Long-term follow-up of kidney donors: a longitudinal study

The Minnesota attributable risk of kidney donation (MARKD) study: a retrospective cohort study of long-term (> 50 year) outcomes after kidney donation compared to well-matched healthy controls

BACKGROUND

There is uncertainty about the long-term risks of living kidney donation. Well-designed studies with controls well-matched on risk factors for kidney disease are needed to understand the attributable risks of kidney donation.

METHODS

The goal of the Minnesota Attributable Risk of Kidney Donation (MARKD) study is to compare the long-term (> 50 years) outcomes of living donors (LDs) to contemporary and geographically similar controls that are well-matched on health status. University of Minnesota (n = 4022; 1st transplant: 1963) and Mayo Clinic LDs (n = 3035; 1st transplant: 1963) will be matched to Rochester Epidemiology Project (REP) controls (approximately 4 controls to 1 donor) on the basis of age, sex, and race/ethnicity. The REP controls are a well-defined population, with detailed medical record data linked between all providers in Olmsted and surrounding counties, that come from the same geographic region and era (early 1960s to present) as the donors. Controls will be carefully selected to have health status acceptable for donation on the index date (date their matched donor donated). Further refinement of the control group will include confirmed kidney health (e.g., normal serum creatinine and/or no proteinuria) and matching (on index date) of body mass index, smoking history, family history of chronic kidney disease, and blood pressure. Outcomes will be ascertained from national registries (National Death Index and United States Renal Data System) and a new survey administered to both donors and controls; the data will be supplemented by prior surveys and medical record review of donors and REP controls. The outcomes to be compared are all-cause mortality, end-stage kidney disease, cardiovascular disease and mortality, estimated glomerular filtration rate (eGFR) trajectory and chronic kidney disease, pregnancy risks, and development of diseases that frequently lead to chronic kidney disease (e.g. hypertension, diabetes, and obesity). We will additionally evaluate whether the risk of donation differs based on baseline characteristics.

DISCUSSION

Our study will provide a comprehensive assessment of long-term living donor risk to inform candidate living donors, and to inform the follow-up and care of current living donors.

Prevalence, Mechanisms, Treatment, and Complications of Hypertension Postliving Kidney Donation

Living kidney donors represent a unique population of patients. Potential donors are selected based on the belief that their preoperative fitness is likely to mitigate the risks of long- and short-term harm following uninephrectomy. Studies performed on postdonation outcomes have largely focused on mortality and the risk of end-stage renal failure, but have also investigated secondary outcomes such as cardiovascular morbidity and hypertension. It has been postulated that hypertension is a possible outcome of living kidney donation. A variety of studies have been conducted to investigate the prevalence, epidemiology, mechanisms, treatment strategies, and long-term ramifications of hypertension postdonation. These studies are heterogeneous in their population, design, methodology, and outcome measures and have presented contradicting outcomes. Additionally, the absence of a well-matched control group has made it challenging to interpret and generalise the reported findings. As such, it is not possible to definitively conclude that hypertension occurs at a higher rate among donors than the general population. This article will review the evidence of postdonation hypertension prevalence, mechanisms, treatment, and complications.

Long-Term Outcome of Live Kidney Donation in South Korea

Background

Kidney donors may be at increased risk for end-stage renal disease (ESRD) as well as cardiovascular and all-cause mortality. In particular, data on long-term safety after kidney donation in Asian populations are lacking. We aimed to assess the safety of live kidney donation in Korean donors by using a matched control group.

Material/Methods

We conducted a retrospective cohort study using a hospital-based database (Asan Medical Center, Seoul, Korea) and a control group from the national health insurance claims database in South Korea. We analyzed the health status of 1608 kidney donors who underwent donation between September 1990 and December 2015, and we compared their characteristics with those of matched 6426 non-donors (1: 4 ratio). We also measured the glomerular filtration rate (GFR) with ⁵¹Cr EDTA and urinary albumin excretion and assessed the prevalence of hypertension, diabetes, and general health status in 200 volunteer donors.

Results

Mortality was significantly lower in kidney donors compared with the matched controls (130.2 vs. 185.4 per 100,000 person-years, P=0.02). There was no significant difference in mortality if a donor had hypertension or was a current smoker at the time of donation. There was also no significant difference in ESRD (43.1 vs. 35.2 per 100,000 person-years, P=0.07) between the 2 groups regardless of hypertension and smoking status. Among the 200 donors with measured GFR, 11.5% had GFR values <60 ml/min/1.73 m² at 9.4±5.3 years after donation. Older age (P=0.001) and female sex (P=0.021) were significantly associated with GFR values <60 mL/min/1.73 m².

Conclusions

Mortality and ESRD were uncommon in carefully selected kidney donors. However, donors with pre-existing risk factors should be followed up more closely to ensure long-term safety.

Prevalence and risk factors of hypertension following nephrectomy in living kidney donors

Living donor kidney transplantation is the treatment of choice for the patients with end-stage renal disease, especially where deceased donor programs are limited. There are limited data on the outcomes of living kidney donors (LKD) from developing countries, especially from North Africa. The aim of this study is to evaluate the prevalence of hypertension (HTN) in LKD and to analyze its risk factors. This is a longitudinal monocentric study, and the donors who underwent nephrectomy for donation between 2006 and 2015 were included. Ninety-two donors were assessed. The mean age at the time of nephrectomy was 42.8 ± 10 years (21-68 years). The sex ratio was 0.6. At the time of donation, the median systolic blood pressure was 120 mm Hg and the median diastolic blood pressure was 70 mm Hg. HTN was noted in 4% of donors. The median follow-up duration was 26 months. Two years after donation, the prevalence of HTN was 28% in the study group (8% male and 20% female). The mean time to development of HTN was 16 months. Associations between HTN after donation and the cardiovascular family history, age >40 years, HTN, obesity, android obesity, glomerular filtration rate GFR <90 mL/min/1.73 m², perioperative HTN, and dyslipidemia were noted. The multivariate analysis showed that obesity at the time of donation was a risk factor for HTN (odds ratio = 4.8; P = 0.04). Obese donor [body mass index (BMI) ≥30)] has higher risk of HTN after nephrectomy than nonobese donor.

