Hypertension after kidney donation: Incidence, predictors, and correlates

Potassium-Alkali-Enriched Diet, Hypertension, and Proteinuria following Uninephrectomy

Key Points

A K-alkali–enriched diet blunted post-uninephrectomy hypertension and facilitated acid clearance by suppressing Na+ reabsorption. Uninephrectomy-associated proteinuria could be attributed to elevated single-nephron GFR and downregulation of megalin, which reduced fractional protein endocytosis.

Background

Losing or donating a kidney is associated with risks of developing hypertension and albuminuria. Few studies address mechanisms or interventions. We investigate the potential benefits of a K+- alkali–enriched diet and the mechanisms underlying proteinuria.

Methods

Male Sprague Dawley rats were fed either a 2% NaCl+0.95% KCl diet (HNa-LK) or a 0.74% NaCl+3% K+-alkali diet (HK-alk) for 3 weeks before uninephrectomy and then maintained on respective diets for 12 weeks. BP (by tail-cuff), urine, blood, and kidney proteins were analyzed before and after uninephrectomy.

Results

Before uninephrectomy, HK-alk–fed versus HNa-LK–fed rats exhibited similar BPs and plasma [K+], [Na+], but lower proximal (NHE3, sodium bicarbonate cotransporter 1, NaPi2) and higher distal (NCC, ENaC, and pendrin) transporter abundance, a pattern facilitating K+ and HCO3− secretion. After uninephrectomy, single-nephron GFR increased 50% and Li+ clearance doubled with both diets; in HK-alk versus HNa-LK, the increase in BP was less and ammoniagenesis was lower, abundance of proximal tubule transporters remained lower, ENaC-α fell, and NCCp increased, consistent with K+ conservation. After uninephrectomy, independent of diet, albuminuria increased eight-fold and abundance of endocytic receptors was reduced (megalin by 44%, disabled homolog 2 by 25%–35%) and kidney injury molecule-1 was increased.

Conclusions

The K-alkali–enriched diet blunted post-uninephrectomy hypertension and facilitated acid clearance by suppressing proximal Na+ transporters and increasing K+-alkali secretion. Furthermore, uninephrectomy-associated proteinuria could be attributed, at least in part, to elevated single-nephron GFR coupled with downregulation of megalin, which reduced fractional protein endocytosis and Vmax.

Podcast

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Evaluation and Long-Term Follow-Up of Living Kidney Donors

The evaluation of living kidney donor candidates is a complex and lengthy process. Donor candidates face geographic and socioeconomic barriers to completing donor evaluation. Inequities in access to living donations persist. With a growing demand for kidney transplants and a shortage of living donors, transplant centers are more permissive of accepting less-than-ideal donor candidates. Donors have an increased lifetime risk of kidney failure, but the absolute risk increase is small. Efforts are needed to support donor candidates to complete donor nephrectomy safely and efficiently and receive optimal follow-up care to prevent risk factors for kidney disease and detect complications early. In this article, the authors address key elements of donor kidney evaluation, including current living donation policy requirements and transplant center practices. The authors present a simplified comprehensive practical approach to help guide providers in completing donor evaluation and follow-up care with best outcomes possible.

Longitudinal Trajectories of Estimated Glomerular Filtration Rate in a European Population of Living Kidney Donors

A living donor (LD) kidney transplant is the best treatment for kidney failure, but LDs safety is paramount. We sought to evaluate our LDs cohort's longitudinal changes in estimated glomerular filtration rate (eGFR). We retrospectively studied 320 LDs submitted to nephrectomy between 1998 and 2020. The primary outcome was the eGFR change until 15 years (y) post-donation. Subgroup analysis considered distinct donor characteristics and kidney function reduction rate (%KFRR) post-donation [-(eGFR6 months(M)-eGFRpre-donation)/eGFRpre-donation*100]. Donors had a mean age of 47.3 ± 10.5 years, 71% female. Overall, LDs presented an average eGFR change 6 M onward of +0.35 mL/min/1.73 m2/year. The period with the highest increase was 6 M-2 Y, with a mean eGFR change of +0.85L/min/1.73 m2/year. Recovery plateaued at 10 years. Normal weight donors presented significantly better recovery of eGFR +0.59 mL/min/1.73 m2/year, compared to obese donors -0.18L/min/1.73 m2/year (p = 0.020). Noteworthy, these results only hold for the first 5 years. The subgroup with a lower KFRR (<26.2%) had a significantly higher decrease in eGFR overall of -0.21 mL/min/1.73 m2/year compared to the groups with higher KFRR (p < 0.001). These differences only hold for 6 M-2 Y. Moreover, an eGFR<50 mL/min/1.73 m2 was a rare event, with ≤5% prevalence in the 2-15 Y span, correlating with eGFR pre-donation. Our data show that eGFR recovery is significant and may last until 10 years post-donation. However, some subgroups presented more ominous kidney function trajectories.

Risk Factors for Developing Low Estimated Glomerular Filtration Rate and Albuminuria in Living Kidney Donors

Rationale & Objective

Chronic kidney disease is associated with significant morbidity and mortality in the general population, but little is known about the incidence and risk factors associated with developing low estimated glomerular filtration rate (eGFR) and moderate-severe albuminuria in living kidney donors following nephrectomy.

Study Design

Retrospective, population-based cohort study.

Setting & Participants

Kidney donors in Alberta, Canada.

Exposure

Donor nephrectomy between May 2001 and December 2017.

