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Estimation of glomerular filtration rate from plasma creatinine concentration in children
Insights
A new formula accurately estimates glomerular filtration rate (GFR) using plasma creatinine and height, outperforming 24-hour creatinine clearance tests for children. This provides a more reliable measure of kidney function.
Area of Science:
- Pediatric Nephrology
- Clinical Chemistry
- Biostatistics
Background:
- Accurate assessment of glomerular filtration rate (GFR) is crucial for diagnosing and managing kidney disease in children.
- Traditional methods like 24-hour creatinine clearance can be cumbersome and prone to collection errors.
Purpose of the Study:
- To derive and validate a novel formula for estimating GFR corrected for body surface area (GFR/SA) using plasma creatinine concentration (Pc) and height (Ht).
- To compare the accuracy and precision of the new formula against the 24-hour creatinine clearance in a pediatric population.
Main Methods:
- A formula was derived: GFR/SA (ml/min per 1.73m²SA) = 0.43 Ht (cm)/Pc (mg/100 ml) in a group of 108 individuals.
- The derived formula was then tested and validated in a separate group of 83 children.
- Comparison with 24-hour creatinine clearance was performed to assess accuracy and precision.
Main Results:
- The novel formula demonstrated superior overall accuracy and precision compared to 24-hour creatinine clearance.
- Even when excluding data from potentially inaccurate 24-hour urine collections, the formula's performance remained comparable or superior.
- The formula in SI units is GFR/SA (ml/min per 1.73 m²SA) = 38 Ht (cm)/Pc (µmol/l).
Conclusions:
- The new formula provides a reliable and more accurate method for estimating GFR/SA in children.
- This simplified estimation method may reduce reliance on less accurate and more labor-intensive 24-hour urine collections.
- The validated formula offers a practical tool for pediatric nephrology and clinical practice.
Abstract:
The relation between the true plasma creatinine concentration (Pc) and the glomerular filtration rate corrected for body surface area (GFR/SA) was investigated in 108 individuals, and the following formula was derived: GFR/SA (ml/min per 1-73m2SA) = 0-43 Ht (cm)/Pc (mg/100 ml). This formula was tested in a second group of 83 children, and its accuracy and precision was compared to the 24-hour creatinine clearance. It was found to be superior to the creatinine clearance overall, and was as good, even if all results involving suspect 24-hour-urine collections were eliminated from analysis. The formula in SI usage is: GFR/SA (ml/min per 1-73 m2SA) = 38 Ht (cm)1Pc (mumol/l).