Methods:

• Compared inulin clearance (standard) with three estimation methods in 66 infants under 1 year of age.
• Method 1: GFR estimated from plasma creatinine and height (k=0.55).
• Method 2: 3-hour creatinine clearance. Method 3: Combined creatinine and urea clearance (average).

Main Results:

• Plasma creatinine-based estimation did not reliably reflect GFR (r=0.82).
• 3-hour creatinine clearance overestimated GFR below 100 ml/min/1.73m² (r=0.77).
• Combined clearance method showed overestimation at low GFR and underestimation at high GFR (r=0.82).

Conclusions:

• No routine method reliably substitutes for inulin clearance for precise GFR measurement in infants.
• Simple 3-hour creatinine clearance offers a satisfactory and rational estimate of GFR for clinical practice in this age group.