Outcome

Two eGFR measurements <45 mL/min/1.73 m2 or 2 measurements of moderate or severe albuminuria from 1-year postdonation onwards that were at least 90 days apart.

Analytical Approach

Associations between potential risk factors and the primary outcome were assessed using Cox proportional hazard regression analyses.

Results

Over a median follow-up period of 8.6 years (IQR, 4.7-12.6 years), 47 of 590 donors (8.0%) developed sustained low eGFR or moderate-severe albuminuria with an incidence rate of 9.2 per 1,000 person-years (95% confidence interval, 6.6-11.8). The median time for development of this outcome beyond the first year after nephrectomy was 2.9 years (IQR, 1.4-8.0 years). Within the first 4 years of follow-up, a 5 mL/min/1.73 m2 lower predonation eGFR increased the hazard of developing postdonation low eGFR or moderate-severe albuminuria by 26% (adjusted HR, 1.26; 95% CI, 1.10-1.44). Furthermore, donors were at higher risk of developing low eGFR or albuminuria if they had evidence of predonation hypertension (adjusted HR, 2.52; 95% CI, 1.28-4.96) or postdonation diabetes (adjusted HR, 4.72; 95% CI, 1.54-14.50).

Limitations

We lacked data on certain donor characteristics that may affect long-term kidney function, such as race, smoking history, and transplant-related characteristics.

Conclusions

A proportion of kidney donors at an incidence rate of 9.2 per 1,000 person-years will develop low eGFR or albuminuria after donation. Donors with lower predonation eGFR, predonation hypertension, and postdonation diabetes are at increased risk of developing this outcome.

No difference in follow-up estimated glomerular filtration rate between hypertensive and matched nonhypertensive kidney donors

BACKGROUND

According to current guidelines, kidney donor candidates with controlled hypertension using 1 or 2 antihypertensive drugs may be considered as donor. However, this recommendation is based on the study that antihypertensive drug was initiated in mainly "after donor registration" and this may be white-coat hypertension because of donation-related anxiety. We compared the follow-up eGFR between kidney donors with preexisting hypertension and matched nonhypertensive donors.

METHODS

This single-center retrospective study classified 97 living hypertensive donors previously receiving antihypertensive drugs into two groups: 1 drug group (61 donors) and 2 drugs group (36 donors). We compared the follow-up eGFR between each donor previously receiving antihypertensive drugs and three matched nonhypertensive donors in terms of age, sex, and follow-up duration.

RESULTS

At a mean (range) of 51 months (12-214) in the 1 drug group, and 54 months (12-175) in the 2 drugs group after donation, there was no significant difference in follow-up eGFR between hypertensive donors previously receiving antihypertensive drugs and matched controls in each group and in total donors. There was no difference in the incidence of the patients with follow-up eGFR<45mL/min/m2 in each group and their matched controls. Multiple linear regression analysis showed that baseline eGFR was the only independent predictor for the final follow-up eGFR in the total donors.

CONCLUSION

Our results support the current guidelines that donor candidates with controlled hypertension using 1 or 2 antihypertensive drugs may be considered as donors, and may increase the strength of this recommendation.

Living kidney donors with HIV: experience and outcomes from a case series by the HOPE in Action Consortium

Background

Living kidney donation is possible for people living with HIV (PLWH) in the United States within research studies under the HIV Organ Policy Equity (HOPE) Act. There are concerns that donor nephrectomy may have an increased risk of end-stage renal disease (ESRD) in PLWH due to HIV-associated kidney disease and antiretroviral therapy (ART) nephrotoxicity. Here we report the first 3 cases of living kidney donors with HIV under the HOPE Act in the United States.

Methods

Within the HOPE in Action Multicenter Consortium, we conducted a prospective study of living kidney donors with HIV. Pre-donation, we estimated the 9-year cumulative incidence of ESRD, performed genetic testing of apolipoprotein L1 (APOL1), excluding individuals with high-risk variants, and performed pre-donation kidney biopsies (HOPE Act requirement). The primary endpoint was ≥grade 3 nephrectomy-related adverse events (AEs) in year one. Post-donation, we monitored glomerular filtration rate (measured by iohexol/Tc-99m DTPA [mGFR] or estimated with serum creatinine [eGFR]), HIV RNA, CD4 count, and ART.

Findings

There were three donors with two-four years of follow-up: a 35 year-old female, a 52 year-old male, and a 47 year-old male. Pre-donation 9-year estimated cumulative incidence of ESRD was 3.01, 8.01, and 7.76 per 10,000 persons, respectively. In two donors with APOL1 testing, no high-risk variants were detected. Biopsies from all three donors showed no kidney disease. Post-donation, two donors developed nephrectomy-related ≥grade 3 AEs: a medically-managed ileus and a laparoscopically-repaired incisional hernia. GFR declined from 103 to 84 mL/min/1.73 m2 at four years (mGFR) in donor 1, from 77 to 52 mL/min/1.73 m2 at three years (eGFR) in donor 2, and from 65 to 39 mL/min/1.73 m2 at two years (eGFR) in donor 3. HIV RNA remained <20 copies/mL and CD4 count remained stable in all donors.

Interpretation

The first three living kidney donors with HIV under the HOPE Act in the United States have had promising outcomes at two-four years, providing proof-of-concept to support living donation from PLWH to recipients with HIV.

Funding

National Institute of Allergy and Infectious Diseases, National Institutes of Health.

