Long-term Renal Function in Living Kidney Donors Who Had Histological Abnormalities at Donation

Consequences of low estimated glomerular filtration rate either before or early after kidney donation

In the general population, decreases in glomerular filtration rate (GFR) are associated with subsequent development of chronic kidney disease (CKD), cardiovascular disease (CVD), and death. It is unknown if low estimated GFR (eGFR) before or early after kidney donation was also associated with these risks. One thousand six hundred ninety-nine living donors who had both predonation and early (4-10 weeks) postdonation eGFR were included. We studied the relationships between eGFR, age at donation, and the time to sustained eGFR<45 (CKD stage 3b) and <30 mL/min/1.73m2 (CKD stage 4), hypertension, diabetes mellitus (DM), CVD, and death. Median follow-up was 12 (interquartile range, 6-21) years. Twenty-year event rates were 5.8% eGFR<45 mL/min/1.73m2; 1.2% eGFR<30 mL/min/1.73m2; 29.0% hypertension; 7.8% DM; 8.0% CVD; and 5.2% death. The median time to eGFR<45 mL/min/1.73m2 (N = 79) was 17 years, and eGFR<30 mL/min/1.73m2 (N = 22) was 25 years. Both low predonation and early postdonation eGFR were associated with eGFR<45 mL/min/1.73m2 (P < .0001) and eGFR<30 mL/min/1.73m2 (P < .006); however, the primary driver of risk for all ages was low postdonation (rather than predonation) eGFR. Predonation and postdonation eGFR were not associated with hypertension, DM, CVD, or death. Low predonation and early postdonation eGFR are risk factors for developing eGFR<45 mL/min/1.73m2 (CKD stage 3b) and <30 mL/min/1.73m2 (CKD stage 4), but not CVD, hypertension, DM, or death.

Presumed Monozygotic Twin Kidney Transplantation with a Thin Basement Membrane Nephropathy Donor: A Case Report

Identical or Monozygotic twin kidney transplant usually possess an excellent immunological match and provide the opportunity to minimize or even avoid immunosuppression toxicity. However, there are concerns regarding disease recurrence among end stage kidney disease (ESKD) patients with an unknown etiology. Together with the risk of inherent, familial disease affecting donors and recipients alike, more invasive tests such as a pretransplant biopsy are being considered to ascertain renal prognosis. A 30-year-old female, known case of CKD Stage 5D from an unknown etiology, with secondary hyperparathyroidism and heart failure, presented at our OPD for kidney transplantation. Her donor is her identical twin who is asymptomatic and denies comorbidities. The recipient discloses a previous history of blood transfusion. Immunological workup revealed the following: matched blood type, zero HLA mismatch, negative T-cell tissue crossmatch but with a positive Class I HLA antigen screen. Antibody specificity revealed the presence of donor specific antibodies (DSA). After workup completion, the patient underwent a right kidney transplant with a preimplantation wedge biopsy on the donor kidney. Immediate graft function was noted post operatively. The wedge biopsy revealed a thinned glomerular basement membrane, consistent with Thin Basement Membrane Nephropathy (TBMN). The patient was started on immunosuppression and prophylaxis during the duration of the post operative period without any complications. Five months post-transplant, both the recipient and donor maintain an adequate renal function without any signs of allograft rejection. In this case report, we have demonstrated that TBMN may serve as a viable donor for a presumed monozygous twin kidney transplantation. When a live donor with TBMN is being considered, a thorough work-up and identification of high-risk features are essential to exclude other progressive renal diseases during the pretransplant evaluation.

Association of Implantation Biopsy Findings in Living Donor Kidneys With Donor and Recipient Outcomes

RATIONALE & OBJECTIVE

Some living donor kidneys are found to have biopsy evidence of chronic scarring and/or glomerular disease at implantation, but it is unclear if these biopsy findings help predict donor kidney recovery or allograft outcomes. Our objective was to identify the prevalence of chronic histological changes and glomerular disease in donor kidneys, and their association with donor and recipient outcomes.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

Single center, living donor kidney transplants from January 2010 to July 2022.

EXPOSURE

Chronic histological changes, glomerular disease in donor kidney implantation biopsies.

OUTCOME

For donors, single-kidney estimated glomerular filtration rate (eGFR) increase, percent total eGFR loss, ≥40% eGFR decline from predonation baseline, and eGFR<60mL/min/1.73m2 at 6 months after donation; for recipients, death-censored allograft survival.

