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Introduction: Nephrologists have recently recognized the heterogeneity of kidney diseases among patients with diabetes and begun to actively perform percutaneous renal biopsies (PRBs). Nevertheless, the association between diabetes and major bleeding complications of PRB remains unclear. Methods: In this retrospective cohort study using the Diagnosis Procedure Combination database in Japan, we identified patients who underwent an elective PRB from July 2010 to March 2018. The primary outcome was the occurrence of major bleeding complications, defined as red blood cell transfusion within 7 days after PRB or invasive hemostasis after PRB. Multivariable regression analysis was performed to analyze the association between diabetes and major bleeding complications with adjustment for patient and hospital characteristics. Results: We identified 76,302 patients, including 8245 with diabetes. The proportion of PRBs performed for patients with diabetes continuously increased over time. Major bleeding complications occurred in 678 patients (0.9%), including 622 (0.8%) with red blood cell (RBC) transfusion and 109 (0.1%) with invasive hemostasis. Diabetes was significantly associated with major bleeding complications (relative risk [RR] = 2.41; 95% CI 2.00–2.90). Among patients with diabetes, multiagent or insulin treatment had significant association with major bleeding complications (RR = 1.57; 95% CI 1.18–2.10), compared with single-agent diabetes treatment. Conclusion: Diabetes is significantly associated with major bleeding complications of PRBs. Moreover, severity of diabetes has association with increases in major bleeding complications. Thus, nephrologists should carefully judge whether the anticipated benefits outweigh the relatively high risk of major bleeding complications when considering PRB for patients with diabetes.

BACKGROUND: The goal of the Artificial Intelligence in Renal Scarring (AIRS) study is to develop machine learning tools for noninvasive quantification of kidney fibrosis from imaging scans. METHODS: We conducted a retrospective analysis of patients who had one or more abdominal computed tomography (CT) scans within 6 months of a kidney biopsy. The final cohort encompassed 152 CT scans from 92 patients, which included images of 300 native kidneys and 76 transplant kidneys. Two different convolutional neural networks (slice-level and voxel-level classifiers) were tested to differentiate severe versus mild/moderate kidney fibrosis (≥50% versus

BACKGROUND Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can result in clinically significant multi-system disease including involvement in the kidney. The underlying histopathological processes were unknown at the start of the pandemic. As case reports and series have been published describing the underlying renal histopathology from kidney biopsies, we have started to gain an insight into the renal manifestations of this novel disease. AIM To provide an overview of the current literature on the renal histopathological features and mechanistic insights described in association with coronavirus disease 2019 (COVID-19) infection. METHODS A systematic review was performed by conducting a literature search in the following websites-‘PubMed’, ‘Web of Science’, ‘Embase’ and ‘Medline-ProQuest’ with the following search terms-“COVID-19 AND kidney biopsy”, “COVID-19 AND renal biopsy”, “SARS-CoV-2 AND kidney biopsy” and “SARS-CoV-2 AND renal biopsy”. We have included published data up until February 15, 2021, which includes kidney biopsies (native, transplant and postmortem) from patients with COVID-19. Data on clinical presentation, histopathological features, management and outcome was extracted from the reported studies. RESULTS The total number of biopsies reported on here is 288, of which 189 are postmortem, 84 native and 15 transplants. The results are varied and show underlying pathologies ranging from collapsing glomerulopathy and acute tubular injury (ATI) to anti-nuclear cytoplasmic antibody associated vasculitis and pigment nephropathy. There was variation in the specific treatment used for the various renal conditions, which included steroids, hydroxychloroquine, eculizumab, convalescent plasma, rituximab, anakinra, cyclophosphamide and renal replacement therapy, amongst others. The pathological process which occurs in the kidney following COVID-19 infection and leads to the described biopsy findings has been hypothesized in some conditions but not others (for example, sepsis related hypoperfusion for ATI). It is important to note that this represents a very small minority of the total number of cases of COVID-19 related kidney disease, and as such there may be inherent selection bias in the results described. Further work will be required to determine the pathogenetic link, if any, between COVID-19 and the other renal pathologies. CONCLUSION This report has clinical relevance as certain renal pathologies have specific management, with the implication that kidney biopsy in the setting of renal disease and COVID-19 should be an early consideration, dependent upon the clinical presentation.

Ipilimumab is a human monoclonal antibody targeting cytotoxic T-lymphocyte-associated protein 4 approved for the treatment of non-small-cell lung cancer (NSCLC) and other malignancies. Despite a high prevalence of other immune-related adverse events (irAEs), checkpoint inhibitor (CPI)-related nephrotoxicity has been reported less frequently. In this clinical case report, we describe the evaluation of a 70-year-old female with stage IV NSCLC who presented with nephrotic range proteinuria 4 weeks after receiving her first cycle of ipilimumab. She underwent a renal biopsy and was found to have IgA nephropathy that was presumed to be secondary to ipilimumab use, given recent initiation of therapy and clinical history. Unfortunately, despite prompt initiation of corticosteroids, her acute kidney injury progressed and she required hemodialysis, later transitioning to hospice. To our knowledge, this is one of few reported cases of IgA nephropathy secondary to CPI use. With increasing use of CPIs, this case further emphasizes the need for continued surveillance for irAEs, which can occur at any point in a patient’s treatment course.