Development and Validation of a Hypertension Risk Calculator for Living Kidney Donors

BACKGROUND

Ideally, when deciding whether to donate, kidney donor candidates would understand their long-term risks. Using single-center data (N = 4055; median [quartiles] follow-up: 18 [9-28] y), we developed a calculator for postdonation hypertension and validated it using long-term data from an external single-center cohort (N = 1189, median [quartiles] follow-up: 9 [5-17] y).

METHODS

Risk factors considered were routinely obtained at evaluation from donor candidates. Two modeling approaches were evaluated: Cox proportional hazards and random survival forest models. Cross-validation prediction error and Harrell's concordance-index were used to compare accuracy for model development. Top-performing models were assessed in the validation cohort using the concordance-index and net reclassification improvement.

RESULTS

In the development cohort, 34% reported hypertension at a median (quartiles) of 16 (8-24) y postdonation; and in the validation cohort, 29% reported hypertension after 17 (10-22) y postdonation. The most accurate model was a Cox proportional hazards model with age, sex, race, estimated glomerular filtration rate, systolic and diastolic blood pressure, body mass index, glucose, smoking history, family history of hypertension, relationship with recipient, and hyperlipidemia (concordance-index, 0.72 in the development cohort and 0.82 in the validation cohort).

CONCLUSIONS

A postdonation hypertension calculator was developed and validated; it provides kidney donor candidates, their family, and care team a long-term projection of hypertension risk that can be incorporated into the informed consent process.

Recommendations for living donor kidney transplantation

This Guide for Living Donor Kidney Transplantation (LDKT) has been prepared with the sponsorship of the Spanish Society of Nephrology (SEN), the Spanish Transplant Society (SET), and the Spanish National Transplant Organization (ONT). It updates evidence to offer the best chronic renal failure treatment when a potential living donor is available. The core aim of this Guide is to supply clinicians who evaluate living donors and transplant recipients with the best decision-making tools, to optimise their outcomes. Moreover, the role of living donors in the current KT context should recover the level of importance it had until recently. To this end the new forms of incompatible HLA and/or ABO donation, as well as the paired donation which is possible in several hospitals with experience in LDKT, offer additional ways to treat renal patients with an incompatible donor. Good results in terms of patient and graft survival have expanded the range of circumstances under which living renal donors are accepted. Older donors are now accepted, as are others with factors that affect the decision, such as a borderline clinical history or alterations, which when evaluated may lead to an additional number of transplantations. This Guide does not forget that LDKT may lead to risk for the donor. Pre-donation evaluation has to centre on the problems which may arise over the short or long-term, and these have to be described to the potential donor so that they are able take them into account. Experience over recent years has led to progress in risk analysis, to protect donors' health. This aspect always has to be taken into account by LDKT programmes when evaluating potential donors. Finally, this Guide has been designed to aid decision-making, with recommendations and suggestions when uncertainties arise in pre-donation studies. Its overarching aim is to ensure that informed consent is based on high quality studies and information supplied to donors and recipients, offering the strongest possible guarantees.

Long-term Medical Outcomes of Living Kidney Donors

Historically, to minimize risks, living kidney donors have been highly selected and healthy. Operative risks are well-defined, yet concern remains about long-term risks. In the general population, even a mild reduction in glomerular filtration rate (GFR) is associated with cardiovascular disease, chronic kidney disease, and end-stage kidney disease (ESKD). However, reduction in GFR in the general population is due to kidney or systemic disease. Retrospective studies comparing donors with matched general population controls have found no increased donor risk. Prospective studies comparing donors with controls (maximum follow-up, 9 years) have reported that donor GFR is stable or increases slightly, whereas GFR decreases in controls. However, these same studies identified metabolic and vascular donor abnormalities. There are a few retrospective studies comparing donors with controls. Each has limitations in selection of the control group, statistical analyses, and/or length of follow-up. One such study reported increased donor mortality; 2 reported a small increase in absolute risk of ESKD. Risk factors for donor ESKD are similar to those in the general population. Postdonation pregnancies are also associated with increased risk of hypertension and preeclampsia. There is a critical need for long-term follow-up studies comparing donors with controls from the same era, geographic area, and socioeconomic status who are healthy, with normal renal function on the date matching the date of donation, and are matched on demographic characteristics with the donors. These data are needed to optimize donor candidate counseling and informed consent.

Hypertension in chronic kidney disease: What lies behind the scene

Hypertension is a frequent condition encountered during kidney disease development and a leading cause in its progression. Hallmark factors contributing to hypertension constitute a complexity of events that progress chronic kidney disease (CKD) into end-stage renal disease (ESRD). Multiple crosstalk mechanisms are involved in sustaining the inevitable high blood pressure (BP) state in CKD, and these play an important role in the pathogenesis of increased cardiovascular (CV) events associated with CKD. The present review discusses relevant contributory mechanisms underpinning the promotion of hypertension and their consequent eventuation to renal damage and CV disease. In particular, salt and volume expansion, sympathetic nervous system (SNS) hyperactivity, upregulated renin–angiotensin–aldosterone system (RAAS), oxidative stress, vascular remodeling, endothelial dysfunction, and a range of mediators and signaling molecules which are thought to play a role in this concert of events are emphasized. As the control of high BP via therapeutic interventions can represent the key strategy to not only reduce BP but also the CV burden in kidney disease, evidence for major strategic pathways that can alleviate the progression of hypertensive kidney disease are highlighted. This review provides a particular focus on the impact of RAAS antagonists, renal nerve denervation, baroreflex stimulation, and other modalities affecting BP in the context of CKD, to provide interesting perspectives on the management of hypertensive nephropathy and associated CV comorbidities.