ANALYTICAL APPROACH

Biopsies were classified as having possible glomerular disease by pathologist diagnosis or chronic changes based on the percentage of glomerulosclerosis, interstitial fibrosis/tubular atrophy, and vascular disease. We used logistic regression to identify factors associated with the presence of chronic changes, linear regression to identify the association between chronic changes and single-kidney estimated glomerular filtration rate (eGFR) recovery, and time-to-event analyses to identify the relationship between abnormal biopsy findings and allograft outcomes.

RESULTS

Among 1,104 living donor kidneys, 155 (14%) had advanced chronic changes on implantation biopsy, and 12 (1%) had findings suggestive of possible donor glomerular disease. Adjusted logistic regression showed that age (odds ratio [OR], 2.44 per 10 years [95% CI, 1.98-3.01), Hispanic ethnicity (OR, 1.87 [95% CI, 1.15-3.05), and hypertension (OR, 1.92 [95% CI, 1.01-3.64), were associated with higher odds of chronic changes on implantation biopsy. Adjusted linear regression showed no association of advanced chronic changes with single-kidney eGFR increase or relative risk of eGFR<60mL/min/1.73m2. There were no differences in time-to-death-censored allograft failure in unadjusted or adjusted Cox proportional hazards models when comparing kidneys with chronic changes to kidneys without histological abnormalities.

LIMITATIONS

Retrospective, absence of measured GFR.

CONCLUSIONS

Approximately 1 in 7 living donor kidneys had chronic changes on implantation biopsy, primarily in the form of moderate vascular disease, and 1% had possible donor glomerular disease. Abnormal implantation biopsy findings were not significantly associated with 6-month donor eGFR outcomes or allograft survival.

PLAIN-LANGUAGE SUMMARY

Kidney biopsies are the gold standard test to identify the presence or absence of kidney disease. However, kidneys donated by healthy living donors-who are extensively screened for any evidence of kidney disease before donation-occasionally show findings that might be considered "abnormal," including the presence of scarring in the kidney or findings suggestive of a primary kidney disease. We studied the frequency of abnormal kidney biopsy findings among living donors at our center. We found that about 14% of kidneys had chronic abnormalities and 1% had findings suggesting possible glomerular kidney disease, but the presence of abnormal biopsy findings was not associated with worse outcomes for the donors or their recipients.

Τhe Impact of Pre-Transplant Kidney Biopsy on the Evaluation of Prospective Living Kidney Donors

Living kidney donation contributes to increasing the donor pool. Since safety and excellent outcomes of living kidney donors (LKD) are essential, renal biopsy must be part of the pre-transplant evaluation in donors with isolated urine abnormalities or other risk factors. We retrospectively collected data on potential living donors evaluated in the pre-transplant outpatient clinic of Laiko General Hospital of Athens between 2007 and 2022, who underwent a pre-transplant biopsy. Biopsy indications included microscopic hematuria, borderline proteinuria and comorbidities suggestive of chronicity. Those with glomerular diseases or chronic lesions were excluded from donation. We identified 59 potential living donors who underwent renal biopsy. Of these, 10 (16.9%) were male. Median age was 58 (IQR 51-63) years, while 23 (39%) were older than 60 years. 49 out of 59 (83%) had glomerular hematuria, 10 (16.7%) had proteinuria (150-300 mg/d). Out of the 59 donors, 21 (35.6%) were hypertensive, three (5.1%) had impaired glucose tolerance and seven (11.9%) had a BMI > 30 kg/m². A total of 32 (54.2%) potential donors were accepted for donation. Eight (13.6%) had IgA nephropathy, 10 (16.9%) TBMD and nine (15.3%) had increased chronicity including secondary FSGS. When compared with a control group of donors who did not need a pre-transplant biopsy, those 32 who donated were more frequently hypertensive (p = 0.003), but had similar eGFR [61.3 (±10.4) vs. 61.9 (±13.8), p = 0.866] after a follow-up of 79 (36-114) months. Renal biopsy is a useful tool in the evaluation of prospective LKD. Thorough assessment of donors with isolated urine abnormalities and marginal donors is critical to ensure good post-donation outcomes.

Prediction of Renal Function in Living Kidney Donors and Recipients of Living Donor Kidneys Using Quantitative Histology

BACKGROUND

Living kidney donors (LKDs) are at increased risk of chronic kidney disease, whereas transplant recipients experience progressive reduction of graft function. We examined the predictive value of quantitative stereology on renal function in LKDs and recipients of living donor kidneys, based on perioperative biopsies from the donated kidney.

