Filtration Rate In Kidney Donors Research Articles

Comparison of Creatinine Based and Kidney Volume Based Methods of Estimating Glomerular Filtration Rates in Potential Living Kidney Donors

Accurate assessment of kidney function is critical to evaluate living kidney donors. Direct glomerular filtration rate measurement using isotopes is currently the gold standard but it is complex and costly. We evaluated the performance of surrogate markers of the glomerular filtration rate in living kidney donors by comparing direct measurement of the rate to the creatinine based equation estimated rate, the kidney volume based estimated rate using a newly developed equation and creatinine clearance. We first statistically compared direct glomerular filtration rate measurement to the results of the Modification of Diet in Renal Disease (MDRD) and Chronic Kidney Disease-Epidemiology Collaboration (CKD-EPI) creatinine based equations, and to creatinine clearance in 54 potential renal donors from 2006 to 2010. In 32 donors with cross-sectional computerized tomography available we used measured functional renal volume with age, gender, weight and serum creatinine to estimate the rate based on kidney volume according to a previously reported model. Kidney volume based measurement was compared to direct glomerular filtration rate measurement and assessed against the results of the best performing creatinine based equation. In the first group of 54 donors the correlation index of the estimated glomerular filtration rate according to MDRD and CKD-EPI creatinine based equations, and to creatinine clearance was low compared to direct measurement. In the subset of 32 potential donors the kidney volume based estimated rate correlated better with direct measurement than MDRD equation results with higher accuracy (estimated 87.5% and 75.0% within 30% and 10% of direct rate measurement, respectively). To estimate the glomerular filtration rate in healthy individuals a volume based model correlated better than the MDRD equation, which is the best performing creatinine based equation used to estimate the rate. By providing a more robust estimation of the glomerular filtration rate in healthy potential kidney donors, the volume based model adds value to routine preoperative computerized tomography above that of anatomical evaluation.

Comparison of Estimating Equations for the Prediction of Glomerular Filtration Rate in Kidney Donors before and after Kidney Donation

The aim of this study is to investigate the usefulness of the GFR-estimating equations to predict renal function in kidney donors before and after transplantation. We compared the performance of 24-hour-urine–based creatinine clearance (24 hr urine-CrCl), the Cockcroft-Gault formula (eGFRCG), the Modification of Diet in Renal Disease equation (eGFRMDRD), and the Chronic Kidney Disease Epidemiology Collaboration equation (eGFRCKD-EPI) with technetium-diethylenetriaminepentaacetic acid (99mTc-DTPA) clearance (mGFR) in 207 potential kidney donors and 108 uninephric donors. Before donation, eGFRCKD-EPI showed minimal bias and did not show a significant difference from mGFR (P = 0.65, respectively) while 24 hr urine-CrCl and eGFRMDRD significantly underestimated mGFR (P<0.001 for each). Precision and accuracy was highest in eGFRCKD-EPI and this better performance was more dominant when renal function is higher than 90 mL·min−1·1.73 m−2. After kidney donation, eGFRMDRD was superior to other equations in precision and accuracy in contrast to before donation. Within individual analysis, eGFRMDRD showed better performance at post-donation compared to pre-donation, but eGFRCKD-EPI and eGFRCG showed inferior performance at post-donation. In conclusion, eGFRCKD-EPI showed better performance compared to other equations before donation. In a uninephric donor, however, eGFRMDRD is more appropriate for the estimation of renal function than eGFRCKD-EPI.

