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Updated: Jan 4, 2026
Transcutaneous Assessment of Renal Function in Conscious Rodents
Published on: March 26, 2016
[Basal renal function in paediatric patients: correlation of methods that depend on a 24h urine collection with
Mercedes Ubetagoyena Arrieta1, Ramón Areses Trapote1, Jone Mendia Ubetagoyena1
1Sección de Nefrología Pediátrica, Hospital Universitario Donostia, San Sebastián, España.
Insights
Schwartz equations offer a reliable, accessible method for assessing pediatric renal function without 24-hour urine collection. These equations correlate well with measured creatinine clearance, simplifying kidney function tests.
Area of Science:
- Pediatric Nephrology
- Clinical Chemistry
- Renal Physiology
Background:
- Accurate assessment of renal function is crucial in pediatric clinical practice.
- Current methods for estimating glomerular filtration rate (GFR) can be time-consuming.
- There is a need for quick, accessible methods to evaluate kidney function in children.
Purpose of the Study:
- To evaluate the relationship and concordance between 24-hour urine creatinine clearance (CCr) and Schwartz equations (SE) for GFR estimation.
- To correlate urine excretion of substances with blood and urine concentration parameters.
Main Methods:
- Study involved 401 healthy children aged 3-14 years.
- Pearson correlation coefficient and intraclass correlation coefficient (ICC) were used for analysis.
- Compared original and modified Schwartz equations against 24-hour urine creatinine clearance.
Main Results:
- Modified Schwartz equation showed higher correlation (r=0.68, ICC=0.78) with CCr than the original (r=0.58, ICC=0.74).
- Strong correlations were found between 24-hour urine sodium/potassium excretion and fractional excretion (r=0.8-0.85).
- Urine volume correlated highly with GFR (r=0.88).
Conclusions:
- Schwartz equations provide valuable insights into basal renal function.
- These equations eliminate the need for timed urine collection for GFR assessment.
- The findings support the use of Schwartz equations for routine pediatric renal function evaluation.
Introduction:
In daily clinical practice a quick, easy and accessible method is needed to adequately assess renal function. The objectives of this study were: 1. To quantify the relationship and concordance of the glomerular filtration rate (GF) calculated by the clearance of creatinine in 24h urine (CCr) and the original and modified Schwartz equation (SE); and 2. To correlate urine elimination of substances that depends on the volume of excreted urine in a unit of time with other parameters that are calculated measuring the concentration of these substances in blood and urine.
Material And Methods:
The study included 401 healthy children with ages between 3 to 14 years (187 male and 214 female). The analysis between the variables was carried out using Pearson's correlation coefficient and the intraclass correlation coefficient (ICC).
Results:
The correlation between values of CCr and the original SE (non-standardised creatinine measurement) was r=0.58 (P<0.001) and the concordance, ICC=0.74. The correlation between CCr values and the modified SE (standardised creatinine measurement) was r=0.68 (P<.001), and the concordance ICC=0.78. There was a very significant correlation between the elimination of sodium in a 24h urine (mEq/kg/24h) and the Na-Fractional-Excretion (EFNa): r=0.8 (P<.001). There was a correlation between the potassium elimination in 24h (mEq/kg/24h) and EFK: r=0.85 (P<.001). Between volume/min/1.73m2 and the urine volume percent of GF was: r=0.88 (P<.001).
Conclusions:
These equations provide valuable information of the state of the basal renal function without having to use a timed urine.
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