Rationale & Objective Although kidney biopsy is a useful tool, nephrologists’ approach toward biopsies is inconsistent for reasons incompletely understood, including lack of established clinical guidelines. We examined contemporary clinical decision-making patterns among nephrologists to perform native kidney biopsy. Study Design Qualitative study using semistructured interviews. Setting & Participants Purposive sampling was used to select nephrologists from different regions in the United States. Semistructured interviews were continued until thematic saturation. Analytical Approach A modified grounded theory was used to identify dominant themes reflecting the nephrologists’ decision-making styles about kidney biopsy. Results Twenty nephrologists were interviewed: 16 (80%) were from academic centers, 3 (15%) performed their own biopsies, and 7 (35%) had been in practice for less than 10 years. The median time of practice was 14 years. We found substantial variability among the nephrologists in their attitude toward using kidney biopsy, which reflected individual differences in weighing the risks and benefits of the procedure for an individual patient. Five overarching themes were identified: operator comfort with biopsy and availability of interventional radiologist, exposure to biopsy during training and years of experience, concerns about the invasiveness of biopsy and inflicting harm, perception of evidence base and limited treatment options, and patient characteristics and preference. Limitations Generalizability was limited because the nephrologists sampled may not have been broadly representative. Conclusions Multiple factors influence nephrologists’ decision to pursue kidney biopsy, with substantial variability among nephrologists that can have meaningful clinical implications. This suggests the need to establish consensus guidelines to make biopsy practice more standardized., Kidney biopsy is the gold standard for diagnosis of most kidney diseases, but practice patterns vary widely, and no consensus guidelines exist. Studies are lacking on how nephrologists go about deciding which patients to biopsy with acute or chronic kidney disease. To address this gap in the literature, we conducted a qualitative study amongst nephrologists to examine and understand the reasons for variabilities in practice patterns. We found that the biopsy decision is complex and that multiple factors inform the decision to biopsy including nephrologist’s experience with the biopsy procedure, nephrologists’ varying perspectives on indications, the ease of scheduling biopsies, and patient preference. Development of consensus guidelines may assist nephrologists in making complex clinical decisions that balance risks and benefits.

The authors report a case of a 57-year-old woman who was successfully treated with a percutaneous embolization procedure for a renal arteriovenous fistula that developed as a complication of a kidney biopsy. An acute kidney injury that failed to resolve with medical management prompted further investigation with a renal biopsy. Five hours after the kidney biopsy, the patient became hemodynamically unstable with a blood pressure of 77 of 52 mm Hg. A stat abdominal computed tomography scan without contrast discovered a large left-sided perinephric hematoma that measured up to 11.5 cm with a moderate amount of perinephric blood. An angiogram subsequently demonstrated the presence of an arteriovenous fistula at the inferior pole of the left kidney. Several 2 × 3 mm and 3 × 3 mm coils were deployed into two separate segmental branches of the inferior pole, and the post embolization angiogram confirmed resolution of the previously visualized arteriovenous fistula.

A 67-year-old female with Type 2 diabetes mellitus developed nephrotic syndrome within 1 week of receiving the first dose of severe acute respiratory syndrome coronavirus 2 CoronaVac vaccine. A kidney biopsy was consistent with minimal change nephrotic syndrome and treatment was symptomatic with antiproteinuric therapy and improvement in proteinuria. Oedema returned within 1 week of the second dose of CoronaVac. On this occasion, acute kidney injury and massive proteinuria were noted. In kidney biopsy, glomeruli were normal, but tubulointerstitial inflammation consistent with acute tubulointerstitial nephritis was noted. Pulse followed by oral steroids was followed by recovery of kidney function. Proteinuria decreased after initiation of cyclosporine A.

Background Percutaneous kidney biopsy is the gold standard investigation for the diagnosis of kidney diseases. The associated risks of the procedure depend on the skill and experience of the proceduralist as well as the characteristics of the patient. The Kidney Health Australia – Caring for Australasians with Renal Impairment (KHA-CARI) guidelines on kidney biopsies, published in 2019, are the only published national kidney biopsy guidelines. As such, this study surveys current kidney biopsy practices in Australasia and examines how they align with the Australian guidelines, as well as international biopsy practice. Methods A cross-sectional, multiple-choice questionnaire was developed examining precautions prior to kidney biopsy; rationalisation of medications prior to kidney biopsy; technical aspects of kidney biopsy; complications of kidney biopsy; and indications for kidney biopsy. This was distributed to all members of the Australian and New Zealand Society of Nephrology (ANZSN). Results The response rate for this survey is approximately 21.4 % (182/850). Respondents found agreement (> 75.0 %) in only six out of the twelve questions (50.0 %) which assessed their practice against the KHA-CARI guidelines. Conclusions This is the first study of its kind where kidney biopsy practices are examined against a clinical guideline. Furthermore, responses showed that practices were incongruent with guidelines and that there was a lack of consensus on many issues.