Perceived Susceptibility to Chronic Kidney Disease and Hypertension Self-Management among Black and White Live Kidney Donors

Background

Despite the societal benefits of live kidney donation, Black donors may be more likely than White donors to develop hypertension (HTN) and chronic kidney disease after donation. Among live kidney donors diagnosed with post-donation HTN, little is known about potential racial/ethnic differences in HTN self-care behaviors and perceived susceptibility to developing kidney disease.

Methods

We ascertained electronic medical records and phone survey data from live donors enrolled in the multi-center Wellness and Health Outcomes of LivE Donors (WHOLE-Donor) Hypertension Care Study between May 2013 and April 2020. Using multivariable logistic regression models performed January through June 2021, we examined potential associations of donor race/ethnicity with perceived susceptibility to kidney disease and self-care behaviors (ie, Behavioral Risk Factor Surveillance System measure assessing self-reported actions to control high blood pressure).

Results

The study included 318 US-based live kidney donors who developed post-donation HTN (57.6% female; 78.9% White; 18.6% Black; and mean age 46.7 years at donation). Black donors were equally as likely as White donors to report being moderately or strongly concerned about developing kidney disease (adjusted odds ratio, aOR: 1.27, 95%CI: .66, 2.14, P=.57). Donors with diabetes were more likely than those without diabetes (aOR: 2.43, 95%CI: 1.03, 5.01, P=.04), while donors aged >50 years were less likely than younger donors (aOR: .39, 95%CI: .18, .85, P=.02) to report being moderately or strongly concerned about kidney disease. Overall, 87% of donors reported taking at least one action to help control blood pressure, with no significant differences by sociodemographic factors.

Conclusions

We found no substantial differences in perceived susceptibility to kidney disease among Black and White donors, despite published evidence that Black donors may experience greater risk of developing kidney disease than White donors. Behavioral interventions to enhance knowledge about future disease risk, attitudes, and self-care strategies among living kidney donors may be beneficial.

New onset hypertension after transplantation

It has been reported that up to 90% of organ transplant recipients have suboptimal blood pressure control. Uncontrolled hypertension is a well-known culprit of cardiovascular and overall morbidity and mortality. In addition, rigorous control of hypertension after organ transplantation is a crucial factor in prolonging graft survival. Nevertheless, hypertension after organ transplantation encompasses a broader range of causes than those identified in non-organ transplant patients. Hence, specific management awareness of those factors is mandated. An in-depth understanding of hypertension after organ transplantation remains a debatable issue that necessitates further clarification. This article provides a comprehensive review of the prevalence, risk factors, etiology, complications, prevention, and management of hypertension after organ transplantation.

Experimental uninephrectomy associates with less parasympathetic modulation of heart rate and facilitates sodium-dependent arterial hypertension

Background

Blood pressure is known to be increased in kidney donors following living-donor kidney transplantation. However, the physiological underpinnings of the blood-pressure increase following uninephrectomy remain unclear. We hypothesized that changes in sympathetic tone or in parasympathetic modulation of sinus node function are involved in the blood-pressure increase following experimental kidney-mass reduction.

Methods

C57BL6N mice (6 to 11 per group) subjected to sham surgery (controls) or uninephrectomy with or without a one-week course of sodium chloride-enriched, taurine-deficient diet were studied. Uninephrectomized mice treated with a subcutaneous infusion of angiotensin-II over a period of one week were positive controls. A transfemoral aortic catheter with telemetry unit was implanted, readings of heart-rate and blood-pressure were recorded. Powerspectral analysis of heart rate and systolic blood pressure was performed to gain surrogate parameters of sympathetictone and parasympathetic modulation of sinus node function. Baroreflex sensitivity of heart rate was determined from awake, unrestrained mice using spontaneous baroreflex gain technique.

Results

Systolic arterial blood pressure, heart rate and baroreflex sensitivity were not different in uninephrectomized mice when compared to controls. Parasympathetic modulation of sinus node function was less in uninephrectomized mice in comparison to controls. Uninephrectomized mice of the high-angiotensin-II model or of the high-salt and taurine-deficiency model had an increased systolic arterial blood pressure.

Conclusions

Uninephrectomy associated with less parasympathetic modulation of sinus node function. The combination of uninephrectomy, taurine-deficiency and high-salt intake led to arterial hypertension.

Intermediate Renal Outcomes, Kidney Failure, and Mortality in Obese Kidney Donors

BACKGROUND

Obesity is associated with the two archetypal kidney disease risk factors: hypertension and diabetes. Concerns that the effects of diabetes and hypertension in obese kidney donors might be magnified in their remaining kidney have led to the exclusion of many obese candidates from kidney donation.

METHODS

We compared mortality, diabetes, hypertension, proteinuria, reduced eGFR and its trajectory, and the development of kidney failure in 8583 kidney donors, according to body mass index (BMI). The study included 6822 individuals with a BMI of <30 kg/m2, 1338 with a BMI of 30-34.9 kg/m2, and 423 with a BMI of ≥35 kg/m2. We used Cox regression models, adjusting for baseline covariates only, and models adjusting for postdonation diabetes, hypertension, and kidney failure as time-varying covariates.

