Compensatory Structural and Functional Adaptation after Radical Nephrectomy for Renal Cell Carcinoma According to Preoperative Stage of Chronic Kidney Disease

Blockade of aryl hydrocarbon receptor restricts omeprazole-induced chronic kidney disease

Chronic kidney disease (CKD) is the 16th leading cause of mortality worldwide. Clinical studies have raised that long-term use of omeprazole (OME) is associated with the morbidity of CKD. OME is commonly used in clinical practice to treat peptic ulcers and gastroesophageal reflux disease. However, the mechanism underlying renal failure following OME treatment remains mostly unknown and the rodent model of OME-induced CKD is yet to be established. We described the process of renal injury after exposure to OME in mice; the early renal injury markers were increased in renal tubular epithelial cells (RTECs). And after long-term OME treatment, the OME-induced CKD mice model was established. Herein, aryl hydrocarbon receptor (AHR) translocation appeared after exposure to OME in HK-2 cells. Then for both in vivo and in vitro, we found that Ahr-knockout (KO) and AHR small interfering RNA (siRNA) substantially alleviated the OME-induced renal function impairment and tubular cell damage. Furthermore, our data demonstrate that antagonists of AHR and CYP1A1 could attenuate OME-induced tubular cell impairment in HK-2 cells. Taken together, these data indicate that OME induces CKD through the activation of the AHR-CYP axis in RTECs. Our findings suggest that blocking the AHR-CYP1A1 pathway acts as a potential strategy for the treatment of CKD caused by OME. KEY MESSAGES: We provide an omeprazole-induced chronic kidney disease (CKD) mice model. AHR activation and translocation process was involved in renal tubular damage and promoted the occurrence of CKD. The process of omeprazole nephrotoxicity can be ameliorated by blockade of the AHR-CYP1A1 axis.

Targeting Glomerular Hemodynamics for Kidney Protection

The kidney microcirculation is a unique structure as it is composed to 2 capillary beds in series: the glomerular and peritubular capillaries. The glomerular capillary bed is a high-pressure capillary bed, having a 60 mm Hg to 40 mm Hg pressure gradient, capable of producing an ultrafiltrate of plasma quantified as the glomerular filtration rate (GFR), thereby allowing for waste products to be removed and establishing sodium/volume homeostasis. Entering the glomerulus is the afferent arteriole, and the exiting one is the efferent arteriole. The concerted resistance of each of these arterioles is what is known as glomerular hemodynamics and is responsible for increasing or decreasing GFR and renal blood flow. Glomerular hemodynamics play an important role in how homeostasis is achieved. Minute-to-minute fluctuations in the GFR are achieved by constant sensing of distal delivery of sodium and chloride in the specialized cells called macula densa leading to upstream alternation in afferent arteriole resistance altering the pressure gradient for filtration. Specifically, 2 classes of medications (sodium glucose cotransporter-2 inhibitors and renin-angiotensin system blockers) have shown to be effective in long-term kidney health by altering glomerular hemodynamics. This review will discuss how tubuloglomerular feedback is achieved, and how different disease states and pharmacologic agents alter glomerular hemodynamics.

Identification of Hub Genes Involved in Tubulointerstitial Injury in Diabetic Nephropathy by Bioinformatics Analysis and Experiment Verification