Evaluation of Preoperative Abdominal Adipose Tissue-, Inflammation-, Muscle Mass-, and Nutritional Status-based Prognostic Markers to Assess Renal Dysfunction in Living Kidney Donors

BACKGROUND

Living kidney donors (LKDs) are at high risk of renal dysfunction after undergoing a donor nephrectomy (DN), resulting in poor prognosis associated with the development of cardiovascular or cerebrovascular disease. Decreasing this risk can improve the survival rate of LKDs. We investigated the effects of preoperative conditions in LKDs on renal dysfunction after DN using abdominal adipose tissue, inflammation, nutritional status, and muscle mass as markers for this assessment.

METHODS

Our retrospective study included 79 LKDs. Body composition markers were assessed using preoperative unenhanced computed tomographic images. Inflammation- and nutritional status-based markers were assessed using preoperative laboratory blood tests. The association between each marker was investigated, and prognostic markers for renal dysfunction after DN were identified.

RESULTS

The LKDs in this cohort comprised 30 men and 49 women. The median age at the time of DN and the preoperative estimated glomerular filtration rate were 58 years and 81.9 mL/min/1.73 m², respectively. Abdominal subcutaneous adipose tissue and muscle mass significantly differed between the sexes. Each adipose tissue-, inflammation-, nutritional status-, and muscle mass-based marker showed an association with each other. Abdominal visceral adipose tissue and nutritional status could be independent prognostic markers for renal dysfunction after DN.

CONCLUSIONS

Our findings suggest that the preoperative condition of LKDs (assessed using specific markers such as abdominal visceral adipose tissue mass per volume and nutritional status) could affect renal dysfunction after DN. Optimal preoperative management can lead to better outcomes in LKDs. Further research is needed to establish appropriate exercise programs and nutritional interventions.

Solitary kidney and risk of chronic kidney disease

The renal outcome of solitary kidney remains controversial. We examined the longitudinal association of congenital or acquired solitary kidney with the development of chronic kidney disease (CKD). A cohort study was performed involving 271,171 Korean men and women free of CKD at baseline who underwent a health screening program and who were followed annually or biennially for an average of 5.4 years. Solitary kidney was determined based on ultrasonographic findings. CKD was defined as an estimated glomerular filtration rate of < 60 ml/min/1.73 m² and/or the presence of proteinuria in two or more consecutive visits. During 1,472,519.6 person-years of follow-up, 2989 participants developed CKD (incidence rate: 2.0 per 1000 person-years). After adjustment for potential confounders, the aHR (95% CIs) for incident CKD comparing solitary kidney to the control was 3.26 (1.63-6.54). In analyses of cause-specific solitary kidney, aHR (95% CIs) for CKD comparing unilateral nephrectomy and congenital solitary kidney to the control were 6.18 (2.31-16.49) and 2.22 (0.83-5.92), respectively. The association between solitary kidney and CKD was stronger in men. Having a solitary kidney was independently associated with an increased risk of CKD development. Therefore, preventive strategies for reducing the risk of CKD are required in individuals with a solitary kidney.

Measured Glomerular Filtration Rate After Kidney Donation: No Evidence of Accelerated Decay

BACKGROUND

The rate of measured glomerular filtration rate (GFR) change in kidney donor years after donation has not been adequately addressed. Whether this change is accelerated in the setting of 1 kidney is also understudied.

METHODS

Two hundred fourteen randomly selected donors underwent serial GFR measurements of nonradioactive iohexol. Estimated GFR at each visit was calculated using the Chronic Kidney Disease Epidemiology Collaboration and Modification of Diet in Renal Disease study equations.

RESULTS

Glomerular filtration rate visits were 4.8 ± 1.3 years apart and the second occurring 16.9 ± 9.1 years after donation. Most (97.7%) were white, 60.8% female, and 78.5% were related to their recipient. Most, 84.6%, had a GFR of 60 mL/min per 1.73 m or higher, 14.0% had a GFR between 45 and 60 mL/min per 1.73 m, and 1.4% had a GFR less than 45 mL/min per 1.73 m. Between visits 1 and 2, 56.5% had a GFR decline, 36.0% increase, and in 7.5%, there was no change. Overall, GFR declined at a rate of -0.42 mL/min per 1.73 m per year. Of GFR estimating models, only Chronic Kidney Disease Epidemiology Collaboration-Creatinine equation produced a slope that was steeper than measured GFR.

CONCLUSIONS

Nearly 2 decades postdonation GFR declined at a rate similar to that seen in the general population, and in one third, GFR continues to increase.

Impact of Preoperative Abdominal Visceral Adipose Tissue Area and Nutritional Status on Renal Function After Donor Nephrectomy in Japanese Living Donors for Renal Transplantation

BACKGROUND Living kidney donors face the risk of renal dysfunction, resulting in end-stage renal disease, cardiovascular disease, or cerebrovascular disease, after donor nephrectomy. Reducing this risk is important to increasing survival of living donors. In this study, we investigated the effect of preoperative distribution of abdominal adipose tissue and nutritional status on postoperative renal function in living donors. MATERIAL AND METHODS Seventy-five living donors were enrolled in this retrospective study. Preoperative unenhanced computed tomography images were used to measure abdominal adipose tissue parameters. Prognostic nutritional index (PNI) was used to assess preoperative nutritional status. Donors were divided into 2 groups according to abdominal visceral adipose tissue (VAT) area at the level of the fourth and fifth lumbar vertebrae (<80 or ≥80 cm²). Postoperative renal function was compared in the 2 groups, and prognostic factors for development of chronic kidney disease (CKD) G3b were identified using multivariate analysis. RESULTS Donors with a VAT area ≥80 significantly more often had hypertension preoperatively. Although there was no significant difference in preoperative estimated glomerular filtration rate (eGFR) between the 2 groups, postoperative renal function was significantly decreased in donors with a VAT area ≥80 compared to those with a VAT area <80. In multivariate analysis, VAT area ≥80 and PNI <54 were independent factors predicting the development of CKD G3b after 12 months. CONCLUSIONS Our findings suggest that preoperative VAT and PNI affect postoperative renal function. Further research is required to establish appropriate exercise protocols and nutritional interventions during follow-up to improve outcomes in living donors.