METHODS

Cortex volume of both donor kidneys was determined by contrast-enhanced computed tomography and single-kidney glomerular filtration rate (GFR) by 51 chrome-EDTA clearance together with renography. Glomerular density was used to estimate total glomeruli number in addition to glomerular volume, glomerular sclerosis, kidney fibrosis, and arteriole dimensions. GFR measurements were repeated 1 y after transplantation in both LKDs and recipients. Associations between GFR at follow-up and cortex volume and histomorphometric parameters after adjustment of age, gender, body mass index, smoking status, 24-h blood pressure, and single-kidney GFR were examined.

RESULTS

We included 49 LKDs (age, 51 ± 12 y) and 51 recipients (age, 44 ± 13 y). At follow-up, GFR was 71 ± 16 mL/min in LKDs and 61 ± 18 mL/min in recipients with hyperfiltration being more prominent in LKDs (30.4%) as compared to recipients (16.4%; P < 0.05). One-year GFR in donors correlated to cortex volume ( P < 0.001) but not to any histological parameters, whereas GFR in recipients correlated to the amount of interstitial fibrosis ( P < 0.01) but not to other histological parameters or cortex volume.

CONCLUSIONS

Kidney cortex volume, but not renal histology parameters, predicts 1-y renal outcome in LKDs. In contrast, the amount of interstitial fibrosis, but not cortex volume, predicts 1-y graft function in recipients.

Acute kidney injury and the compensation of kidney function after nephrectomy in living donation

Acute kidney injury (AKI) incidence is growing rapidly, and AKI is one of the predictors of inpatient mortality. After nephrectomy, all the patients have decreased kidney function with AKI and recover from AKI. However, the characteristic and behavior of AKI is different from usual AKI and compensatory kidney function has been well known in the postoperative setting, especially in living donors. In this review, we have focused on the compensation of kidney function after nephrectomy in living donors. We discuss factors that have been identified as being associated with kidney recovery in donors including age, sex, body mass index, remnant kidney volume, estimated glomerular filtration rate, and various comorbidities.

Pearls and Pitfalls in Pediatric Kidney Transplantation After 5 Decades

Worldwide, over 1,300 pediatric kidney transplantations are performed every year. Since the first transplantation in 1959, healthcare has evolved dramatically. Pre-emptive transplantations with grafts from living donors have become more common. Despite a subsequent improvement in graft survival, there are still challenges to face. This study attempts to summarize how our understanding of pediatric kidney transplantation has developed and improved since its beginnings, whilst also highlighting those areas where future research should concentrate in order to help resolve as yet unanswered questions. Existing literature was compared to our own data of 411 single-center pediatric kidney transplantations between 1968 and 2020, in order to find discrepancies and allow identification of future challenges. Important issues for future care are innovations in immunosuppressive medication, improving medication adherence, careful donor selection with regard to characteristics of both donor and recipient, improvement of surgical techniques and increased attention for lower urinary tract dysfunction and voiding behavior in all patients.

[Living donor nephrectomy: The French guidelines from CTAFU]

OBJECTIVE

To propose surgical recommendations for living donor nephrectomy.

METHOD

Following a systematic approach, a review of the literature (Medline) was conducted by the CTAFU regarding functional and anatomical assessment of kidney donors, including which side the kidney should be harvested from. Distinct surgical techniques and approaches were evaluated. References were considered with a predefined process to propose recommendations with the corresponding levels of evidence.

RESULTS

The recommendations clarify the legal and regulatory framework for kidney donation in France. A rigorous assessment of the donor is one of the essential prerequisites for donor safety. The impact of nephrectomy on kidney function needs to be anticipated. In case of modal vascularization of both kidneys without a relative difference in function or urologic abnormality, removal of the left kidney is the preferred choice to favor a longer vein. Mini-invasive approaches for nephrectomy provide faster donor recovery, less donor pain and shorter hospital stay than open surgery.

CONCLUSION

These French recommendations must contribute to improving surgical management of candidates for kidney donation.

Long-term impact of baseline serum uric acid levels on living kidney donors: a retrospective study

BACKGROUND

Preoperative characteristics of living kidney donors are commonly considered during donor selection and postoperative follow-up. However, the impact of preoperative uric acid (UA) levels is poorly documented. The aim of this study was to evaluate the association between preoperative serum UA levels and post-donation long-term events and renal function.