Predictors of Kidney Volume Change and Delayed Kidney Function Recovery After Donor Nephrectomy

To our knowledge the effects of preoperative kidney volume in living donors on the post-donation change in size and function of the remaining kidney have not been investigated. We studied the association between preoperative kidney volume, and volume change and delayed kidney function recovery in donors. From 2007 to 2008 we investigated 222 living donors. Kidney volume before and 6 months after surgery was estimated using the voxel count method. We analyzed correlations of kidney volume with patient characteristics, kidney function and actual kidney weight. To identify predictors of the volume increase of the remaining kidney and predictors of delayed kidney function recovery we performed regression analysis. Mean +/- SD total kidney volume was 311.9 +/- 50.6 cc and it correlated with weight, body surface area and kidney function (p <0.001). The mean volume increase in the remaining kidney was 27.6% +/- 9.7% (range 4.5% to 66.1%). Younger age (p <0.001) and lower preoperative volume of the remaining kidney (p = 0.019) were significant predictors of a greater increase in kidney volume on multiple linear regression analysis. Older age (OR 1.07, p <0.001), higher body mass index (OR 1.20, p = 0.008), lower preoperative kidney volume of the remaining kidney (OR 0.98, p = 0.003) and a lower preoperative diethylenetetramine pentaacetic acid glomerular filtration rate in the remaining kidney (OR 0.95, p = 0.017) were significant predictors of delayed kidney function recovery on multiple regression analysis. Kidney volume measured by the voxel count method was accurate and correlated with kidney function. Preoperative kidney volume is an independent predictor of the volume increase and delayed kidney function recovery in donors that could be used clinically.

Estimating Glomerular Filtration Rate in Kidney Donors: A Model Constructed with Renal Volume Measurements from Donor CT Scans

To create a model to estimate glomerular filtration rate (GFR) in healthy individuals, such as renal transplant donors, by using renal volume measurements derived from multidetector computed tomographic (CT) scans, serum creatinine level, height, weight, race, and age, and to compare the performance of this kidney volume-based model with the modification of diet in renal disease (MDRD) equation. This HIPAA-compliant retrospective study was approved by the institutional review board; informed consent was waived. Age, sex, height, weight, race, serum creatinine level, and measured GFR were recorded from 244 individuals who underwent renal donor evaluation over a 2-year period. An automated segmentation algorithm was used to measure renal parenchymal volume from CT images. GFR was measured by using urinary clearance of iodine 125 ((125)I) iothalamate. Analysis of covariance was used to model GFR measured by using (125)I-iothalamate clearance from the significant variables. The model was tested in 100 different renal donors and performance was compared with performance of the MDRD equation. Renal volume, age, serum creatinine level, and weight (P < .001) significantly correlated with GFR measured by using (125)I-iothalamate clearance. Sex (P = .6), race (P = .9), and height (P = .76) were not significant. The fitted regression model was GFR(EUn) = 70.77 - 0.444 A + 0.366 W + 0.200 V(R) - 37.317 Cr (r(2) = 0.57), where GFR(EUn) is estimated unadjusted GFR in milliliters per minute, A is age in years, W is weight in kilograms, V(R) is mean total renal volume in milliliters, and Cr is serum creatinine value in milligrams per deciliter (micromoles per liter). Correlation between renal volume-based GFR and GFR measured by using (125)I-iothalamate clearance was +0.42. The model outperformed the MDRD equation in six of six measurements. A model for estimating GFR that incorporates renal volume correlated well with measured GFR and outperformed the MDRD equation in potential living renal donors; this model could be used to estimate donor GFR from CT scans instead of measuring it by using (125)I-iothalamate clearance.

Inulin: An inadequate marker of glomerular filtration rate in kidney donors and transplant recipients?