Diabetic nephropathy (DN) is the most important cause of end-stage renal disease with a poorer prognosis and high economic burdens of medical treatments. It is of great research value and clinical significance to explore potential gene targets of renal tubulointerstitial lesions in DN. To properly identify key genes associated with tubulointerstitial injury of DN, we initially performed a weighted gene coexpression network analysis of the dataset to screen out two nonconserved gene modules (dark orange and dark red). The regulation of oxidative stress-induced intrinsic apoptotic signaling pathway, PI3K-Akt signaling pathway, p38MAPK cascade, and Th1 and Th2 cell differentiation were primarily included in Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways of these two modules. Next, 199 differentially expressed genes (DEGs) were identified via the limma package. Then, the GO annotation and KEGG pathways of the DEGs were primarily enriched in extracellular matrix (ECM) organization, epithelial cell migration, cell adhesion molecules (CAMs), NF-kappa B signaling pathway, and ECM-receptor interaction. Gene set enrichment analysis showed that in the DN group, the interaction of ECM-receptor, CAMs, the interaction of cytokine-cytokine receptor, and complement and coagulation cascade pathways were significantly activated. Eleven key genes, including ALB, ANXA1, ANXA2, C3, CCL2, CLU, EGF, FOS, PLG, TIMP1, and VCAM1, were selected by constructing a protein-protein interaction network, and expression validation, ECM-related pathways, and glomerular filtration rate correlation analysis were performed in the validated dataset. The upregulated expression of hub genes ANXA2 and FOS was verified by real-time quantitative PCR in HK-2 cells treated with high glucose. This study revealed potential regulatory mechanisms of renal tubulointerstitial damage and highlighted the crucial role of extracellular matrix in DN, which may promote the identification of new biomarkers and therapeutic targets.

Predicting GFR after radical nephrectomy: the importance of split renal function

PURPOSE

To evaluate a conceptually simple model to predict new-baseline-glomerular-filtration-rate (NBGFR) after radical nephrectomy (RN) based on split-renal-function (SRF) and renal-functional-compensation (RFC), and to compare its predictive accuracy against a validated non-SRF-based model. RN should only be considered when the tumor has increased oncologic potential and/or when there is concern about perioperative morbidity with PN due to increased tumor complexity. In these circumstances, accurate prediction of NBGFR after RN can be important, with a threshold NBGFR > 45 ml/min/1.73m² correlating with improved overall survival.

METHODS

236 RCC patients who underwent RN (2010-2012) with preoperative imaging (CT/MRI) and relevant functional data were included. NBGFR was defined as GFR 3-12 months post-RN. SRF was determined using semi-automated software that provides differential parenchymal-volume-analysis (PVA) from preoperative imaging. Our SRF-based model was: Predicted NBGFR = 1.24 (× Global GFR_Pre-RN) (× SRF_{Contralateral}), with 1.24 representing the mean RFC estimate from independent analyses. A non-SRF-based model was also assessed: Predicted NBGFR = 17 + preoperative GFR (× 0.65)-age (× 0.25) + 3 (if tumor > 7 cm)-2 (if diabetes). Alignment between predicted/observed NBGFR was assessed by comparing correlation coefficients and area-under-the-curve (AUC) analyses.

RESULTS

The correlation-coefficients (r) were 0.87/0.72 for SRF-based/non-SRF-based models, respectively (p = 0.005). For prediction of NBGFR > 45 ml/min/1.73m², the SRF-based/non-SRF-based models provided AUC of 0.94/0.87, respectively (p = 0.044).

CONCLUSION

Previous non-SRF-based models to predict NBGFR post-RN are complex and omit two important parameters: SRF and RFC. Our proposed model prioritizes these parameters and provides a conceptually simple, accurate, and clinically implementable approach to predict NBGFR post-RN. SRF can be easily obtained using PVA software that is affordable, readily available (FUJIFILM-Medical-Systems), and more accurate than nuclear-renal-scans. The SRF-based model demonstrates greater predictive-accuracy than a non-SRF-based model, including the clinically-important predictive-threshold of NBGFR > 45 ml/min/1.73m².

Postnephrectomy outcomes following en bloc resection of primary retroperitoneal sarcoma: multicentre study

This article reports on postoperative renal function in the largest series of patients with primary retroperitoneal sarcoma undergoing nephrectomy at three high-volume sarcoma centres. Although half of patients develop chronic kidney disease of stage 3 or higher, rarely do patients develop acute renal failure requiring renal replacement therapy.