Causes and timing of end-stage renal disease after living kidney donation

End-stage renal disease (ESRD) is a risk after kidney donation. We sought, in a large cohort of kidney donors, to determine the causes of donor ESRD, the interval from donation to ESRD, the role of the donor/recipient relationship, and the trajectory of the estimated GFR (eGFR) from donation to ESRD. From 1/1/1963 thru 12/31/2015, 4030 individuals underwent living donor nephrectomy at our center, as well as ascertainment of ESRD status. Of these, 39 developed ESRD (mean age ± standard deviation [SD] at ESRD, 62.4 ± 14.1 years; mean interval between donation and ESRD, 27.1 ± 9.8 years). Donors developing ESRD were more likely to be male, as well as smokers, and younger at donation, and to have donated to a first-degree relative. Of donors with a known cause of ESRD (n = 25), 48% was due to diabetes and/or hypertension; only 2 from a disease that would have affected 1 kidney (cancer). Of those 25 with an ascertainable ESRD cause, 4 shared a similar etiology of ESRD with their recipient. Almost universally, thechange of eGFR over time was stable, until new-onset disease (kidney or systemic). Knowledge of factors contributing to ESRD after living kidney donation can improve donor selection and counseling, as well as long-term postdonation care.

GFR ≤25 years postdonation in living kidney donors with (vs. without) a first-degree relative with ESRD

An increased risk of ESRD has been reported for living kidney donors, and appears to be higher for those donating to a relative. The reasons for this are not clear. One possibility is that ESRD is due to the nephrectomy-related reduction in GFR, followed by an age-related decline that may be more rapid in related donors. Between 1/1/1990 and 12/31/2014, we did 2002 living donor nephrectomies. We compared long-term postdonation eGFR trajectory for donors with (n = 1245) vs. without (n = 757) a first-degree relative with ESRD. Linear mixed-effects models were used to model the longitudinal trajectory of eGFR. With all other variables held constant, we noted a steady average increase in eGFR until donors reached age 70: 1.12 (95% CI: 0.92-1.32) mL/min/1.73m^² /yr between 6 weeks and 5 years postdonation; 0.24 (0.00-0.49) mL/min/1.73m^² /yr between 5 and 10 years; and 0.07 (-0.10 to +0.25) mL/min/1.73m^² /yr between 10 and 20 years for donors with attained age less than 70. After age 70, eGFR declined. After we adjusted for predonation factors, the difference in eGFR slopes between related and unrelated donors was 0.20 mL/min/1.753 m² /year (0.07-0.33). Our data suggests that postdonation, kidney donor eGFR increases each year for a number of years and that eGFR trajectory does not explain any increase in ESRD after donation.

Simulating a virtual population's sensitivity to salt and uninephrectomy

Salt sensitivity, with or without concomitant hypertension, is associated with increased mortality. Reduced functional renal mass plays an important role in causing salt-sensitive hypertension for many individuals. Factors that are important in the condition of decreased renal mass and how they affect blood pressure (BP) or salt sensitivity are unclear. We used HumMod, an integrative mathematical model of human physiology, to create a heterogeneous population of 1000 virtual patients by randomly varying physiological parameters. We examined potential physiological mechanisms responsible for the change in BP in response to high-salt diet (8× change in salt intake for three weeks) with full kidney mass and again after the removal of one kidney in the same group of virtual patients. We used topological data analysis (TDA), a clustering algorithm tool, to analyse the large dataset and separate patient subpopulations. TDA distinguished five unique clusters of salt-sensitive individuals (more than 15 mmHg change in BP with increased salt). While these clusters had similar BP responses to salt, different collections of variables were responsible for their salt sensitivity, e.g. greater reductions in glomerular filtration rate (GFR) or impairments in the renin-angiotensin system. After simulating uninephrectomy in these virtual patients, the three most salt-sensitive clusters were associated with a blunted increase in renal blood flow (RBF) and higher increase in loop and distal sodium reabsorption when compared with the salt-resistant population. These data suggest that the suppression of sodium reabsorption and renin-angiotensin system is key for salt resistance, and RBF in addition to GFR may be an important factor when considering criteria for kidney donors. Here, we show that in our model of human physiology, different derangements result in the same phenotype. While these concepts are known in the experimental community, they were derived here by considering only the data obtained from our virtual experiments. These methodologies could potentially be used to discover patterns in patient sensitivity to dietary change or interventions and could be a revolutionary tool in personalizing medicine.

Donation, Not Disease! A Multiple-Hit Hypothesis on Development of Post-Donation Kidney Disease

Purpose of Review

The risks following living kidney donation has been the subject of rigorous investigation in the past several decades. How to utilize the burgeoning new knowledge base to better the risk assessment, education, and health maintenance of donors is unclear. We review the physiologic and epidemiologic evidences on the post-donation state and submit a multiple-hit hypothesis to reconcile the finite elevation in risk of kidney disease after donation with the benign course of most kidney donors.

Recent Findings

The risk of end-stage kidney disease is higher in kidney donors compared to similarly healthy non-kidney donors. Nonetheless, post-donation kidney disease is uncommon and arises mostly in the setting of other “hits”—either a “first hit” present at birth or a “second hit” acquired later in life.

Summary

The transplant community’s focus should be directed toward (1) personalized risk assessment to inform consent before donation and (2) preventing and treating development of “second hits” following kidney donation.

The National Landscape of Living Kidney Donor Follow-Up in the United States

In 2013, the Organ Procurement and Transplantation Network (OPTN)/ United Network for Organ Sharing (UNOS) mandated that transplant centers collect data on living kidney donors (LKDs) at 6 months, 1 year, and 2 years postdonation, with policy-defined thresholds for the proportion of complete living donor follow-up (LDF) data submitted in a timely manner (60 days before or after the expected visit date). While mandated, it was unclear how centers across the country would perform in meeting thresholds, given potential donor and center-level challenges of LDF. To better understand the impact of this policy, we studied Scientific Registry of Transplant Recipients data for 31,615 LKDs between January 2010 and June 2015, comparing proportions of complete and timely LDF form submissions before and after policy implementation. We also used multilevel logistic regression to assess donor- and center-level characteristics associated with complete and timely LDF submissions. Complete and timely 2-year LDF increased from 33% prepolicy (January 2010 through January 2013) to 54% postpolicy (February 2013 through June 2015) (p < 0.001). In an adjusted model, the odds of 2-year LDF increased by 22% per year prepolicy (p < 0.001) and 23% per year postpolicy (p < 0.001). Despite these annual increases in LDF, only 43% (87/202) of centers met the OPTN/UNOS-required 6-month, 1-year, and 2-year LDF thresholds for LKDs who donated in 2013. These findings motivate further evaluation of LDF barriers and the optimal approaches to capturing outcomes after living donation.

Risk-Factor Profile of Living Kidney Donors: The Australia and New Zealand Dialysis and Transplant Living Kidney Donor Registry 2004-2012

BACKGROUND

Recent literature suggests that living kidney donation may be associated with an excess risk of end-stage kidney disease and death. Efforts to maximize access to transplantation may result in acceptance of donors who do not fit within current guidelines, potentially placing them at risk of adverse long-term outcomes.

