NO EVIDENCE OF ACCELERATED LOSS OF KIDNEY FUNCTION IN LIVING KIDNEY DONORS: RESULTS FROM A CROSS-SECTIONAL FOLLOW-UP1

N1-methylnicotinamide (N1-MN) and N1-methyl-2-pyridone-5-carboxamide (2Py) are successive end products of NAD+ catabolism. N1-MN excretion in 24-h urine is the established biomarker of niacin nutritional status, and recently shown to be reduced in renal transplant recipients (RTR). However, it is unclear whether 2Py excretion is increased in this population, and, if so, whether a shift in excretion of N1-MN to 2Py can be attributed to kidney function. Hence, we assessed the 24-h urinary excretion of 2Py and N1-MN in RTR and kidney donors before and after kidney donation, and investigated associations of the urinary ratio of 2Py to N1-MN (2Py/N1-MN) with kidney function, and independent determinants of urinary 2Py/N1-MN in RTR. The urinary excretion of 2Py and N1-MN was measured in a cross-sectional cohort of 660 RTR and 275 healthy kidney donors with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Linear regression analyses were used to investigate associations and determinants of urinary 2Py/N1-MN. Median 2Py excretion was 178.1 (130.3–242.8) μmol/day in RTR, compared to 155.6 (119.6–217.6) μmol/day in kidney donors (p < 0.001). In kidney donors, urinary 2Py/N1-MN increased significantly after kidney donation (4.0 ± 1.4 to 5.2 ± 1.5, respectively; p < 0.001). Smoking, alcohol consumption, diabetes, high-density lipoprotein (HDL), high-sensitivity C-reactive protein (hs-CRP) and estimated glomerular filtration rate (eGFR) were identified as independent determinants of urinary 2Py/N1-MN in RTR. In conclusion, the 24-h urinary excretion of 2Py is higher in RTR than in kidney donors, and urinary 2Py/N1-MN increases after kidney donation. As our data furthermore reveal strong associations of urinary 2Py/N1-MN with kidney function, interpretation of both N1-MN and 2Py excretion may be recommended for assessment of niacin nutritional status in conditions of impaired kidney function.

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The evaluation of kidney function in living kidney donor candidates

Kidney360 ◽

10.34067/kid.0003052021 ◽

2021 ◽

pp. 10.34067/KID.0003052021

Author(s):

Neetika Garg ◽

Emilio D. Poggio ◽

Didier Mandelbrot

Keyword(s):

Chronic Kidney Disease ◽

Kidney Disease ◽

Creatinine Clearance ◽

Kidney Function ◽

The United States ◽

Estimated Gfr ◽

Kidney Donors ◽

Living Kidney Donors ◽

Increased Risk ◽

Measured Gfr

Living kidney donors incur a small increased risk of end-stage kidney disease (ESKD), of which pre-donation glomerular filtration rate (GFR) is an important determinant. As a result, kidney function assessment is central to the donor candidate evaluation and selection process. This article reviews the different methods of GFR assessment including estimated GFR, creatinine clearance and measured GFR, and the current guidelines on GFR thresholds for donor acceptance. Estimated GFR obtained using the 2009 Chronic Kidney Disease Epidemiology Collaboration equation, while the best of estimating estimations, tends to underestimate and has limited accuracy, especially near normal GFR values. In the United States, the Organ Procurement and Transplantation Network policy on living donation mandates either measured GFR or creatinine clearance as part of evaluation. Measured GFR is considered the gold standard, although there is some variation in performance characteristics depending on the marker and technique used. Major limitations of creatinine clearance are dependency on accuracy of timed collection, and overestimation as a result of distal tubular creatinine secretion. GFR declines with healthy aging, and most international guidelines recommend use of age-adapted selection criteria. The 2017 Kidney Disease: Improving Global Outcomes Guideline for the Evaluation and Care of Living Kidney Donors diverges from other guidelines and recommends using absolute cut-off of <60 ml/min/1.73m2 for exclusion and of ≥90 ml/min/1.73m2 for acceptance, and determination of candidacy with intermediate GFR based on long-term ESKD risk. However, several concerns for this strategy exist, including inappropriate acceptance of younger candidates due to underestimation of risk, and exclusion of older candidates whose kidney function is in fact appropriate for age. Role of cystatin C and other newer biomarkers, as well as data on impact of pre-donation GFR on not just ESKD risk but also advanced chronic kidney disease risk and cardiovascular outcomes are needed.

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Renal Collecting System Anatomy in Living Kidney Donors by Computed Tomographic Urography: Protocol Accuracy Compared to Intravenous Pyelographic and Surgical Findings

Journal of Clinical Imaging Science ◽

10.4103/2156-7514.175079 ◽

2016 ◽

Vol 6 ◽

pp. 1

Author(s):

Mohammad Kazem Tarzamni ◽

Nariman Nezami ◽

Afshar Zomorrodi ◽

Samad Fathi-Noroozlou ◽

Reza Piri ◽

...

Keyword(s):

Sensitivity And Specificity ◽

Cross Sectional Study ◽

Kappa Coefficient ◽

Cross Sectional ◽

Kidney Donors ◽

Living Kidney Donors ◽

Computed Tomographic ◽

Computed Tomography Urography ◽

Collecting System ◽

Urinary Collecting System

Objectives: To evaluate the accuracy of triple-bolus computed tomography urography (CTU) as a surrogate of intravenous pyelography (IVP) for determining the anatomy of the urinary collecting system in living kidney donors. Materials and Methods: In an analytic descriptive cross-sectional study, 36 healthy kidney donors were recruited during 12 months. Preoperative IVP and CTU were utilized to evaluate kidneys’ anatomy; major and minor calyces and variation were used as anatomical indices to compare the accuracy of CTU and IVP; the images were then compared to surgical findings. Results: Thirty-six kidney donors (92% male; mean age: 28 ± 6 years) were enrolled in this study. The kappa coefficient value was significant and almost perfect for the CTU and IVP findings in detecting the pattern of calyces (kappa coefficient 0.92, asymptotic 95% confidence interval 0.86–0.97). Anatomic variations or anomalies of the urinary collecting system included the bifid pelvis (5.6%), duplication (8.3%), and extra-renal pelvis (2.8%). Both the sensitivity and specificity of CTU in the detection of the anatomy and variations were 100%; the sensitivity and specificity of IVP were 83.3% and 100%, respectively. Conclusions: The triple-bolus preoperative CTU can be considered an alternative to IVP for assessing the anatomy of the urinary collecting system.

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