Preoperative versus Postoperative Compensation of the Contralateral Normal Kidney in Patients Treated with Radical Nephrectomy for Renal Cell Carcinoma

Background: We sought to identify the factors affecting renal compensatory processes that occur preoperatively as well as postoperatively in patients treated with radical nephrectomy (RNx) for renal cell carcinoma (RCC). Methods: We retrospectively reviewed the records of 906 patients treated with RNx for RCC. We defined the early compensatory process (process 1) as compensatory adaptation of the contralateral normal kidney (CNK) before RNx. We defined the late compensatory process (process 2) as compensatory adaptation of the CNK after RNx. Total compensation was defined as the combination of these two processes. Multivariable logistic regression analyses were used to identify significant factors associated with processes 1, 2 and total compensation. Results: Mean preoperative, 1-week, and 5-year postoperative estimated glomerular filtration rates (eGFR) were 84.5, 57.6 and 63.7 mL/min/1.73 m², respectively. Female sex (p < 0.001), lower body mass index (BMI) (p < 0.001), absence of hypertension (p = 0.019), lower preoperative eGFR (p < 0.001), larger tumor volume (p < 0.001), and larger CNK volume (p < 0.001) were significantly associated with process 1. Younger age (p = 0.019), higher BMI (p < 0.001), and absence of diabetes mellitus (DM) (p = 0.033) were significantly associated with process 2. Female sex (p < 0.001), younger age (p < 0.001), absence of DM (p = 0.002), lower preoperative eGFR (p < 0.001), and larger tumor (p = 0.001) and CNK volumes (p < 0.001) were significantly associated with total compensation. Conclusions: Different factors affected each compensatory process. Process 1 made a greater contribution to the entire renal compensatory process than process 2.

Renal Cell Cancer and Chronic Kidney Disease

The association between chronic kidney disease (CKD) and renal cell carcinoma (RCC) is bidirectional and multifactorial. Risk factors such as hypertension, diabetes mellitus, obesity, and smoking increase the risk of both CKD and RCC. CKD can lead to RCC via an underlying cystic disease or oxidative stress. RCC can cause CKD because of the tumor itself, surgical reduction of renal mass (either partial or radical nephrectomy), and perioperative acute kidney injury. Medical therapies such as immune checkpoint inhibitors and vascular endothelial growth factor inhibitors can lead to acute kidney injury and resultant CKD. Clinicians need to be aware of the complex, bidirectional interplay between both diseases.

Machine learning-based prediction of acute kidney injury after nephrectomy in patients with renal cell carcinoma

The precise prediction of acute kidney injury (AKI) after nephrectomy for renal cell carcinoma (RCC) is an important issue because of its relationship with subsequent kidney dysfunction and high mortality. Herein we addressed whether machine learning (ML) algorithms could predict postoperative AKI risk better than conventional logistic regression (LR) models. A total of 4104 RCC patients who had undergone unilateral nephrectomy from January 2003 to December 2017 were reviewed. ML models such as support vector machine, random forest, extreme gradient boosting, and light gradient boosting machine (LightGBM) were developed, and their performance based on the area under the receiver operating characteristic curve, accuracy, and F1 score was compared with that of the LR-based scoring model. Postoperative AKI developed in 1167 patients (28.4%). All the ML models had higher performance index values than the LR-based scoring model. Among them, the LightGBM model had the highest value of 0.810 (0.783-0.837). The decision curve analysis demonstrated a greater net benefit of the ML models than the LR-based scoring model over all the ranges of threshold probabilities. The application of ML algorithms improves the predictability of AKI after nephrectomy for RCC, and these models perform better than conventional LR-based models.

Comparison of Risk Factors for the Development of Proteinuria After Radical Nephrectomy for Renal Cell Carcinoma

Purpose

We investigated compensatory structural hypertrophy and functional hyperfiltration in patients with renal cell carcinoma (RCC) after radical nephrectomy (RN) according to the presence of proteinuria.

