Effect of indexed glomerular filtration rate according to age

Area of Science:

• Nephrology
• Pediatric Nephrology
• Biostatistics

Background:

• Glomerular filtration rate (GFR) is a key indicator of kidney function.
• Standardization of GFR values is crucial for accurate clinical interpretation, especially in pediatric populations.
• Previous research suggests potential age-related differences in GFR normalization methods.

Purpose of the Study:

• To determine the age at which dispersion in GFR values, normalized by body surface area (BSA) and extracellular fluid volume (ECFV), becomes significant.
• To test the hypothesis that GFR normalization methods exhibit different behaviors in childhood.
• To establish an optimal age cutoff for differentiating GFR normalization approaches.

Main Methods:

• Retrospective analysis of patients aged 0-85 years with renal pathology.
• Administration of intravenous 51Cr-EDTA for GFR measurement.
• Application of specific GFR calculation formulas (Ham and Piepsz for children, Christensen and Groth for adults).
• Normalization of GFR by BSA and ECFV.

Main Results:

• Receiver Operating Characteristic (ROC) curve analysis identified 11.96 years as the age cutoff discriminating GFR normalization methods (sensitivity 0.83, specificity 0.85, area 0.902).
• Linear regression confirmed age-related differences in GFR normalization.
• Strong correlations were observed for GFR normalized by BSA and ECFV in both age groups: children under 12 years (r=0.883) and those 12 years and older (r=0.963).

Conclusions:

• Both BSA and ECFV normalization methods are suitable for children aged 12 years and older.
• Significant differences in GFR normalization exist for children younger than 12 years.
• ECFV normalization is recommended for children under 12 years for more accurate GFR assessment.