RESULTS

Obese donors were more likely than nonobese donors to develop diabetes, hypertension, and proteinuria. The increase in eGFR in obese versus nonobese donors was significantly higher in the first 10 years (3.5 ml/min per 1.73m2 per year versus 2.4 ml/min per 1.73m2 per year; P<0.001), but comparable thereafter. At a mean±SD follow-up of 19.3±10.3 years after donation, 31 (0.5%) nonobese and 12 (0.7%) obese donors developed ESKD. Of the 12 patients with ESKD in obese donors, 10 occurred in 1445 White donors who were related to the recipient (0.9%). Risk of death in obese donors was not significantly increased compared with nonobese donors.

CONCLUSIONS

Obesity in kidney donors, as in nondonors, is associated with increased risk of developing diabetes and hypertension. The absolute risk of ESKD is small and the risk of death is comparable to that of nonobese donors.

Practice Patterns in the Acceptance of Medically Complex Living Kidney Donors with Obesity, Hypertension, Family History of Kidney Disease, or Donor-Recipient Age Discrepancy

Background  To assess the practice patterns of the acceptance of medically complex living kidney donors (MCLKDs). Methods  We distributed a survey to nephrologists and transplant surgeons (TS) across the world through major international transplant societies. The survey contained questions regarding obesity, abnormal blood glucose profile, mild hypertension, donor-recipient age discrepancy, or family history of kidney disease of unknown etiology. Results  In total, 239 respondents from 29 countries (42% were nephrologists and 58% were TS). Most respondents would allow donations from obese donors, especially if they intended to lose weight but would be cautious if these donors had abnormal blood glucose or family history of diabetes mellitus. In hypertensive donors, future pregnancy plans mattered in decisions regarding the acceptance of female donors. Most respondents would allow young donors but would be more cautious if they had a future risk of hypertension or a family history of kidney disease of unknown etiology. They would also allow donations from an older person if prolonged waiting time was anticipated. We found multiple areas of consensus of practice among the diverse members of international transplant societies, with some interesting variations among nephrologists and TS. Conclusions  This survey highlights the practice patterns of the acceptance of MCLKDs among the international community. In the absence of clear guidelines, this survey provides additional information to counsel kidney donors with these conditions.

Hypertension and renal outcomes in normotensive kidney donors with multiple renal arteries

Having multiple renal arteries (MRA) has been linked to hypertension development. Whether kidney donors who are left with MRA in the nondonated kidney incur a higher risk of hypertension has not been studied. We compared the development of hypertension, reduced estimated glomerular filtration rate (eGFR), cardiovascular disease, and mortality in 2624 normotensive kidney donors with MRA in the nondonated kidney and to 2624 propensity score matched normotensive donor controls with a single renal artery. In total, 35% of donors had MRA. Donors with MRA were less likely to have undergone a left nephrectomy (51% vs. 83%). Postdonation hypertension was associated with age, male gender, non-White ethnicity, obesity, and family history of hypertension. Having MRA was not associated with risk of hypertension; aHR 0.92 (95% CI 0.82-1.03), P = 0.16. After 17 ± 11 years from donation, a similar proportion of donors with and without MRA developed cardiovascular disease, proteinuria and eGFR <30, <45 and <60 mL/min/1.73 m² and the multivariable risks of developing these outcomes were similar in the two groups. Our study did not show increased risk for hypertension, reduced eGFR, proteinuria or cardiovascular disease in donors with MRA in the remaining kidney and without hypertension at donation.

Living donation - any news on the donor?

PURPOSE OF REVIEW

Living kidney donation has been an established practice for many years. Although studies from the past decade have uncovered risks to the donor, living kidney donation is still promoted. In this review, the most recent studies are summarized.

RECENT FINDINGS

Retrospective studies with long follow-up have detected an increased risk of hypertension among donors. Donors with hypertension at the time of donation may be at increased risk of adverse outcomes, but results differ. Recent studies have not found increased long-term mortality, but follow-up is short and control groups are of different quality.

SUMMARY

In all, the most recent findings more or less corroborate previous knowledge in the field of living donation. There is still a need for new studies on mortality with appropriate control groups and long enough follow-up.

Outcomes of Hypertensive Kidney Donors Using Current and Past Hypertension Definitions

Introduction

As many as 50% of U.S. transplant centers do not accept kidney donor candidates with hypertension, citing the link between hypertension, kidney disease, and cardiovascular disease (CVD).

Methods

We ascertained mortality, CVD, proteinuria, estimated glomerular filtration rate (eGFR) trajectory, reduced eGFR, and end-stage kidney disease (ESKD) in 904 hypertensive donors (blood pressure [BP] ≥140/90 mm Hg or receiving treatment) versus 7817 donors with BP <140/90 mm Hg.

Results

Hypertensive donors were older, 58.1% were <50 years of age, and they had a lower eGFR. The majority were white and related to their recipient. At the end of follow-up, 14.3 ± 10.1 years (range 4-48 years) from donation, hypertensive and nonhypertensive donors had a similar prevalence of cardiovascular disease and renal outcomes. The multivariable risk of mortality, CVD, and proteinuria were also comparable in normotensive and hypertensive donors. eGFR slope over time was similar in hypertensive and nonhypertensive donors, and in total 5 hypertensive and 39 normotensive donors developed ESKD 19.2 ± 10.3 years after donation (adjusted hazard ratio 1.14 [95% confidence interval 0.62-2.12], P = 0.67). Sensitivity analysis using the new definition of hypertension (≥130/80 mm Hg or requiring treatment) yielded similar results for renal outcomes, but hypertensive donors were more likely to develop CVD and diabetes.

