Glomerular Filtration Rate Estimation in Prospective Living Kidney Donors: Preliminary Study

Comparison of Different Equations with GFR Measured by Scintigraphy in Kidney Donors

Background

Technetium-99m diethylene-triamine-pentaacetate (99mTc-DTPA)-based scintigraphy is a convenient way to assess measured glomerular filtration rate (mGFR) in kidney donors. Equations have been developed to calculate GFR in the general population. This study aims to identify the best among commonly employed equations to better predict GFR when compared with scintigraphy-based mGFR. Also, the trends in mGFR values were studied over 1 year post-donation.

Materials and Methods

Thirty-four kidney donors were recruited for this study from November 2017 to November 2018 and followed-up for a year. Estimated GFR (eGFR) was calculated using the Modification of Diet in Renal Disease (MDRD) Equation, Chronic Kidney Disease Epidemiology (CKD-EPI) Collaboration equation, and Nankivell formula; the values were compared to that obtained using 99mTc-DTPA both pre-and post-donation. Correlation and agreement between the eGFR and mGFR were studied using Statistical Package for the Social Sciences (SPSS) version 23.0 and Microsoft Excel.

Results

mGFR was augmented by 32.3 ± 27.8% in the remnant kidney post-donation. The baseline mGFR, post-donation mGFR, and the quantum of its increase post-donation did not differ between overweight donors and donors with normal body mass index (BMI). mGFR correlated poorly with all the eGFR equations both pre- and post-donation. Bland-Altman analysis showed weak agreement with significant bias and variance between mGFR and all eGFR equations.

Conclusion

In Indian kidney donors, mGFR by 99mTc-DTPA scintigraphy shows poor correlation and agreement with the commonly used eGFR equations. An individualized approach is needed to assess the kidney function of live donors to minimize harm to both the recipient and the donor.

Is a Patient with Paget's Disease of Bone Suitable for Living Kidney Donation?-Decision-Making in Lack of Clinical Evidence

Living donor kidney transplantation is a widely performed medical procedure. Living kidney donation requires an in-depth health assessment of candidates. The potential living kidney donor must remain healthy after kidney removal. A consequence of donation can be a decrease in glomerular filtration rate (GFR), and donors can become at risk of developing chronic kidney disease (CKD). We present a rationale for potential living kidney donor withdrawal due to Paget's disease of bone (PDB) based on a literature review. The treatment for PDB includes the use of, for example, non-steroidal anti-inflammatory drugs (NSAIDs), which can lead to acute kidney injury (AKI) as well as CKD, or bisphosphonates, which are not recommended for patients with decreased GFR.

Organ-Specific Monitoring of Solitary Kidney after Living Donation by Using Markers of Glomerular Filtration Rate and Urinary Proteins

BACKGROUND

Effective follow-up after living kidney donation is important for maintaining the renal function of the donor. We investigated whether the estimated glomerular filtration rate (eGFR) and urinary protein and enzyme levels can provide important information regarding the state of the remaining kidney after donor nephrectomy.

METHODS

Seventy-five living donations were included (prospective/retrospective) in the study. The following parameters were measured up to 1 year after donor nephrectomy: serum creatinine and cystatin C as markers of the GFR; the high-molecular-weight urinary proteins as markers of glomerular injury; and the low-molecular-weight urinary proteins and urinary enzymes as markers of tubular function.

RESULTS

One year after kidney donation, the creatinine and cystatin C values were 1.38-fold increased than their initial values, while the eGFR was 32% lower. At that time, 38% of donors had a moderate or high risk of CKD progression. The biochemical urinary glomerular and tubular kidney markers examined showed different behaviors. After a transient increase, the glomerular proteins normalized. Conversely, the detection of low-molecular-weight urinary proteins and enzymes reflected mild tubular damage at the end of the study period.

CONCLUSIONS

Our findings suggest that for the evaluation of mild tubular damage, low-molecular-weight marker proteins should be included in the urine diagnostic of a personalized living kidney donor follow-up.