Inulin: An inadequate marker of glomerular filtration rate in kidney donors and transplant recipients? During a systematic evaluation of stable renal transplant recipients, we noted a marked discrepancy between the inulin and creatinine clearance values. The C Cr /C In ratio was 1.02 ± 0.02 in subjects and 1.47 ± 0.15 in 20 transplant recipients. The C Cr /C In ratio of 14 living related recipients (1.51 ± 0.08) was not significantly different from that of cadaver recipients (1.37 ± 0.04). Evaluation of ten paired donors and recipients demonstrated a C Cr /C In ratio of 1.34 ± 0.06 and 1.51 ± 0.10, respectively (NS). In three donors, the C Cr /C In was 1.04 ± 0.02 before nephrectomy and 1.25 ± 0.08, 1 week after nephrectomy. The ratio in the recipients was 1.45 ± 0.13 1 week after transplantation. Other markers of glomerular filtration, urea and iodothalamate (Io), were evaluated. C urea /C Cr ratios were similar in normals, donors, and recipients (0.62, 0.62, 0.55, respectively). The C urea /C In ratio was 0.63 in normal subjects; it was, however, 0.72 ± 0.05 in donors and 0.9 ± 0.06 in recipients. C Io /C Cr and C IO /C In ratios in normal subjects were the same at 1.02 ± .04. C IO /C Cr ratio was 0.95 ± 0.04 in recipients and 0.96 ± 0.03 in donors. The C IO /C In ratio was 1.43 ± 0.08 in recipients and 1.23 ± 0.04 in donors. The data reveal a marked discrepancy between C Cr and C In in renal transplant recipients whether living related or cadaver donors, as well as in living related donors, were used. Furthermore, this discrepancy is manifest by 1 week after transplantation in both donors and recipients. Our data suggest that increased creatinine secretion is not solely responsible for this discrepancy, and that there may be an impairment to filtration of inulin at the level of the glomerulus. Back diffusion of filtered inulin, although unlikely, cannot be ruled out from the present data. L'inuline: Indicateur de filtration glomerulaire inadequat chez les donneurs de reins et les sujets transplantes. Au cours d'une etude systematique de malades transplantes, en etat stable, il a ete observe une discordance importante entre les valeurs des clearances de l'inuline et de la creatinine. Le rapport C Cr /C In est de 1,02 ± 0,02 chez les sujets normaux et de 1,47 ± 0,15 chez 20 transplantes. Ce rapport n'est pas significativement different chez 14 transplantes avec des reins de donneurs vivants apparentes (1,51 ± 0,08) et des transplantes avec des reins de cadavres (1,37 ± 0,04). L'etude de dix paires de donneurs et receveurs a montre un rapport de 1,34 ± 0,06 et 1,5 ± 0,10, respectivement (NS). Chez trois donneurs le rapport etait de 1,04 ± 0,02 avant et de 1,25 ± 0,08 une semaine apres la nephrectomie. Le rapport etait de 1,45 ± 0,13 chez les receveurs une semaine apres la transplantation. D'autres marqueurs de la filtration glomerulaire, l'uree et l'iodothalamate (Io), ont ete etudies. Le rapport C uree /C Cr est semblable chez les normaux, les donneurs et les receveurs (0,62, 0,62, et 0,55 repectivement). Le rapport C uree /C In est de 0,63 chez les sujets normaux, mais de 0,72 ± 0,05 chez les donneurs et de 0,9 ± 0,06 chez les receveurs. Les rapports C Io /C Cr et C IO /C In sont semblables chez les sujets normaux (1,02 ± 0,04). C IO /C Cr est de 0,95 ± 0,04 chez les receveurs et de 0,96 ± 0,03 chez les donneurs. Le rapport C IO /C In est de 1,43 ± 0,08 chez les receveurs et de 1,23 ± 0,04 chez les donneurs. Ces resultats revelent une discordance entre C Cr et C In chez les receveurs, que ce soit de reins de donneurs vivants ou de cadavres, et chez les donneurs apparentes. De plus, cette discordance est evidente une semaine apres la transplantation a la fois chez les donneurs et les receveurs. Nos resultats suggerent qu'une augmentation de la secretion de creatinine n'est pas seule responsable de la discordance et qu'il peut y avoir une alteration de la filtration de l'inuline dans le glomerule. La retro-diffusion de l'inuline ne peut pas etre eliminee a partir des resultats obtenus, encore qu'elle paraisse peu probable.