METHODS

We studied the risk profile of Australian and New Zealand living kidney donors using data from the Australia and New Zealand Dialysis and Transplant Living Kidney Donor Registry over 2004 to 2012. We compared their predonation profile against national guidelines for donor acceptance.

RESULTS

The analysis included 2,932 donors (mean age 48.8 ± 11.2 years, range 18-81), 58% female and 87% Caucasian. Forty (1%) had measured glomerular filtration rate less than 80 mL/min; 32 (1%) had proteinuria >300 mg/day; 589 (20%) were hypertensive; 495 (18%) obese; 9 (0.3%) were diabetic while a further 55 (2%) had impaired glucose tolerance; and 218 (7%) were current smokers. Overall 767 donors (26%) had at least one relative contraindication to donation and 268 (9%) had at least one absolute contraindication according to national guidelines.

CONCLUSIONS

Divergence of current clinical practice from national guidelines has occurred. In the context of recent evidence demonstrating elevated long-term donor risk, rigorous follow-up and reporting of outcomes are now mandated to ensure safety and document any change in risk associated with such a divergence.

Ultrastructural changes and nestin expression accompanying compensatory renal growth after unilateral nephrectomy in adult rats

Background

Several renal disorders affect the glomerular podocytes. Compensatory structural and functional changes have been observed in animals that have undergone unilateral renal ablation. These changes occur as a pliant response to quench the increased functional demand to maintain homeostasis of fluid and solutes. Nestin is an intermediate filament protein present in the glomerular podocytes of the adult kidney and is linked with the maintenance of its foot process structure. Structural changes in the podocytes ultimately restructure the filtration barrier. Very few studies related to the ultrastructural and histopathologic changes of the podocytes are documented. The present study aimed to assess the histopathologic changes at the ultrastructural level in the adapted kidney at different time intervals following unilateral renal ablation in adult rats and its relation with nestin.

Methods

Forty-eight rats were divided into four groups (n=12 in each group). The animals of Group A were control naïve rats, while the group B, group C and group D animals underwent left unilateral nephrectomy and the remaining right kidney was removed on days 10, 20 and 30, respectively. Each group included four sham-operated rats, which were sacrificed at the same time as the naïve rats. Each nephrectomized sample was weighed and its sections were subjected to hematoxylin and eosin examination, transmission electron microscopic study as well as immunostaining using the intermediate filament protein nestin.

Results

No difference was found between the kidney sections from the control group and the sham-operated groups. A significant increase in the weight of the right kidneys was noted in groups B, C and D (P<0.001). The ultrastructural adaptive changes seen in the glomeruli of group B were subsequently reduced in groups C and D. This finding corresponded to a similar pattern of nestin expression in the podocytes, which showed significant increase in group B followed by reduced expression in groups C and D. Histopathologic and transmission electron microscopic evaluation of group B showed signs of kidney injury. On the other hand, group C animals showed markedly reduced renal adaptive changes and similar changes were also noted in group D.

Conclusion

Correlation between nestin expression and the ultrastructural changes confirms that nestin has a role in increasing the mechanical stability of the podocytes in order to enhance their morphologic changes in response to the tensile glomerular capillary wall. However, further studies investigating more remote ultrastructural changes and their relation with nestin expression are needed to confirm this relationship.

Cystatin-C is associated with partial recovery of kidney function and progression to chronic kidney disease in living kidney donors: Observational study

Donor nephrectomy in living-donor kidney transplantation may result in hyperfiltration injury in remnant kidney; however, its clinical implication in partial recovery of kidney function (PRKF) in remnant kidney and chronic kidney disease (CKD) progression remains unclear. Thus, we investigated the effect of PRKF on CKD development in the residual kidney and the utility of cystatin-C (Cys-C) in evaluating renal function in living-donor kidney transplantation donors.The electronic medical records and laboratory results of 1648 kidney transplant (KT) donors and 13,834 healthy nondonors between January 2006 and November 2014 were reviewed. The predictors of PRKF and CKD diagnosed by Kidney Disease: Improving Global Outcomes (KDIGO) criteria were evaluated by multivariate analysis. CKD risk was compared between KT donors and healthy nondonors using Cox proportional hazard regression analysis following propensity score matching (PSM).The incidence of PRKF for KT donors was 49.3% (813). CKD incidence was 24.8% (408) in KT donors and 2.0% (277) in healthy nondonors. The predictors of PRKF were, male sex (odds ratio [OR], 17.32; 95% confidence interval [CI] 9.16-32.77), age (OR, 1.02; 95% CI, 1.00-1.04; P < 0.001), Cys-C concentration (OR, 1.02; 95% CI, 1.00-1.04; P = 0.02), and preoperative albumin level (OR, 0.49; 95% CI, 0.27-0.89; P = 0.02). The predictors of CKD were age (hazards ratio [HR], 1.04; 95% CI, 1.02-1.05; P < 0.001), Cys-C concentration (HR, 1.024; 95% CI, 1.012-1.037; P < 0.001), and PRKF (HR, 1.41; 95% CI, 1.04-1.92; P = 0.03). After PSM, the risk of progression to CKD was higher in KT donors than in healthy nondonors (HR, 58.4; 95% CI, 34.2-99.8; P < 0.001).Donor nephrectomy is associated with PRKF and progression to CKD. Cys-C is a useful early marker for detecting PRKF and CKD.

Nephron number, hypertension, and CKD: physiological and genetic insight from humans and animal models

The kidneys play a vital role in the excretion of waste products and the regulation of electrolytes, maintenance of acid-base balance, regulation of blood pressure, and production of several hormones. Any alteration in the structure of the nephron (basic functional unit of the kidney) can have a major impact on the kidney's ability to work efficiently. Progressive decline in kidney function can lead to serious illness and ultimately death if not treated by dialysis or transplantation. While there have been numerous studies that implicate lower nephron numbers as being an important factor in influencing susceptibility to developing hypertension and chronic kidney disease, a direct association has been difficult to establish because of three main limitations: 1) the large variation in nephron number observed in the human population; 2) no established reliable noninvasive methods to determine nephron complement; and 3) to date, nephron measurements have been done after death, which doesn't adequately account for potential loss of nephrons with age or disease. In this review, we will provide an overview of kidney structure/function, discuss the current literature for both humans and other species linking nephron deficiency and cardio-renal complications, as well as describe the major molecular signaling factors involved in nephrogenesis that modulate variation in nephron number. As more detailed knowledge about the molecular determinants of nephron development and the role of nephron endowment in the cardio-renal system is obtained, it will hopefully provide clinicians the ability to accurately identify people at risk to develop CKD/hypertension and lead to a shift in patient care from disease treatment to prevention.