Formulas Estimating Glomerular Filtration Rate in the Evaluation of Living Kidney Donor Candidates: Comparison of Different Formulas With Scintigraphy-Measured Glomerular Filtration Rate

INTRODUCTION

Estimation of kidney function is crucial in the evaluation of living kidney donor candidates. Despite the multitude of glomerular filtration rate (GFR) formulas, no equation is universal, and none were validated in the population of kidney donors. Novel biomarkers, including beta trace protein (BTP) and cystatin C, are studied to help estimate GFR and improve the safe qualification of living kidney donors.

AIM

This study compares the accuracy of different formulas that estimate GFR with reference scintigraphy-measured GFR in the population of living kidney donor candidates.

MATERIAL AND METHODS

This study enrolled 30 healthy living kidney donor candidates. GFR was measured using the following 11 different formulas. For reference, GFR was assessed using 99m-Technetium-diethylenetriaminepentaacetic acid.

RESULTS

The accuracy of estimation was generally low in all formulas. The strongest correlation between measured GFR (mGFR) and estimated GFR (eGFR) was achieved by the Nankivell formula (R = 0.47, P = .009); however, in the group of patients with a body mass index of >25 kg/m², only the equations based on BTP had a statistically significant correlation with mGFR: White (R = 0.59; P = .016) and Poge (R = 0.53; P = .035). Bland-Altman plots revealed wide limits of agreement between eGFRs and mGFR in all groups of patients.

CONCLUSION

In living kidney donor candidates, GFR estimation formulas should be chosen individually. White formula, which is based on BTP, may be a promising tool in estimating GFR in overweight potential living kidney donor candidates. More than 1 formula and personalized choice of GFR estimation method regarding the given patient should be performed in qualification of kidney donors.

Computed Tomography Parameters and Estimated Glomerular Filtration Rate Formulas for Peridonation Living Kidney Donor Assessment

BACKGROUND

Renal function is usually described by the estimated glomerular filtration rate (eGFR). The standard method used for living kidney donor evaluation in our center is the 24-hour urine creatinine clearance (CrCl) and kidney morphology assessment with computed tomography (CT). The aim of the study was the analysis of the correlation of CrCl with 15 published eGFR formulas and morphologic CT parameters to choose the most accurate kidney function estimation method before and after donation.

METHODS

The study included 39 living donors (18 male and 21 female, aged 32-69 years; mean age, 51.4 [SD, 9.7] years). The eGFR was estimated using Cockcroft-Gault, Modification of Diet in Renal Disease 7, Modification of Diet in Renal Disease 4, Chronic Kidney Disease Epidemiology Collaboration, Mayo Clinic, Nankivell, Bjornsson, Davis-Chandler, Edward-Whyte, Walser, Gates, Hull, Jelliffe-1, Jelliffe-2, or Mawer formulas and correlated with CrCl. CT parameters (kidney dimensions, volume, vascularization) were compared with eGFR formulas.

RESULTS

The 25% to 34% (mean, 28.5% [SD, 2.3%]) decrease in eGFR after donation and its 1.5% to 5.0% (mean, 3.2% [SD, 1.0%]) increase over a year were observed. Cockcroft-Gault, Bjornsson, Hull, and Mawer equations (all including serum creatinine, age, sex, and body mass) correlated with predonation CrCl (r = 0.54, 0.53, 0.53, and 0.56, respectively; P < .001). From CT parameters, renal cortex volume correlated with CrCl (r = 0.48, P = .002) as well as the 4 abovementioned equations before donation (r = 0.65, 0.61, 0.64, and 0.74, respectively; P < .001) and during the postdonation period (12-month r = 0.59, 0.54, 0.57, and 0.70 respectively; P < .002).

CONCLUSIONS

The eGFR calculated with equations combining serum creatinine, age, sex, and body mass as well as renal cortex volume are predictive of pre- and postdonation kidney function.