Patients and Methods

We retrospectively enrolled 471 patients who underwent RN for RCC between October 2005 and December 2013. These patients were divided into two groups according to the presence of postoperative proteinuria (trace or greater (≥1+) urine dipstick). We obtained computed tomography images before and 1 year after surgery to calculate the functional renal volume (FRV). The preoperative and postoperative Chronic Kidney Disease Epidemiology Collaboration equation-calculated glomerular filtration rates (CKD-EPI GFRs) per unit FRV (GFR/FRV) were used to calculate the degree of hyperfiltration.

Results

The mean patient age was 54.7±11.1 years, and the mean preoperative CKD-EPI GFR, FRV, and GFR/FRV were 89.3±13.3 mL/min/1.73 m², 357.2±71.8 cm³, and 0.26±0.05 mL/min/1.73 m²/cm³, respectively. The percentage reduction rate of the GFR was not significantly different according to the presence of proteinuria (normal: −28.5±11.6% vs proteinuria: −28.7±15%; p=0.902); however, the postoperative hypertrophic FRV in the remnant kidney was significantly different (normal: 17.5±9.1% vs proteinuria: 13.8±14.1%; p=0.001). Meanwhile, the change in the percentage rate of the GFR/FRV was not significantly different (normal: 21.1±23% vs proteinuria: 23.8±28.3%; p=0.324). Multivariate logistic regression analysis revealed that age (p=0.010) and the GFR/FRV (p<0.001) were significant predictors of postoperative proteinuria.

Conclusion

Compensatory structural hypertrophy and functional hyperfiltration are positive adaptations that reduce the occurrence of proteinuria.

The Nephrologist's Management of Renal Cell Carcinoma After Kidney Surgery

Renal cell carcinoma is associated with chronic kidney disease as well as with common risk factors including hypertension and diabetes mellitus. Localized renal cell carcinoma is treated surgically and in these cases has a favorable prognosis. In particular, in those individuals with small renal masses (≤4 cm), preservation of kidney function should be prioritized. Postoperative chronic kidney disease or end-stage renal disease prevention should include baseline kidney function and risk factor assessment, nontumor renal biopsy, as well as counseling on treatment options to discuss maximizing kidney function preservation. Postnephrectomy prognosis can be determined with repeat laboratory and clinical assessment. Ultimately, early involvement of the nephrologist in a multidisciplinary team including the urology team will enable the reduction of postsurgical kidney disease related morbidity and potentially mortality.

CT Angiography Findings Predictive of Kidney Injury in Chronic Aortic Dissection

OBJECTIVE. The purpose of this study was to compare the volume alteration and effective renal plasma flow of kidneys supplied by false lumens (FLs) with those of kidneys supplied by true lumens (TLs), to show the discrepancy in perfusion between the two lumens. We sought to corroborate malperfusion of FL-supplied kidneys with imaging characteristics observed on CT angiography. MATERIALS AND METHODS. A retrospective analysis was conducted using prospectively collected data for 87 patients with a diagnosis of residual chronic aortic dissection between 2005 and 2013 who had one kidney perfused by a TL and the other kidney perfused by a FL. RESULTS. Overall, at follow-up, FL-supplied kidneys had a mean (± SD) effective renal plasma flow (117.5 ± 42.6 vs 146.6 ± 41.0 mL/min; p = 0.004) and volume (131.1 ± 37.1 vs 146.5 ± 33.3 cm³; p = 0.004) that were lower than those of TL-supplied kidneys. Multivariate analysis revealed the presence of a proximal major inlet (odds ratio, 0.306; 95% CI, 0.103-0.910; p = 0.033) and large FL area (odds ratio, 0.104; CI, 0.012-0.880; p = 0.038) as factors protecting against malperfusion of FL-supplied kidneys. In patients with dissected renal arteries, the FL-supplied kidney had low effective renal plasma flow (mean, 88.5 ± 26.8 vs 149.6 ± 43.5 mL/min; p = 0.004) and diminished volume (mean, 120.4 ± 30.4 vs 152.3 ± 24.6 cm³; p = 0.001). CONCLUSION. In the present study, kidneys perfused by FLs showed decreased volume and reduced effective renal plasma flow during follow-up, particularly those kidneys with dissected renal arteries, a small FL area at the renal level, and lack of a proximal major inlet. Further studies are warranted to identify the clinical relevance of malperfusion in FL-supplied kidneys.