Living Donors' Perception of Their Quality of Health after Donation

To alleviate the long wait on the cadaveric transplant list, recipients are pursuing the option of living donation. Potential donors may have significant concerns about the decision to donate, including the quality of health after donation. This study identifies living donors' perception regarding their quality of health after donating a kidney, and identifies the perception of the adequacy of the medical follow-up after donation. In this retrospective study, the 36-Item Short Form Health Survey was mailed to all kidney donors at the transplant center from January 1995 to December 1998 (n = 118). The study population scored significantly better than the US sample population in all 8 categories of the questionnaire. When comparing scores using the relationship of the donor to the recipient, mean scores of donors who were “distant relatives” were found to be lower in 7 of the 8 categories. Most donors who had follow-up after donation felt it to be excellent to good; yet 50% stated they had no healthcare follow-up after donation. Themes were identified regarding the type of follow-up donors felt they needed after donation. Donors perceived their quality of health after donation as better than the general US population. Donor follow-up needs to be emphasized and followed more systematically.

Male Gender and Body Mass Index Are Associated With Hypertension and Reduced Kidney Function 5 or More Years After Living Kidney Donation

BACKGROUND

The objective of this study was to evaluate renal function and to explore the relationship between some risk factors in kidney donors 12.37 ± 7.60 years after donation.

PATIENTS AND METHODS

In a cross-sectional study conducted in a transplant unit, 77 nephrectomized subjects were assessed ≥5 years after donation to evaluate their renal function and the presence or absence of hypertension, dyslipidemia, and microalbuminuria.

RESULTS

Twenty donors had an estimated glomerular filtration rate of <60 mL/min/1.73 m(2). Nine donors showed urinary albumin excretion of >20 μg/min (11.68%). Subjects with an EGFR of <60 mL/min were predominantly male and hypertensive and showed higher body mass index (BMI), higher uric acid, higher total cholesterol/high-density lipoprotein cholesterol (TC/HDL-C), and logarithm of triglycerides/HDL-C (log TG/HDL-C) ratios than donors with an EGFR of >60 mL/min. Hypertensive donors were older and had higher BMI, higher UA serum values, higher TC/HDL-C and log TG/HDL-C ratios and microalbuminuria than nonhypertensive donors (P < .005). A multivariate analysis was conducted and, after final adjustment, a filtration rate of <60 mL/min was 3.05 times higher in men than women, increased 10% for each 1-unit increase in BMI and was positively associated with log (TG/HDL-C). The frequency of hypertension increased by 10% for each 1-unit increase in BMI and was positively associated with microalbuminuria.

CONCLUSION

In this sample of kidney donors from a single transplant unit, ≥5 years after donation, male sex and high BMI were positively associated with the presence of kidney failure.

Predictors of low estimated glomerular filtration rate after living kidney donation in a Southeast Asian population from Singapore

AIM

Post-donation kidney function has not been well characterized in the Southeast Asian population. We studied a retrospective cohort of 174 living kidney donors at Singapore General Hospital between 1976 and 2012, evaluated patterns of change in kidney function using quantile regression analysis and investigated for predictors of low estimated glomerular filtration rate (eGFR) < 60 mL/min per 1.73m² . Median follow-up time (range) was 7.8 (0.1-33.8) years following donor nephrectomy.

RESULTS

Of the donors, 43.1% regained 75% or more of pre-nephrectomy eGFR after 5 years post-donation; 9.8% exhibited 100% recovery to pre-nephrectomy eGFR. High pre-nephrectomy eGFR was protective for risk of low post-donation eGFR, with a 6% risk reduction for each unit increase in pre-nephrectomy eGFR (odds ratio, 0.94; 95% confidence interval, 0.91-0.97; P = 0.002). This relationship was stronger in the short term (>6 months to < 5 years) than medium to long term (5 years or longer) (interaction P = 0.052).

CONCLUSION

In general, kidney function is well preserved following kidney donation in Southeast Asian donors. Pre-nephrectomy eGFR is a good predictor of post-donation eGFR, especially in the short-term.

Living Kidney Donors Who Develop Kidney Failure: Excerpts of Their Thoughts

BACKGROUND

Psychosocial data about living kidney donors have been collected for almost 5 decades now. To date, however, no study has provided any psychosocial follow-up of donors who developed a serious health problem such as end-stage renal disease (ESRD).

METHODS

Donors who developed ESRD were invited to participate in a qualitative interview if they met one or both of the inclusion criteria: (1) developed ESRD within 10 years of donating and/or (2) lacked health insurance at the time of donation. We contacted 38 individuals who met these criteria, and 22 participated (58%). Two were subsequently excluded from analysis.

RESULTS

Twenty qualitative interviews were analyzed. Five findings are described: (1) donors describe the decision-making process as spontaneous and fast; (2) donors describe lack of appreciation for the need for post-donation self-care; (3) donors do not regret donating despite the adverse outcome; (4) donors advise future donors to have in place emotional and physical support post donation; and (5) donors appreciate the opportunity to tell their story from being a living donor to living with ESRD, which virtually all perceive as 2 separate unrelated events.

CONCLUSIONS

Most donors are positive about their donation decision and experience and would donate again, despite developing ESRD themselves. They propose some important changes to the decision-making and informed-consent processes. Our data are reassuring regarding lack of donor regret, but highlight the need for living donor transplant programs to ensure that living donors understand their long-term risks and receive appropriate life-long follow-up care to minimize these risks.

Deterioration in the renal function and risk of microalbuminuria after radical, simple and donor nephrectomy: A long-term outcome

Objectives:

Evaluation of deterioration in renal function and risk of micro albuminuria after radical, simple and donor nephrectomy.

Materials and Methods:

A total of 594 patients underwent nephrectomy (159 radical, 318 simple and 117 donors) from February 2009 to December 2012 in our institute. First 300 eligible patients were divided in 3 groups, each having equalled number of patients. Group 1 was consisted of patients who underwent radical, group 2 had simple and group 3 had donor nephrectomy. These patients were followed up to February 2015. Follow up of all the patients were done at first month following the surgery and then in every six months subsequently. The follow up included the measurement of serum creatinine and urinary micro albumin in a spot urine sample. CKD-EPI equation was used for calculation of e GFR.

