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Assessment of glomerular filtration rate in children
Insights
Assessing glomerular filtration rate (GFR) in children revealed that plasma creatinine is a practical, though not perfect, indicator. Other tested methods for GFR estimation showed significant limitations compared to inulin clearance.
Area of Science:
- Pediatric Nephrology
- Renal Physiology
- Diagnostic Accuracy
Background:
- Accurate assessment of Glomerular Filtration Rate (GFR) is crucial for diagnosing and managing kidney diseases in children.
- Traditional GFR measurement using inulin clearance is invasive and complex.
- Development of reliable, non-invasive GFR estimation methods is needed.
Purpose of the Study:
- To compare the accuracy of five different methods for assessing GFR in children over one year of age.
- To evaluate these methods against standard inulin clearance values.
- To determine the most suitable GFR assessment method for clinical practice.
Main Methods:
- Comparison of plasma creatinine levels with inulin clearance.
- Analysis of 3-hour creatinine clearance values against inulin clearance.
- Evaluation of GFR estimates derived from plasma creatinine and height.
- Assessment of a combined creatinine and urea clearance formula.
- Measurement of stable plasma inulin concentration for clearance calculation.
Main Results:
- Plasma creatinine offers limited accuracy due to wide normal value ranges.
- 3-hour creatinine clearance significantly overestimates inulin clearance.
- GFR estimates from plasma creatinine and height showed poor correlation with inulin clearance.
- The combined formula (2x creatinine clearance + 1x urea clearance)/3 showed improved prediction over single clearances but was not ideal.
- Calculated inulin clearance based on stable plasma concentration differed significantly from standard values.
Conclusions:
- No tested method served as an ideal alternative to standard inulin clearance for precise GFR assessment in children.
- In most clinical scenarios, derived GFR values offer no significant advantage over simple plasma creatinine determination.
- Plasma creatinine remains a valuable, albeit imperfect, index of glomerular function in pediatric populations.
Abstract:
Five different methods of assessment of glomerular filtration rate (GFR) were compared in 500 children older than one year of age. Results of each method were compared with standard inulin clearance values: 1. An evaluation of glomerular function may be inferred from plasma creatinine levels; the validity of this inference is, however, limited because of the wide range of normal values; 2. creatinine clearance values calculated over 3 hours significantly overestimate inulin clearance values; 3. clearance values derived from plasma creatinine concentration ahd height show a poor correlation with traditionally calculated inulin clearances; 4. clearance values calculated as the sum of twice the creatinine clearance and once the urea clearance, divided by three, better predict inulin clearance than either C-creatinine or C-urea alone; 5 inulin clearance values calculated by dividing the quantity of inulin perfused by its plasma concentration, once it has become stable, differ significantly from the values obtained by the standard inulin clearance.--Of all the methods studied, none was found to be an ideal alternative to the traditional inulin clearance when a precise assessment of GFR is warranted. It is concluded that in most clinical conditions derived clearance values do not have significant advantages over the simple determination of plasma creatinine, a valuable but not infallible index of glomerular function.