METHODS

This was a single-center retrospective analysis of 183 living kidney donors. The donors were divided into high (≥5.5 mg/dl) and low (< 5.5 mg/dl) UA groups. We analyzed the relationship between preoperative UA levels and postoperative estimated glomerular filtration rate (eGFR), as well as adverse events (cardiovascular events and additional prescriptions for hypertension, gout, dyslipidemia, and diabetes mellitus), over 5 years after donation.

RESULTS

In total, 44 donors experienced 52 adverse events over 5 years. The incidence of adverse events within 5 years was significantly higher in the high UA group than in the low UA group (50% vs. 24%, p = 0.003); this was true even after the exclusion of hyperuricemia-related events (p = 0.047). UA emerged as an independent risk factor for adverse events (p = 0.012). Donors with higher UA levels had lower eGFRs after donation, whereas body mass index, hemoglobin A1c, blood pressure, and low-density lipoprotein cholesterol did not have any impact on the eGFR.

CONCLUSIONS

The findings suggest that preoperative UA levels should be considered during donor selection and postoperative follow-up.

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.

Larger Nephron Size and Nephrosclerosis Predict Progressive CKD and Mortality after Radical Nephrectomy for Tumor and Independent of Kidney Function

BACKGROUND

Nephron hypertrophy and nephrosclerosis may be important determinants of CKD and mortality. However, studies of outcomes associated with these microstructural features have been limited to small tissue specimens from patients selected for either good kidney health or known kidney disease.

METHODS

To determine whether microstructural features are predictive of progressive CKD and mortality outcomes, we studied patients who underwent a radical nephrectomy for a tumor. Large wedge sections of renal parenchyma distal to the tumor were stained and scanned into high-resolution images; we annotated the cortex and all glomeruli to calculate glomerular volume, cortex volume per glomerulus, and percentage of globally sclerotic glomeruli. Morphometric measurements also included percentages of artery luminal stenosis and interstitial fibrosis/tubular atrophy (IF/TA) of the cortex. At follow-up visits every 6-12 months, we determined which patients experienced progressive CKD (defined as dialysis, kidney transplantation, or a 40% decline from postnephrectomy eGFR). Cox models for these outcomes were adjusted for age, sex, body mass index, hypertension, diabetes, smoking, eGFR, and proteinuria.

RESULTS

Among 936 patients (mean age, 64 years; postnephrectomy baseline eGFR, 48 ml/min per 1.73 m²), 117 progressive CKD events, 183 noncancer deaths, and 116 cancer deaths occurred during a median follow-up of 6.4 years. Larger glomerular volume, larger cortex per glomerulus, and higher percentage of globally sclerotic glomeruli or IF/TA predicted progressive CKD. Higher percentage IF/TA also predicted noncancer mortality. Microstructural features did not predict cancer mortality or recurrence.

CONCLUSIONS

After a radical nephrectomy, larger nephrons and nephrosclerosis predicted progressive CKD, and IF/TA predicted noncancer mortality. Morphometric analysis of renal parenchyma can predict noncancer clinical events in patients long after their radical nephrectomy.

Evaluation of postoperative kidney function after administration of 6% hydroxyethyl starch during living-donor nephrectomy for transplantation

PURPOSE

We aimed to investigate whether 6% HES 130/0.4 was associated with postoperative reduction of estimated glomerular filtration rate (eGFR) in donor patients who underwent nephrectomy for living kidney transplantation.

METHODS

This retrospective study included 213 living kidney transplant donors treated at Kyushu University Hospital in Japan from April 2014 to March 2018. Patients who were administered 6% HES 130/0.4 were allocated in the HES group (n = 108), and those who were not were allocated in the control group (n = 105). The postoperative decrements in estimated glomerular filtration rates (eGFRs) from preoperative values were calculated on postoperative days (PODs) 1, 3, and 14. Decline in kidney function (DKF) according to the Kidney Disease: Improving Global Outcomes (KDIGO) classification were analyzed by multivariable-adjusted ordinal logistic regression to estimate odds ratios (ORs) for postoperative DKF.