Results:

At the end of our study, 35 patients (41.6%) in group 1 and 8 patients (8.69%) in group 2 developed CKD stage 3. During the follow-up period, 41% patients in group 1, 13% in group 2 and 4% in group 3 developed MA.

Conclusion:

Nephron-sparing surgery should be the standard treatment of renal tumors, wherever possible. There should be a regular follow up of the patients after radical, simple and donor nephrectomy because of risk of CKD. Early consultation with nephrologists should be done by the patients who are suffering from MA after nephrectomy.

LOng-term follow-up after liVE kidney donation (LOVE) study: a longitudinal comparison study protocol

Background

The benefits of live donor kidney transplantation must be balanced against the potential harm to the donor. Well-designed prospective studies are needed to study the long-term consequences of kidney donation.

Methods

The “LOng-term follow-up after liVE kidney donation” (LOVE) study is a single center longitudinal cohort study on long-term consequences after living kidney donation. We will study individuals who have donated a kidney from 1981 through 2010 in the Erasmus University Medical Center in Rotterdam, The Netherlands. In this time period, 1092 individuals donated a kidney and contact information is available for all individuals. Each participating donor will be matched (1:4) to non-donors derived from the population-based cohort studies of the Rotterdam Study and the Study of Health in Pomerania. Matching will be based on baseline age, gender, BMI, ethnicity, kidney function, blood pressure, pre-existing co-morbidity, smoking, the use of alcohol and highest education degree. Follow-up data is collected on kidney function, kidney-related comorbidity, mortality, quality of life and psychological outcomes in all participants.

Discussion

This study will provide evidence on the long-term consequences of live kidney donation for the donor compared to matched non-donors and evaluate the current donor eligibility criteria.

Trial registration

Dutch Trial Register NTR3795.

Renal cell carcinoma: risks and benefits of nephron-sparing surgery for T1 tumors

Renal cell carcinoma is the most common cancer of the kidneys that is primarily treated with surgery, including removal of part or all the involved kidney depending on size and tumor, complexity, and patient characteristics. Partial nephrectomy historically was restricted to cases of solitary kidney or bilateral tumors. It was then started for masses smaller than 4 cm and currently is even studied and justified in tumors smaller than 7 cm if surgically feasible. Although partial nephrectomy preserves kidney tissue and, therefore, delays or prevents the new onset of CKD and ESRD, radical nephrectomy is still overused even for the small tumors. Studies have shown that although this practice is driven by an easier complete removal of the kidney especially in the era of minimally invasive surgery, partial nephrectomy is successful in curing cancer and achieving excellent cancer-specific survival in addition to its benefits on cardiovascular health. Nowadays interest in preserving healthy kidney tissue is increasing to the level of studying the impact of larger volume removed around the kidney and the histopathology of that non-neoplastic tissue to predict kidney function behavior postoperatively.

Fetal programming and cardiovascular pathology

Low birth weight serves as a crude proxy for impaired growth during fetal life and indicates a failure for the fetus to achieve its full growth potential. Low birth weight can occur in response to numerous etiologies that include complications during pregnancy, poor prenatal care, parental smoking, maternal alcohol consumption, or stress. Numerous epidemiological and experimental studies demonstrate that birth weight is inversely associated with blood pressure and coronary heart disease. Sex and age impact the developmental programming of hypertension. In addition, impaired growth during fetal life also programs enhanced vulnerability to a secondary insult. Macrosomia, which occurs in response to maternal obesity, diabetes, and excessive weight gain during gestation, is also associated with increased cardiovascular risk. Yet, the exact mechanisms that permanently change the structure, physiology, and endocrine health of an individual across their lifespan following altered growth during fetal life are not entirely clear. Transmission of increased risk from one generation to the next in the absence of an additional prenatal insult indicates an important role for epigenetic processes. Experimental studies also indicate that the sympathetic nervous system, the renin angiotensin system, increased production of oxidative stress, and increased endothelin play an important role in the developmental programming of blood pressure in later life. Thus, this review will highlight how adverse influences during fetal life and early development program an increased risk for cardiovascular disease including high blood pressure and provide an overview of the underlying mechanisms that contribute to the fetal origins of cardiovascular pathology.

A prospective controlled study of living kidney donors: three-year follow-up

BACKGROUND

There have been few prospective controlled studies of kidney donors. Understanding the pathophysiologic effects of kidney donation is important for judging donor safety and improving our understanding of the consequences of reduced kidney function in chronic kidney disease.

STUDY DESIGN

Prospective, controlled, observational cohort study.

SETTING & PARTICIPANTS

3-year follow-up of kidney donors and paired controls suitable for donation at their donor's center.

PREDICTOR

Kidney donation.

OUTCOMES

Medical history, vital signs, glomerular filtration rate, and other measurements at 6, 12, 24, and 36 months after donation.

RESULTS

At 36 months, 182 of 203 (89.7%) original donors and 173 of 201 (86.1%) original controls continue to participate in follow-up visits. The linear slope of the glomerular filtration rate measured by plasma iohexol clearance declined 0.36±7.55mL/min per year in 194 controls, but increased 1.47±5.02mL/min per year in 198 donors (P=0.005) between 6 and 36 months. Blood pressure was not different between donors and controls at any visit, and at 36 months, all 24-hour ambulatory blood pressure parameters were similar in 126 controls and 135 donors (mean systolic blood pressure, 120.0±11.2 [SD] vs 120.7±9.7mmHg [P=0.6]; mean diastolic blood pressure, 73.4±7.0 vs 74.5±6.5mmHg [P=0.2]). Mean arterial pressure nocturnal dipping was manifest in 11.2% ± 6.6% of controls and 11.3% ± 6.1% of donors (P=0.9). Urinary protein-creatinine and albumin-creatinine ratios were not increased in donors compared with controls. From 6 to 36 months postdonation, serum parathyroid hormone, uric acid, homocysteine, and potassium levels were higher, whereas hemoglobin levels were lower, in donors compared with controls.

LIMITATIONS

Possible bias resulting from an inability to select controls screened to be as healthy as donors, short follow-up duration, and dropouts.

CONCLUSIONS

Kidney donors manifest several of the findings of mild chronic kidney disease. However, at 36 months after donation, kidney function continues to improve in donors, whereas controls have expected age-related declines in function.