Split renal function in patients with renal masses: utility of parenchymal volume analysis vs nuclear renal scans

OBJECTIVES

To evaluate the utility of parenchymal volume analysis (PVA) for estimation of split renal function (SRF) in patients with renal masses. SRF is important for deciding about partial vs radical nephrectomy (PN/RN) and assessing risk for developing severe chronic kidney disease after surgery. For renal donors PVA is routinely used to estimate SRF, but the utility of PVA for the more complex renal mass population remains undefined.

PATIENTS AND METHODS

All patients (n = 374) with renal tumours and a normal contralateral kidney managed with PN (2010-2018), with preoperative/postoperative nuclear renal scans (NRS) and cross-sectional imaging were analysed. Parenchymal volumes were measured by free-hand scripting or software analysis. Concordance between ipsilateral estimated glomerular filtration rate (eGFR) values based on SRF from NRS vs PVA were evaluated by Pearson correlation and Bland-Altman plots. Parallel analysis of all 155 patients managed with RN at our centre (2006-2016) with preoperative NRS and imaging was also performed.

RESULTS

For PN, the median age and tumour size were 62 years and 3.4 cm, respectively. The median preoperative ipsilateral parenchymal volume and eGFR were 181 cm³ and 36.9 mL/min/1.73 m² , respectively. Parenchymal volumes estimated by free-hand scripting vs software analyses correlated strongly (r = 0.98, P < 0.001). Preoperative ipsilateral eGFR based on SRF from PVA vs NRS also correlated strongly (r = 0.94, P < 0.001). Ipsilateral eGFR saved after PN correlated strongly with parenchymal volume preserved (all r >0.60); however, the correlation was much stronger when ipsilateral eGFRs were based on SRF from PVA rather than NRS (z-statistic = 3.15, P = 0.002). For RN patients, preoperative eGFR in the contralateral kidney based on SRF from PVA vs NRS also correlated strongly (r = 0.87, P < 0.001).

CONCLUSION

PVA has utility for estimation of SRF in patients with renal masses, even though this population is older and more comorbid than renal donors and the tumour can complicate the analysis. PVA can be obtained by software analysis from preoperative cross-sectional imaging and thus readily incorporated into routine clinical practice.

Acute gouty arthritis following percutaneous cryoablation of renal cell carcinoma

We report a case of acute gouty monoarthritis of the left ankle in a 58-year-old female with chronic renal insufficiency after cryoablation of a 3.8 cm left renal cell carcinoma. The patient's symptoms resolved after intravenous Solumedrol and did not recur at her 1-month follow-up visit. To the best of our knowledge, this is the first reported case of acute gouty monoarthritis after cryoablation of a renal cell carcinoma lesion in a patient with underlying chronic renal insufficiency. Clinicians should be vigilant of the potential for this complication in at-risk patient populations.

Outcome Measures Used to Report Kidney Function in Studies Investigating Surgical Management of Kidney Tumours: A Systematic Review

CONTEXT

Most practice decisions relevant to preserving kidney function in patients managed surgically for kidney tumours are driven by observational studies. A wide range of outcome measures are used in these studies, which reduces comparability and increases the risk of reporting bias.

OBJECTIVE

To comprehensively and succinctly describe the outcomes used to evaluate kidney function in studies evaluating surgical management of kidney tumours.