Conclusions

Kidney donors with hypertension defined by past criteria do not appear to incur higher mortality, CVD, or ESKD. Donors with current definition of hypertension enjoyed similar renal outcomes but were more likely to develop CVD.

Increased SGK1 activity potentiates mineralocorticoid/NaCl-induced kidney injury

Serum and glucocorticoid-regulated kinase 1 (SGK1) stimulates aldosterone-dependent renal Na⁺ reabsorption and modulates blood pressure. In addition, genetic ablation or pharmacological inhibition of SGK1 limits the development of kidney inflammation and fibrosis in response to excess mineralocorticoid signaling. In this work, we tested the hypothesis that a systemic increase in SGK1 activity would potentiate mineralocorticoid/salt-induced hypertension and kidney injury. To that end, we used a transgenic mouse model with increased SGK1 activity. Mineralocorticoid/salt-induced hypertension and kidney damage was induced by unilateral nephrectomy and treatment with deoxycorticosterone acetate and NaCl in the drinking water for 6 wk. Our results show that although SGK1 activation did not induce significantly higher blood pressure, it produced a mild increase in glomerular filtration rate, increased albuminuria, and exacerbated glomerular hypertrophy and fibrosis. Transcriptomic analysis showed that extracellular matrix- and immune response-related terms were enriched in the downregulated and upregulated genes, respectively, in transgenic mice. In conclusion, we propose that systemically increased SGK1 activity is a risk factor for the development of mineralocorticoid-dependent kidney injury in the context of low renal mass and independently of blood pressure.NEW & NOTEWORTHY Increased activity of the protein kinase serum and glucocorticoid-regulated kinase 1 may be a risk factor for accelerated renal damage. Serum and glucocorticoid-regulated kinase 1 expression could be a marker for the rapid progression toward chronic kidney disease and a potential therapeutic target to slow down the process.

One size does not fit all: understanding individual living kidney donor risk

Living donor kidney transplantation is the optimal treatment for end-stage kidney disease (ESKD) but confers a risk upon the donor, both in the short term and many years after donation. While perioperative mortality is low and longevity does not appear to be adversely affected, there are small increases in the risk of other important morbidities. The overall risk of ESKD among donors is low but appears to be three- to five-fold higher than among healthy non-donors, and this relative risk is even higher among donors of African ancestry. For these individuals, apolipoprotein L1 genotyping may be helpful. Kidney donors also have an increased risk of developing hypertension post-donation and a modestly increased risk of developing gout. Living kidney donation also increases the risk of gestational hypertension and preeclampsia while not affecting other important pregnancy outcomes. As our understanding of donor risk grows, it is important to counsel prospective donors according to their individual risk and so obtain better informed donor consent. As knowledge advances, it is also important that all clinicians who manage kidney transplant candidates have an up to date understanding of donor risk to inform shared decision making.

Kidney Microstructural Features at the Time of Donation Predict Long-term Risk of Chronic Kidney Disease in Living Kidney Donors

OBJECTIVE

To determine whether microstructural features on a kidney biopsy specimen obtained during kidney transplant surgery predict long-term risk of chronic kidney disease in the donor.

PATIENTS AND METHODS

We studied kidney donors from May 1, 1999, through December 31, 2018, with a follow-up survey for the results of recent blood pressure and kidney function tests (estimated glomerular filtration rate [eGFR] and proteinuria). If not recently available, blood pressure and eGFRs were requested from a local clinic. Microstructural features on kidney biopsy at the time of donation were assessed as predictors of hypertension and kidney function after adjusting for years of follow-up, baseline age, sex, and clinical predictors.

RESULTS

There were 807 donors surveyed a mean 10.5 years after donation. An eGFR less than 45 mL/min/1.73 m2 in 6.4% (43/673) of donors was predicted by larger glomerular volume per standard deviation (odds ratio [OR], 1.48; 95% CI, 1.08 to 2.04) and nephron number below the age-specific 5th percentile (OR, 3.38; 95% CI, 1.31 to 8.72). An eGFR less than 60 mL/min/1.73 m2 in 42.5% (286/673) of donors was not predicted by any microstructural feature. Residual eGFR (postdonation/predonation eGFR) was predicted by nephron number below the age-specific 5th percentile (difference, -6.07%; 95% CI, -10.24% to -1.89%). Self-reported proteinuria in 5.1% (40/786) of donors was predicted by larger glomerular volume (OR, 1.42; 95% CI, 1.08 to 1.86). Incident hypertension in 18.8% (119/633) of donors was not predicted by any microstructural features.

CONCLUSION

Low nephron number for age and larger glomeruli are important microstructural predictors for long-term risk of chronic kidney disease after living kidney donation.

Hypertension, cardiovascular disease and cause of death in Danish living kidney donors: matched cohort study

OBJECTIVES

We aimed to investigate the long-term absolute risk of hypertension and cardiovascular disease after kidney donation in living kidney donors.

DESIGN

Living kidney donors were matched to 10 controls from the general population.

SETTING

Multiple Danish national registries were used to identify living kidney donors from 1 January 1996 to 31 December 2017 nationwide.

PARTICIPANTS

1262 living kidney donors and 12 620 controls.

