Related Experiment Video
Updated: Jul 3, 2026
Transdermal Measurement of Glomerular Filtration Rate in Mice
Published on: October 21, 2018
Validation of the Virga GFR equation in a renal transplant population
Ahmed Zahran1, Mohammad Akhtar Hossain, Mahmoud Abd Elaziz Kora
1Internal Medicine Department, Menoufiya University Hospital, Menoufiya University, Menoufiya, Egypt.
Insights
The Virga equation shows promise for estimating glomerular filtration rate (GFR) in renal transplant patients, outperforming the Cockcroft-Gault equation. However, the MDRD-IDMS equation remains superior for moderate kidney failure, while Virga excels in mild cases.
Area of Science:
- Nephrology
- Renal Physiology
- Medical Diagnostics
Background:
- The Virga equation was previously shown to outperform Cockcroft-Gault (C-G) and MDRD-IDMS formulas for estimating glomerular filtration rate (GFR) in chronic kidney disease (CKD) patients.
- Validating new GFR estimation equations is crucial for accurate patient management.
Purpose of the Study:
- To validate the performance of the Virga equation in estimating GFR among 103 renal transplant patients.
- To compare the accuracy of the Virga equation against established formulas like MDRD-IDMS and C-G in this specific population.
Main Methods:
- Inulin clearance was used as the reference standard for GFR measurement.
- The Virga, MDRD-IDMS, and C-G equations were evaluated based on error, accuracy, relative accuracy, precision, scatter, and coefficient of variance.
- Statistical comparisons were performed on the overall patient cohort and specific subgroups (e.g., CKD stages).
Main Results:
- The Virga equation demonstrated better performance than the C-G equation across all patient groups.
- The MDRD-IDMS equation showed superior accuracy compared to the Virga equation in patients with moderate kidney failure (CKD stage 3T) and in males.
- The Virga equation was superior to MDRD-IDMS in patients with mild kidney failure (CKD stage 2T).
Conclusions:
- The choice of GFR estimation equation in renal transplant patients depends on the stage of kidney function.
- MDRD-IDMS is recommended for moderate kidney failure, while the Virga equation is more accurate for mild kidney failure.
- Estimating GFR using MDRD-IDMS is not advised for patients with normal renal function due to potential underestimation.
Background:
Virga and colleagues derived a glomerular filtration rate (GFR) equation which demonstrated a superior performance over Cockcroft-Gault (C-G) and modified diet in renal disease-isotope dilution mass spectrometry (MDRD-IDMS) formulas in chronic kidney disease (CKD) patients.
Aim:
To validate the performance of the Virga equation on 103 renal transplant patients.
Methods:
We compared the performances of the MDRD-IDMS, C-G and Virga equations using inulin clearance as a reference test. Error, accuracy, relative accuracy, precision, scatter, and coefficient of variance of each equation were tested.
Results:
The mean absolute percentage error in estimated GFR by the new equation was 39.8 +/- 36.34% (mean +/- SD). Relative accuracy at 10, 30 and 50% range were 18.44, 48.54 and 73.78%, respectively. It has a bias of 0.09 +/- 0.169 and a precision of 19.69. Inulin clearance (GFR) in stages 1-4 were 106.19 +/- 14.11, 71.17 +/- 7, 42.37 +/- 8.40 and 22.92 +/- 3.48 ml/min/1.73 m(2), respectively. Comparative statistics in the overall population and in patients with transplant CKD stage 3T showed that the MDRD-IDMS equation had better accuracy. The performance of MDRD-IDMS over the Virga equation was clearly superior for males. In patients with CKD stage 2T, the Virga equation showed superiority over MDRD-IDMS. In the overall and subpopulations, the Virga equation performed better than the C-G equation.
Conclusion:
Among renal transplant patients, the results suggest that the best GFR estimate is probably obtained using the MDRD-IDMS equation in moderate kidney failure whilst the Virga formula was superior to MDRD-IDMS for patients with mild kidney failure. As in untransplanted patients, estimating GFR with the MDRD-IDMS equation is not advisable in the range of normal renal function because of its known underestimation of renal function.
Related Concept Videos
01:28Drug Dosing in Renal Diseases: Estimation of Glomerular Filtration Rate Based on Serum Creatinine Concentration
01:25Drug Dosing in Renal Diseases: Measurement of Glomerular Filtration Rate
01:25Drug Dosing in Renal Diseases: Measurement of Serum Creatinine Concentration and Clearance
01:11Renal Failure: Dose Adjustments
Reduced renal clearance and elimination rate are common outcomes of renal impairment. These alterations lead to a prolonged elimination half-life and an altered apparent volume of distribution for drugs. As a result, dosage adjustments are typically necessary to maintain optimal drug levels in the body.
However, dosage adjustments...
01:08Renal Drug Clearance: Comparison Between Renal Excretion Methods
Renal clearance is often associated with the renal glomerular filtration rate (GFR), which represents the rate at which plasma is filtered through the glomeruli in the kidney. When drug reabsorption is minimal and there is no active secretion, renal clearance is closely related to the...
01:25Drug Dosing in Renal Diseases: Dose Adjustments Based on Drug Clearance and Elimination Rate Constant