EVIDENCE ACQUISITION

Electronic search of the PubMed database was conducted to identify studies with at least one measure of kidney function in patients managed surgically for kidney tumours, published between January 2000 and September 2017. Abstracts were initially screened for eligibility. Full texts of articles were then evaluated in more detail for inclusion. A narrative synthesis of the evidence was conducted.

EVIDENCE SYNTHESIS

A total of 312 studies, involving 127905 participants, were included in this review. Most were retrospective (n=274) studies and conducted in a single centre (n=264). Overall, 78 unique outcome measures were identified, which were grouped into six outcome categories. Absolute postoperative kidney function (n=187), relative kidney function (n=181), and postoperative chronic kidney disease (n=131) were most frequently reported. Kidney function was predominantly quantified using estimated glomerular filtration rate or creatinine clearance (n=255), most using the modification of diet in renal disease equation (n=182). Only 70 studies provided rationale for specific outcome measures used.

CONCLUSIONS

There is significant variability in the reporting and quantification of kidney function in studies evaluating patients managed surgically for kidney tumours. A standardised approach to measuring and reporting kidney function will increase the effectiveness of outcomes reported and improve relevance of research findings within a clinical context.

PATIENT SUMMARY

Although we know that the removal of a kidney can reduce kidney function, clinical significance of various approaches is a matter of debate. This article demonstrates significant variability in the way kidney function was reported across all studies of patients with kidney cancer undergoing surgery, indicating a need for standardisation.

Estimated glomerular filtration rate's time to nadir after robot-assisted partial nephrectomy: Predictors and clinical significance on renal functional recovery

OBJECTIVES

To investigate the impact of postoperative time to nadir of estimated glomerular filtration rate on renal functional changes after robot-assisted partial nephrectomy.

METHODS

From 2006 to 2015, 287 patients with renal mass who underwent robot-assisted partial nephrectomy in a referral center were analyzed. The cohort was evaluated based on their time to develop nadir: group 1 (no nadir), group 2 (<48 h) and group 3 (≥48 h). The outcome measures were to evaluate the renal function recovery between groups, risk factors for development of nadir ≥48 h, as well as predictors of chronic kidney disease upstaging.

RESULTS

The mean estimated glomerular filtration rate percentage change was the worst in group 3 compared with groups 1 and 2, with 13.8%, -0.67% and 8%, respectively (P < 0.001). Chronic kidney disease upstaging was more common in group 3 compared with the other groups (P < 0.001). Age, tumor size, PADUA score and warm ischemia time were predictors of developing ≥48 h estimated glomerular filtration rate nadir (odds ratio 1.04, P = 0.002; odds ratio 1.43, P < 0.001; odds ratio 1.24, P = 0.018; odds ratio 1.05, P < 0.001), respectively. The 5-year probability of freedom from chronic kidney disease upstaging was lower in group 3 (75.6%) compared with the other groups - 88.1% and 100% (P = 0.003). Time to nadir ≥48 h was a predictor of chronic kidney disease upstaging (odds ratio 3.02, P = 0.022).

CONCLUSIONS

A continuous decline in estimated glomerular filtration rate (≥48 h) after partial nephrectomy is associated with increased risk of poor functional recovery overtime. Age, tumor size, PADUA score and warm ischemia time are independent predictors of developing ≥48 h time to nadir of estimated glomerular filtration rate. This higher risk subgroup should be targeted for stricter follow up to allow early detection of future risk of renal functional decline.

Long-Term Renal Function Recovery following Radical Nephrectomy for Kidney Cancer: Results from a Multicenter Confirmatory Study

PURPOSE

We sought to confirm the findings from a previous single institution study of 572 patients from Memorial Sloan Kettering Cancer Center in which we found that 49% of patients recovered to the preoperative estimated glomerular filtration rate within 2 years following radical nephrectomy for renal cell carcinoma.