RESULTS

In HES group, administration amount of HES was median 9.4 [interquartile range: 8.2-14.3] ml/kg. Postoperative decrements in eGFR were similar in the control and HES groups on POD 1 (control group: mean 32.0 vs. HES group: 33.0 mL/min/1.73 m²), same as POD 3 (21.1 vs. 22.4 mL/min/1.73 m²) and POD 14 (26.0 vs. 25.9 mL/min/1.73 m²), even after adjusting for confounding factors. The multivariable-adjusted ORs for postoperative DKF did not significantly increase in the HES group on POD 1 (OR: 0.88), POD 3 (OR: 0.96), and POD 14 (OR: 0.52) compared with the control group.

CONCLUSION

Six percent HES 130/0.4 is not associated with postoperative renal dysfunction in donor patients undergoing nephrectomy for kidney transplantation.

Association Between Living Kidney Donor Postdonation Hypertension and Recipient Graft Failure

BACKGROUND

Recipients of kidneys from living donors who subsequently develop end-stage renal disease (ESRD) also have higher graft failure, suggesting the 2 donor kidneys share risk factors that could inform recipient outcomes. Given that donor ESRD is rare, an earlier and more common postdonation outcome could serve as a surrogate to individualize counseling and management for recipients. Hypertension is a frequent event before donor ESRD; thus, early postdonation hypertension might indicate higher risk of graft failure.

METHODS

We studied Scientific Registry of Transplant Recipients data to quantify the association between early postdonation hypertension and recipient graft failure using propensity score-weighted Cox proportional hazards regression. We also examined the association between postdonation systolic blood pressure and graft failure.

RESULTS

Of 37 901 recipients, 2.4% had a donor who developed hypertension within 2 years postdonation. Controlling for donor and recipient characteristics, recipients whose donors developed hypertension had no higher risk for graft failure (adjusted hazard ratio [aHR] 1.03, 95% confidence interval [CI] 0.85-1.25, P = 0.72). This was consistent among subgroups of recipients at higher risk for adverse outcomes due to hyperfiltration: African American recipients (aHR 1.10, 95% CI 0.70-1.73, P = 0.68) and those with ESRD caused by hypertension (aHR 1.10, 95% CI 0.65-1.85, P = 0.73) or diabetes (aHR 0.80, 95% CI 0.56-1.13, P = 0.20). However, graft failure was associated with postdonation systolic blood pressure (per 10 mm Hg, aHR 1.05, 95% CI 1.03-1.08, P < 0.001).

CONCLUSIONS

Although postdonation systolic blood pressure is associated with graft failure, the reported diagnosis of hypertension as determined by the requirement for blood pressure treatment early postdonation did not portend a higher risk of recipient graft failure in the same way as eventual postdonation ESRD.

Kidney structural characteristics based on a kidney biopsy and contrast-enhanced computed tomography in healthy living kidney donors

The demands for kidney transplantations are increasing, and so is the number of live kidney donors (LKDs). Recent studies show that LKDs have an increased risk of developing end-stage renal disease compared with healthy non-donors. However, the knowledge about factors predicting renal disease in kidney donors is sparse. Some evidence points to increased glomerular sclerosis and kidney fibrosis, as well as a low number of glomeruli as associated with a worse renal outcome. This methodological study investigated that which estimates are obtainable with a standard kidney biopsy taken from the donated kidney during the transplantation, and a standard contrast-enhanced computed tomography (CT) in kidney donors. CT-scans were used to obtain total volume of the kidney and kidney cortex using the Cavalieri estimator and 2D-nucleator. Glomerular number density in the biopsies was estimated by a model-based method, and was multiplied by total cortex volume in order to estimate the total number of glomeruli in the kidney. Glomerular volume was estimated by the 2D-nucleator and a model-based stereological technique. Kidney fibrosis (point-counting), glomerular sclerosis (evaluation of glomerular profiles), and arteriole dimensions (2D-nucleator) were also estimated in the biopsy sections from the donated kidney. Various studies have attempted to identify predictors of renal outcome in LKDs. There is no consensus yet, and further studies are needed to elucidate if and how the estimates described in this study are associated with renal outcome in LKDs.

Factors related to suboptimal recovery of renal function after living donor nephrectomy: a retrospective study

Background

The renal function of the remaining kidney in living donors recovers up to 60~70% of pre-donation estimated-glomerular filtration rate (eGFR) by compensatory hypertrophy. However, the degree of this hypertrophy varies from donor to donor and the factors related to it are scarcely known.