MAIN OUTCOME MEASURES

Hypertension, cardiovascular disease and diabetes.

RESULTS

The median age of living kidney donors was 52 (men 43%). Hypertension developed in 50 (4%) and 231 (1.8%) with a median follow-up of 7 years (IQR 3.3-12.1 years with a maximum follow-up of 22 years) and 6.9 years (IQR 3.2-11.7 years and maximum follow-up of 22 years) for donors and controls, respectively. The absolute risk of hypertension was 2.3% (95% CI 1.4% to 3.2%) and 1.2% (95% CI 1.0% to 1.4%), 4.2% (95% CI 2.8% to 5.7%) and 2.4% (95% CI 2.1% to 2.8%), 8.6% (95% CI 6.0% to 11.3%) and 3.3% (95% CI 2.8% to 3.8%) within 5, 10, 15 years for donors and controls, respectively. The ratio of the 10-year absolute risks for hypertension was 1.64 (95% CI 1.44 to 1.88) for donors compared with the controls. Two donors and four controls developed renal replacement therapy requiring end-stage renal disease during follow-up. The absolute risk of cardiovascular disease and diabetes was 7.3% (95% CI 5.7% to 9.5%) and 8.3% (95% CI 7.7% to 9.0%), 1.7% (95% CI 0.7% to 2.8%) and 3.2% (95% CI 2.7% to 3.6%) at 10 years for donors and controls, respectively.

CONCLUSIONS

Living kidney donors have an increased long-term absolute risk of hypertension compared with controls from the general population.

Use of Dietary Supplements in Living Kidney Donors: A Critical Review

Dietary supplement use is high among US adults, with the intention by users to promote overall health and wellness. Kidney donors, who are selected based on their overall good health and wellness, can have high utilization rates of dietary supplements. We provide a framework for the evaluation of living kidney donors and use of dietary supplements. In this review, dietary supplements will include any orally administered dietary or complementary nutritional products, but excluding micronutrients (vitamins and minerals), food, and cannabis. Use of dietary supplements can influence metabolic parameters that mask future risk for chronic illness such as diabetes and hypertension. Dietary supplements can also alter bleeding risk, anesthesia and analgesic efficacy, and safety in a perioperative period. Finally, postdonation monitoring of kidney function and risk for supplement-related nephrotoxicity should be part of a kidney donor educational process. For practitioners evaluating a potential kidney donor, we provide a list of the most commonly used herbal supplements and the effects on evaluation in a predonation, perioperative donation, and postoperative donation phase. Finally, we provide recommendations for best practices for integration into a comprehensive care plan for kidney donors during all stages of evaluation. We recommend avoidance of dietary supplements in a kidney donor population, although there is a paucity of data that identifies true harm. Rather, associations, known mechanisms of action, and common sense suggest that we avoid use in this population.

Postdonation eGFR and New-Onset Antihypertensive Medication Use After Living Kidney Donation

Background.

Limited data are available regarding clinical implications of lower renal function after living kidney donation. We examined a novel integrated database to study associations between postdonation estimated glomerular filtration rate (eGFR) and use of antihypertensive medication (AHM) treatment after living kidney donation.

Methods.

Study data were assembled by linking national U.S. transplant registry identifiers, serum creatinine (SCr) values from electronic medical records, and pharmacy fill records for 3222 living donors (1989–2016) without predonation hypertension. Estimated GFR (mL/min per 1.73 m²) was computed from SCr values by the CKD-EPI equation. Repeated measures multivariable mixed effects modeling examined the associations (adjusted odds ratio, _95%LCLaOR_{95% UCL}) between AHM use and postdonation eGFR levels (random effect) with fixed effects for baseline donor factors.

Results.

The linked database identified an average of 3 postdonation SCr values per donor (range: 1–38). Lower postdonation eGFR (vs ≥75) bore graded associations with higher odds of AHM use (eGFR 30–44: aOR _0.951.47_2.26; <30: aOR _1.082.52_5.90). Other independent correlates of postdonation AHM use included older age at donation (aOR per decade: _1.081.23_1.40), black race (aOR _1.031.51_2.21), body mass index > 30 kg/m² (aOR _1.011.45_2.09), first-degree donor–recipient relationship (aOR _1.071.38_1.79), “prehypertension” at donation (systolic blood pressure 120–139: aOR _1.101.46_1.94; diastolic blood pressure 80–89: aOR _1.061.45_1.99).

Conclusions.

This novel linkage illustrates the ability to identify postdonation kidney function and associate it with clinically meaningful outcomes; lower eGFR after living kidney donation is a correlate of AHM treatment requirements. Further work should define relationships of postdonation renal function, hypertension, and other morbidity measures.

In sickness and in health: Living HIV positive kidney donation from a wife to her husband, with 7 years' post-transplant follow-up

Human immunodeficiency virus (HIV) infection was traditionally considered an absolute contraindication for kidney transplantation. After the introduction of ART, several studies have demonstrated comparable patient and graft outcomes between HIV-negative and HIV-positive kidney recipients. The US Congress passed the HIV Organ Policy Equity (HOPE) Act in 2013, which permits research in the area of HIV-positive to HIV-positive transplantation. HIV-infected living donation is also permitted under the HOPE Act. However, there is a concern regarding the safety of kidney donation in an HIV-infected person, given the risk of renal disease associated with HIV infection. We report here the case of successful kidney transplantation from HIV-positive living donor to HIV-positive recipient performed in our center on July 2012. To the best of our knowledge, this is the earliest case done in this medical context to be reported in the literature, therefore, potentially carrying several important messages to the transplantation community. In the present case, the living-donor kidney transplant was performed between a married couple infected with same strain of HIV-1, both on effective ART with efficiently suppressed viral replication and satisfactory pre-transplantation immune status.