MATERIALS AND METHODS

A multicenter retrospective study was performed in 1,928 patients using data contributed from 3 independent centers. The outcome of interest was postoperative recovery to the preoperative estimated glomerular filtration rate. Data were analyzed using cumulative incidence and competing risks regression with death from any cause treated as a competing event.

RESULTS

This study demonstrated that 45% of patients had recovered to the preoperative estimated glomerular filtration rate by 2 years following radical nephrectomy. Furthermore, this study confirmed that recovery of renal function differed according to preoperative renal function such that patients with a lower preoperative estimated glomerular filtration rate had an increased chance of recovery. This study also suggested that larger tumor size and female gender were significantly associated with an increased chance of renal function recovery.

CONCLUSIONS

In this multicenter retrospective study we confirmed that in the long term a large proportion of patients recover to preoperative renal function following radical nephrectomy for kidney tumors. Recovery is more likely among those with a lower preoperative estimated glomerular filtration rate.

Factors associated with acutely elevated serum creatinine following radical tumour nephrectomy: the Correlates of Kidney Dysfunction-Tumour Nephrectomy Database study

BACKGROUND

To identify factors associated with acutely elevated serum creatinine (SCr) within 7 days of radical tumour nephrectomy.

METHODS

The study population consisted of 130 consecutive patients managed for renal tumours. The primary outcome was acute kidney injury (AKI) (defined as SCr increase ≥50% above baseline), assessed using multivariable logistic regression analysis. The secondary outcome was SCr percentage increase, assessed using multivariable linear regression analysis.

RESULTS

Following nephrectomy, the mean percentage increase in SCr in the first week was 55%±29%, and 77 (59%) patients experienced AKI. Independent predictors of AKI post-nephrectomy were male gender [adjusted odds ratio (OR): 2.67; 95% confidence interval (95% CI): 1.01, 6.93], urine albumin-creatinine ratio (OR: 0.66; 95% CI: 0.47, 0.91), preoperative estimated glomerular filtration rate (eGFR) (OR: 1.03; 95% CI: 1.00, 1.05), laparoscopic nephrectomy (OR: 3.02; 95% CI: 1.00, 9.12), and non-clear cell renal cell carcinoma (RCC) (OR: 2.93; 95% CI: 1.04, 8.29). Independent predictors of a SCr increase were male gender (β: 12.0; 95% CI: 2.69, 21.3), urine albumin-creatinine ratio (β: -3.36; 95% CI: -6.55, -0.16), preoperative eGFR (β: 0.38; 95% CI: 0.10, 0.66), laparoscopic nephrectomy (β: 12.7; 95% CI: 1.05, 24.3) and obesity (β: 9.94, 95% CI: 0.61, 19.3).

CONCLUSIONS

Male gender, albuminuria, eGFR and laparoscopic nephrectomy independently associated with acutely elevated serum creatinine following radical tumour nephrectomy.

Compensatory Structural and Functional Adaptation After Nephrectomy in Obese Patients According to Waist Circumference

OBJECTIVE

To investigate whether the postnephrectomy renal adaptation mechanism, focused on functional hyperfiltration as well as structural hypertrophy, was affected by abdominal obesity.

MATERIALS AND METHODS

We retrospectively evaluated 358 patients who underwent simple or radical nephrectomy and nephroureterectomy between 2009 and 2013. Patients were classified according to waist circumference (WC), with values >102 cm in men and >88 cm in women considered high (obesity). Functional renal volume (FRV) was measured using computed tomography performed preoperatively and 6 months postoperatively to evaluate the degree of remnant kidney hypertrophy. The degree of hyperfiltration was calculated from the difference between the preoperative and postoperative glomerular filtration rate (GFR)/FRV.