Long term prospective assessment of living kidney donors: single center experience

Virtually, all studies reporting the outcomes of living kidney donation beyond the first year from donation were retrospective. In this prospective study, the outcome of 81 consecutive living kidney donors was thoroughly evaluated. Clinical, laboratory, and radiological assessments were carried out at predonation (basal), 3, 6, 12, and 24 months after donation. The mean age at time of donation was 37.8 ± 9.8 years and the majority was females (75.3%). The mean BMI increased significantly after donation (P < 0.04). The mean serum creatinine levels (mg/dl) were 0.75 ± 0.14, 1.01 ± 0.22, 0.99 ± 0.21, 0.98 ± 0.20, and 0.94 ± 0.20 (P < 0.0001). Likewise, the mean levels of measured creatinine clearance (mL/min) were 148.8 ± 35.7, 94.7 ± 26.6, 95.5 ± 24.6, 96.7 ± 20.2, and 101.6 ± 26.2 (P < 0.0001). The mean 24 hours urinary protein excretion (gm/dL) were 0.09 ± 0.03, 0.19 ± 0.18, 0.16 ± 0.09, 0.18 ± 0.25, and 0.17 ± 0.12 (P < 0.0001). There were significant increases in the means of the longitudinal and transverse diameters of the remaining kidney over time (P < 0.001). Out of 42 female donors, eleven female donors have got successful postdonation pregnancies. There were no reported surgical complications, either intra- or postoperative. Long-term follow-up is necessary for all living kidney donors through local institutional and world registries. This trial is registered with ClinicalTrials.gov NCT00813579.

Is microalbuminuria a risk factor for hypertension in children with solitary kidney?

BACKGROUND

The correlations between ambulatory blood pressure measurements (ABPM) and serum cystatin C (Cys C), serum creatinine (Cr), microalbumin (MA), and β2-microglobulin (β2-MG) levels in 24 h (24-h) urine were analyzed in children with solitary kidney (SK) and compared to healthy children.

METHODS

Fifty children with normal functioning SK and 25 controls were studied. The ABPM, serum Cys C, serum Cr, MA, and β2-MG levels in 24-h urine were measured in all children. Clinical symptoms and signs, laboratory results, urinary ultrasonography, voiding cystourethrography, and Dimercaptosuccinic acid (DMSA) scintigraphy results were recorded in the SK group. Four patients with Wilms' tumor and two with renal scarring were excluded from the study.

RESULTS

The mean ages of the SK group and controls were 9.6 ± 3.6 and 9.3 ± 3.3 years, respectively. The serum Cys C and Cr levels, 24-h urinary β2-MG and MA levels were similar in both groups (p > 0.05). However, 24-h urinary MA excretion was higher in patients living with SK more than 5 years (p = 0.01). Standard deviation scores of ABPM parameters showed no significant correlation with serum Cr, serum Cys C, MA, and β2-MG in 24-h urine of both groups.

CONCLUSIONS

Children with SK have increased 24-h urinary MA excretion in the long term, and need prolonged follow-up to detect early deterioration of renal function and to prevent end-organ damage later in life.

Renal parenchymal thickness in children with solitary functioning kidney

BACKGROUND

Reduced renal parenchymal thickness (PT) is a parameter used by clinicians to assess the degree of hydronephrosis. In patients with a congenital hydronephrotic solitary functioning kidney (SFK), PT is difficult to determine as there is no comparison with the contralateral kidney. The aim of this study was to obtain ultrasound measurements of PT in children with normal SFK and to compare these data with PT measurements in children with two functioning kidneys.

METHODS

This was a prospective multicenter study carried out between 2006 and 2011 in which 236 children aged 11 days to 18.96 years with healthy SFK were examined. The SFK etiologies were unilateral renal agenesis or a nonfunctioning contralateral kidney, mostly due to multicystic dysplasia. In addition to determining other parameters, we measured PT in the middle third of the kidney by ultrasound. Correlations between PT and age, height and weight were assessed.

RESULTS

Correlation analysis showed a positive correlation with renal PT for all parameters. The correlation coefficients for age, height and weight were 0.863, 0.873 and 0.874, respectively. In most age categories, the renal parenchyma was significantly thicker in the SFK than in two functioning kidneys.

CONCLUSIONS

Based on our results, we suggest that PT in the SFK is correlated with height, weight and age of the patient. Consequently, measurements of PT may be used for monitoring the development of the healthy SFK and may contribute to a more accurate assessment of the severity of SFK anomalies.

Is solitary kidney really more resistant to ischemia? An experimental canine study

PURPOSE

To our knowledge there are no evidence-based medicine data to date to critically judge the vulnerability of a solitary kidney to warm ischemia compared to paired kidneys.

MATERIALS AND METHODS

Ten dogs were exposed to open right nephrectomy to create a solitary kidney model (group 1). Ten dogs with both kidneys were considered group 2. All dogs underwent warm ischemia by open occlusion of the left renal artery for 90 minutes. Dogs were sacrificed at different intervals (3 days to 4 weeks). All dogs were reevaluated by renogram before sacrifice and histopathology of the investigated kidney. The proinflammatory markers CD95 and tumor necrosis factor-α were assessed using real-time polymerase chain reaction.

RESULTS

In group 1 clearance decreased by 20% at 1 week but basal function was regained starting at week 2. In group 2 clearance decreased more than 90% up to week 2. Recovery started at week 3 and by 4 weeks there was a 23% clearance reduction. Histopathological examination in group 1 revealed significant tubular necrosis (60%) at 3 days with regeneration starting at 1 week. In group 2 there was more pronounced tubular necrosis (90%) with regeneration starting at 2 weeks. The expression of proinflammatory markers was up-regulated in each group with higher, more sustained expression in group 2.

CONCLUSIONS

Solitary kidney in a canine model is more resistant to ischemia than paired kidneys based on radiological, pathological and genetic evidence.

Long-term renal function, complications and life expectancy in living kidney donors

Living kidney transplantation is now a widely accepted treatment for end stage renal disease (ESRD) because it provides excellent outcomes for recipients. However, long-term outcomes of living kidney donors have not been well understood. Because securing the safety of the donor is essential to the continued success of this procedure, we reviewed articles discussing long-term outcomes of living kidney donors. Most studies found no decrease in long-term survival or progressive renal dysfunction in previous kidney donors. Moreover, the prevalence of hypertension was comparable to that expected in the general population, although some did report otherwise. Urinary protein showed small increases in this population and was associated with hypertension and a lower glomerular filtration rate. Quality of life following living kidney donation seems to be better than the national norm. We also encountered several reports of ESRD in previous living kidney donors. Regular follow-up of kidney donors is recommended and future controlled, prospective studies will better delineate risk factors which cause health problems following living kidney donation.