Larger nephron size, low nephron number, and nephrosclerosis on biopsy as predictors of kidney function after donating a kidney

It is unclear whether structural findings in the kidneys of living kidney donors predict postdonation kidney function. We studied living kidney donors who had a kidney biopsy during donation. Nephron size was measured by glomerular volume, cortex volume per glomerulus, and mean cross-sectional tubular area. Age-specific thresholds were defined for low nephron number (calculated from CT and biopsy measures) and nephrosclerosis (global glomerulosclerosis, interstitial fibrosis/tubular atrophy, and arteriosclerosis). These structural measures were assessed as predictors of postdonation measured GFR, 24-hour urine albumin, and hypertension. Analyses were adjusted for baseline age, gender, body mass index, systolic and diastolic blood pressure, hypertension, measured GFR, urine albumin, living related donor status, and time since donation. Of 2673 donors, 1334 returned for a follow-up visit at a median 4.4 months after donation, with measured GFR <60 mL/min/1.73 m² in 34%, urine albumin >5 mg/24 h in 13%, and hypertension in 5.3%. Larger glomerular volume and interstitial fibrosis/tubular atrophy predicted follow-up measured GFR <60 mL/min/1.73 m² . Larger cortex volume per glomerulus and low nephron number predicted follow-up urine albumin >5 mg/24 h. Arteriosclerosis predicted hypertension. Microstructural findings predict GFR <60 mL/min/1.73 m² , modest increases in urine albumin, and hypertension shortly after kidney donation.

Maternal and fetal outcomes of pregnancies in kidney donors: A 30-year comparative analysis of matched non-donors in a single center

Background

Woman kidney donors face obstetric complication risks after kidney donation, such as gestational hypertension and preeclampsia. Studies on childbirth-related complications among Asian women donors are scarce.

Methods

This retrospective cohort study included woman donors aged 45 years or younger at the time of kidney donation in a single tertiary hospital between 1985 and 2014. Pregnancy associated complications were investigated using medical records and telephone questionnaires for 426 pregnancies among 225 donors. Matched non-donor controls were selected by propensity score and the maternal and fetal outcomes were compared with those of donors. Primary outcomes were differences in maternal complications, and secondary outcomes were fetal outcomes in pregnancies of the donor and control groups.

Results

A total of 56 cases had post-donation pregnancies. The post-donation pregnancies group was younger at the time of donation and older at the time of delivery than the pre-donation pregnancies group, and there were no differences in primary outcomes between the groups except the proportion receiving cesarean section. Comparison of the complication risk between post-donation pregnancies and non-donor matched controls showed no significant differences in gestational hypertension, preeclampsia, or composite outcomes after propensity score matching including age at delivery, era at pregnancy, systolic blood pressure, body weight, and estimated glomerular filtration ratio (odds ratio, 0.63; 95% confidence interval, 0.19–2.14; P = 0.724).

Conclusion

This study revealed that maternal and fetal outcomes between woman kidney donors and non-donor matched controls were comparable. Studies with general population pregnancy controls are warranted to compare pregnancy outcomes for donors.

Implications of excess weight on kidney donation: Long-term consequences of donor nephrectomy in obese donors

BACKGROUND

An elevated body mass index (>30 kg/m²) has been a relative contraindication for living kidney donation; however, such donors have become more common. Given the association between obesity and development of diabetes, hypertension, and end-stage renal disease, there is concern about the long-term health of obese donors.

METHODS

Donor and recipient demographics, intraoperative parameters, complications, and short- and long-term outcomes were compared between contemporaneous donors-obese donors (body mass index ≥30 kg/m²) versus nonobese donors (body mass index <30 kg/m²).

RESULTS

Between the years 1975 and 2014, we performed 3,752 donor nephrectomies; 656 (17.5%) were obese donors. On univariate analysis, obese donors were more likely to be older (P < .01) and African American (P < .01) and were less likely to be a smoker at the time of donation (P = .01). Estimated glomerular filtration rate at donation was higher in obese donors (115 ± 36 mL/min/1.73m²) versus nonobese donors (97 ± 22 mL/min/1.73m²; P < .001). There was no difference between groups in intraoperative and postoperative complications; but intraoperative time was longer for obese donors (adjusted P < .001). Adjusted postoperative length of stay (LOS) was longer (adjusted P = .01), but after adjustment for donation year, incision type, age, sex, and race, there were no differences in short-term (<30 days) and long-term (>30 days) readmissions. Estimated glomerular filtration rate and rates of end-stage renal disease were not significantly different between donor groups >20 years after donation (P = .71). However, long-term development of diabetes mellitus (adjusted hazard ratio (HR) 3.14; P < .001) and hypertension (adjusted hazard ratio (HR) 1.75; P < .001) was greater among obese donors and both occurred earlier (diabetes mellitus: 12 vs 18 years postnephrectomy; hypertension: 11 vs 15 years).

CONCLUSION

Obese donors develop diabetes mellitus and hypertension more frequently and earlier than nonobese donors after donation, raising concerns about increased rates of end-stage renal disease.