RESULTS

The mean preoperative GFR, FRV, and GFR/FRV were 72.1 mL/min/1.73 m², 282.8 cm³, and 0.25 mL/min/1.73 m²/cm³, respectively. The percent GFR reduction was significantly greater in the high WC group (high, 25.9% vs normal, 16.0%, P = .036), although the degree of hypertrophic volume in the remnant kidney showed no difference. The change in GFR/FRV was statistically lower in the high WC group (high, 25.7% vs normal, 40.2%, P = .009). The factors associated with postoperative increased GFR/FRV were low preoperative GFR, proteinuria, high predictive preserved functional parenchymal volume ratio, absence of hypertension, increased levels of high-density lipoprotein cholesterol, and normal WC (all P < .05).

CONCLUSION

Patients with high WC might have a large reduction in postoperative renal function, owing to a lower degree of functional hyperfiltration.

Impact of ischaemia time on renal function after partial nephrectomy: a systematic review

OBJECTIVE

To assess the impact of ischaemia on renal function after partial nephrectomy (PN).

MATERIALS AND METHODS

A literature review was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. In January 2015, the Medline and Embase databases were systematically searched using the protocol ('warm ischemia'[mesh] OR 'warm ischemia'[ti]) AND ('nephrectomy'[mesh] OR 'partial nephrectomy'[ti]). An updated search was performed in December 2015. Only studies based on a solitary kidney model or on a two-kidney model but with assessment of split renal function were included in this review.

RESULTS

Of the 1119 studies identified, 969 abstracts were screened after duplicates were removed: 29 articles were finally included in this review, including nine studies that focused on patients with a solitary kidney. None of the nine studies adjusting for the amount of preserved parenchyma found a negative impact of warm ischaemia time on postoperative renal function, unless this was extended beyond a 25-min threshold. The quality and the quantity of preserved parenchyma appeared to be the main contributors to postoperative renal function.

CONCLUSION

Currently, no evidence supports that limited ischaemia time (i.e. ≤25 min) has a higher risk of reducing renal function after PN compared to a 'zero ischaemia' technique. Several recent studies have suggested that prolonged warm ischaemia (>25-30 min) could cause an irreversible ischaemic insult to the surgically treated kidney.

Factors Associated with Recovery of Renal Function following Radical Nephrectomy for Kidney Neoplasms

BACKGROUND AND OBJECTIVES

Partial nephrectomy or radical nephrectomy is the standard of care for patients with kidney neoplasms, but surgery may result in loss of renal function. We sought to identify patient characteristics associated with renal functional recovery following radical nephrectomy.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We performed a retrospective study among 572 patients with kidney neoplasms who underwent RN between 2006 and 2013. The primary endpoint was recovery of postoperative eGFR to the preoperative level. We plotted the trajectory of each patient's eGFR from their first postoperative visit up to 3 years after surgery. Cumulative incidence and competing risks regression estimated associations between patient and clinical characteristics and eGFR recovery, stratified by preoperative eGFR.

RESULTS

Median age was 61.5 years; 68% of patients were male, and 89% were white. Overall, eGFR increased over time following an initial postoperative decrease. Median postoperative follow-up among survivors was 10.8 (minimum, 0.03; maximum, 36.0) months; during follow-up, 263 patients achieved eGFR recovery. Median time to eGFR recovery was 25.3 months. Two-year cumulative incidence of eGFR recovery was 49% overall and 44% and 58% among those with preoperative eGFR≥60 and <60 ml/min per 1.73 m(2), respectively (P<0.001). On multivariable analysis, younger age at surgery and female sex were significantly associated with a higher chance of eGFR recovery among patients with preoperative eGFR<60 ml/min per 1.73 m(2). Among patients with preoperative eGFR≥60 ml/min per 1.73 m(2), hypertension was significantly associated with a lower chance of eGFR recovery, whereas increased tumor size was significantly associated with a higher chance of eGFR recovery.

CONCLUSIONS

Overall, almost half of the patients in this study recovered to their preoperative eGFR by 2 years following surgery. Distributions of preoperative risk factors differed by preoperative eGFR, leading to distinct factors that were significantly associated with chance of eGFR recovery.