Age, gender, and body mass index are associated with renal function after kidney donation

Renal function is thoroughly evaluated before live kidney donation. However, some donors experience impaired recovery of renal function after donation. Our aim was to assess estimated glomerular filtration rate (eGFR) and mean relative (%) increase in creatinine one yr after donor nephrectomy. The study was based on retrospective data from kidney donors during the period 1997-2009. Pre-operative and one-yr follow-up data were available for 721 of 1067 donors. Mean relative increase in creatinine and eGFR were stratified by gender, body mass index (BMI), and age at donation. At one yr post-donation, overweight (BMI > 5 kg/m(2) ) women 50 yr or older experienced the lowest eGFR of 49.6 ± 8.8 mL/min/1.73 m(2) . Men younger than 50 yr with normal weight (BMI < 25 kg/m(2) ) had the highest eGFR of 66.6 ± 10.4 mL/min/1.73 m(2) . Overweight men 50 yr or older had the highest relative increase in creatinine of 49.4% compared to pre-donation. Men under 50 yr with normal weight had the smallest increase in creatinine of 35.2%. In multivariate analysis, older age (p < 0.001), male gender (p < 0.001), and overweight (p = 0.01) were associated with relative increase in creatinine after donation. Potential donors should be offered counseling regarding overweight, as this is a modifiable risk factor.

Kidney aging--inevitable or preventable?

The aging process affects all organs, including the kidneys. As part of this process, progressive scarring and a measurable decline in renal function occur in most people over time. The improved understanding of the processes that can lead to and/or hasten scarring and loss of renal function over time parallels advances in our understanding of the aging process. Clinical factors, including hypertension, diabetes mellitus, obesity, abnormal lipid levels and vitamin D deficiency, have been associated with increasing renal sclerosis with age. In addition, tissue factors such as angiotensin II, advanced glycation end products, oxidative stress and Klotho are associated with renal aging. These associations and possible interventions, including the control of blood pressure, blood sugar, weight, diet and calorie restriction might make renal aging more preventable than inevitable.

Understanding the effects of chronic kidney disease on cardiovascular risk: are there lessons to be learnt from healthy kidney donors?

Chronic kidney disease (CKD) is now a recognized global public health problem. It is highly prevalent and strongly associated with hypertension and cardiovascular disease (CVD); far more patients with a glomerular filtration rate below 60 ml min(-1) per 1.73 m(2) will die from cardiovascular causes than progress to end-stage renal disease. A better understanding of the complex mechanisms underlying the development of CVD among CKD patients is required if we are to begin devising therapy to prevent or reverse this process. Observational studies of CVD in CKD are difficult to interpret because renal impairment is almost always accompanied by confounding factors. These include the underlying disease process itself (for example, diabetes mellitus and systemic vasculitis) and the complications of CKD, such as hypertension, anaemia and inflammation. Kidney donors provide an ideal opportunity to study healthy subjects without manifest vascular disease who experience an acute change from having normal to modestly impaired renal function at the time of uninephrectomy. Prospectively examining the cardiovascular consequences of uninephrectomy using donors as a model of CKD may provide useful insight into the pathophysiology of CVD in CKD and, therefore, into how the CVD risk associated with renal impairment might eventually be reduced.

Race and renal function early after live kidney donation: an analysis of the United States Organ Procurement and Transplantation Network Database

Among Americans, the risk for kidney disease is higher in individuals of African descent (AA) when compared with Caucasians. We considered whether there are similar racial differences in kidney function soon after donor nephrectomy. Of the 31,928 live kidney donors that donated between the years 2000 and 2005, 16,996 (53%) had post-donation serum creatinine recorded at a mean follow-up of 156 d (range 1-1410 d). A total of 14,525 (85%) were Caucasians and 2471 (15%) were AA. When compared with Caucasians, AA donors were more likely to be younger, heavier, and male, had a higher baseline serum creatinine and a shorter duration of follow-up. After accounting for these differences, the serum creatinine after donation and fractional rise in serum creatinine after donation were similar between the two groups (AA vs. Caucasian donors, 1.3 ± 0.3 vs. 1.2 ± 0.3 mg/dL; 53% vs. 45%) and the post-donation estimated glomerular filtration rate was also similar (57.2 ± 0.6 vs. 56.0 ± 0.2 mL/min per 1.73 m(2)). We observed no major clinical difference in glomerular filtration rate and ability to compensate for loss of renal mass soon after live kidney donation between Caucasian and AA donors.

Congenital versus acquired solitary kidney: is the difference relevant?

BACKGROUND

Serious concerns have risen during the last decades regarding the potential role of solitary kidney (SK) in promoting systemic hypertension, proteinuria and glomerulosclerosis. The aim of the study was to assess mid- and long-term outcome of children with SK, with special highlight on the differential functional outcome of congenital and acquired forms of SK.

METHODS

Ninety-seven patients (43 females) aged from 2.9 to 25 years with radiologically normal SK were divided into two groups depending on whether they had a congenital (CSK, n = 44) or an acquired SK (ASK, n = 53). Mean follow-up time with SK was 8.3 ± 3.2 and 9.1 ± 4.4 years, respectively (P = NS). Blood pressure (BP), glomerular filtration rate (GFR) measured by inulin clearance, and microalbuminuria were assessed in all patients.

RESULTS

Two children (2%), one in each group, had systemic hypertension confirmed by 24-h ambulatory BP monitoring, and 17 (17.5%) had a significant microalbuminuria (8 in CSK and 9 in ASK, P = NS). The overall mean GFR was 100.6 ± 15 mL/min/1.73 m(2) and was found to be inversely correlated with age and follow-up time. Seven children had a GFR <80 mL/min/1.73 m(2), all had been nephrectomized in early childhood. Interestingly, GFR was higher in CSK than in ASK group (107.2 vs. 95.2 mL/min/1.73 m(2), P < 0.01) and was negatively related to follow-up time only in the latter but not in the former group.

CONCLUSIONS

In the light of these results, it appears that renal function in children with SK is well preserved in short and medium term, but it seems to decline gradually with longer periods of follow-up, particularly in ASK, thus assuming a better functional adaptation in CSK. Both conditions remain yet risky and predispose children to a greater incidence of hypertension and renal impairment in later life. Thereby, careful screening should be proposed throughout childhood to detect early signs of glomerular hyperfiltration and prevent its progression to more serious complications.