Methods

We analyzed 103 living renal transplantations in our institution and divided them into two groups: compensatory hypertrophy group [optimal group, 1-year eGFR ≥60% of pre-donation, n = 63] and suboptimal compensatory hypertrophy group (suboptimal group, 1-year eGFR < 60% of pre-donation, n = 40). We retrospectively analyzed the factors related to suboptimal compensatory hypertrophy.

Results

Baseline eGFRs were the same in the two groups (optimal versus suboptimal: 82.0 ± 13.1 ml/min/1.73m² versus 83.5 ± 14.8 ml/min/1.73m², p = 0.588). Donor age (optimal versus suboptimal: 56.0 ± 10.4 years old versus 60.7 ± 8.7 years old, p = 0.018) and uric acid (optimal versus suboptimal: 4.8 ± 1.2 mg/dl versus 5.5 ± 1.3 mg/dl, p = 0.007) were significantly higher in the suboptimal group. The rate of pathological chronicity finding on 1-h biopsy (ah≧1 ∩ ct + ci≧1) was much higher in the suboptimal group (optimal versus suboptimal: 6.4% versus 25.0%, p = 0.007). After the multivariate analysis, the pathological chronicity finding [odds ratio (OR): 4.8, 95% confidence interval (CI): 1.3–17.8, p = 0.021] and uric acid (per 1.0 mg/dl, OR: 1.5, 95% CI: 1.1–2.2, p = 0.022) were found to be independent risk factors for suboptimal compensatory hypertrophy.

Conclusion

Chronicity findings on baseline biopsy and higher uric acid were associated with insufficient recovery of the post-donated renal function.

Long term evolution of renal function in essential hypertensive patients with no baseline proteinuria

Data on the long term evolution of renal function in essential hypertensive patients are scarce, showing a low incidence of end stage renal diseases but without information on how the renal function evolves. Our aim is to describe the long term evolution of renal function and possible trajectories in hypertensive patients. We included patients from an ongoing cohort with essential hypertension, no proteinuria at baseline and no diabetes during follow-up and with at least two creatinine dosages 4 years apart. A long term (average 16 years) follow-up was available in 609 patients (baseline age 51.8 ± 11.1 years, 52 % male, mean office BP 156//95 mmHg). The trajectories of creatinine were modeled through a flexible latent class mixed model. The analysis identified three classes of significantly different trajectories. In the first (n = 560), there was no significant variation of creatinine over time. In the second (n = 40), there was a significant rise of creatinine (117 ± 20 vs 85 ± 17 µmol/l, p < 0.0001). The third class (n = 9) was very heterogeneous, mainly composed of outliers. Further analysis showed the nonlinearity of the evolution of creatinine in classes 2 and 3. So the model of progressive renal deterioration in essential hypertension does not fit with our results. A large majority (92%) of patients show no significant change in creatinine level with time. In the others 8%, the increase in creatinine is not progressive but conversely show one or more sudden bouts of elevation.

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.

Post-transplant immunoglobulin A deposition and nephropathy in allografts

Post-transplant immunoglobulin A (IgA) nephropathy (IgAN) in the allograft is the major cause of allograft loss. Using a protocol biopsy, latent mesangial IgA deposition (IgAD) can be detected in the allograft. Latent IgAD is distinguished from IgAN by the absence of urinary abnormalities, although IgA is observed in the mesangium. However, the pathophysiology and most appropriate treatment strategy for latent mesangial IgAD in the allograft remain to be fully determined. Importantly, it is unknown whether all cases of post-transplant asymptomatic IgAD progress to symptomatic IgAN; indeed, IgA deposits disappear in some cases. The differences in allograft prognosis between asymptomatic IgAD and IgAN have also not been determined. Non-invasive methods of diagnosis of IgAD in the allograft using serological and pathological biomarkers are being developed. Possible serum biomarkers include serum galactose-deficient IgA1 (Gd-IgA1), Gd-IgA1-specific IgG and Gd-IgA1-specific IgA, and its immune complexes. Immunofluorescence analysis using Gd-IgA1 monoclonal antibody may provide a pathological biomarker. These serological and pathological biomarkers may be suitable for the characterization of the stage of IgAD. However, there is insufficient information regarding whether serological and pathological biomarkers can predict the progression of asymptomatic IgAD to symptomatic IgAN. We propose that the pathogenesis of IgAN can be defined through the clinical study of IgAD in the allograft using protocol biopsies conducted by nephrologists involved in clinical kidney transplantation.