Background Histological findings of kidney involvement have been rarely reported in pediatric patients with SARS-CoV-2 infection. Here, we describe clinical, laboratory, and histological findings of two pediatric cases with almost exclusive kidney involvement by SARS-CoV-2. Results A 10-year-old girl with IgA vasculitis nephritis underwent kidney biopsy, showing diffuse and segmental mesangial-proliferative glomerulonephritis, and steroid therapy was initiated. After the worsening of the clinical picture, including an atypical skin rash, she was diagnosed with SARS-CoV-2. The re-evaluation of initial biopsy showed cytoplasmatic blebs and virus-like particles in tubular cells at electron microscopy. Despite SARS-CoV-2 clearance and the intensification of immunosuppression, no improvement was observed. A second kidney biopsy showed a crescentic glomerulonephritis with sclerosis, while virus-like particles were no longer evident. The second patient was a 12-year-old girl with a 3-week history of weakness and weight loss. Rhinitis was reported the month before. No medications were being taken. Blood and urine analysis revealed elevated serum creatinine, hypouricemia, low molecular weight proteinuria, and glycosuria. A high SARS-CoV-2-IgG titre was detected. Kidney biopsy showed acute tubular-interstitial nephritis. Steroid therapy was started with a complete resolution of kidney involvement. Conclusion We can speculate that in both cases SARS-CoV-2 played a major role as inflammatory trigger of the kidney damage. Therefore, we suggest investigating the potential kidney damage by SARS-CoV-2 in children. Moreover, SARS-CoV-2 can be included among infectious agents responsible for pediatric acute tubular interstitial nephritis.

Anti-brush border antibody (ABBA) disease, also called anti–low-density lipoprotein receptor-related protein 2 (anti-LRP2) nephropathy, occurs due to the formation of antibodies against brush border antigens of the renal proximal convoluted tubule. We report a case of ABBA disease in a male farmer in his 30s who presented with 2 years of polyuria, dysuria, nocturia, and urinary urgency. He described a history of long-term occupational exposure to pesticides and silica, evolving into possible pneumoconiosis, and prior pulmonary tuberculosis. At presentation, he had reduced kidney function (serum creatinine 3.6 mg/dL) with hyponatremia, hypokalemia, hypophosphatemia, a normal anion gap, metabolic acidosis, and respiratory acidosis, and 2.2 g/day of urine proteinuria. The kidney biopsy was consistent with ABBA, showing amorphous immune-deposits in the tubular basement membrane and strong positivity on indirect immunofluorescence in the brush border of the proximal tubules. The trigger for production of ABBA is still unknown, but it may be associated with chronic conditions such as pulmonary tuberculosis and occupational exposures such as silica and pesticides, as seen in the patient in this report. Most cases do not respond to immunosuppression, and the prognosis is poor.

Zi-Shan Lin,1,* Xiao-Juan Yu,1,* Xu Zhang,1,2 Su-Xia Wang,1,2 Xi-Nan Cen,3 Fu-De Zhou,1 Ming-Hui Zhao1,4 1Renal Division, Department of Medicine, Peking University First Hospital; Institute of Nephrology, Peking University, Renal Pathology Center, Institute of Nephrology, Peking University, Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of CKD Prevention and Treatment, Ministry of Education of China, Beijing, People’s Republic of China; 2Laboratory of Electron Microscopy, Pathological Centre, Peking University First Hospital, Beijing, People’s Republic of China; 3Department of Hematology, Peking University First Hospital, Beijing, People’s Republic of China; 4Peking-Tsinghua Center for Life Sciences, Beijing, People’s Republic of China*These authors contributed equally to this workCorrespondence: Fu-De ZhouRenal Division, Department of Medicine, Peking University First Hospital, Institute of Nephrology, Peking University; Renal Pathology Center, Institute of Nephrology, Peking University, Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of CKD Prevention and Treatment, Ministry of Education of China, No. 8 Xishiku Street, Xicheng District, Beijing, 100034, People’s Republic of ChinaTel +86-13501162527Fax +86-10-83575694Email zhoufude1801@vip.sina.comBackground: Monoclonal immunoglobulin-associated renal lesions in patients with newly diagnosed myeloma vary. We aimed to determine the pathological spectrum and analyze associated prognostic factors.Methods: Fifty-six patients with newly diagnosed multiple myeloma and biopsy-proven renal lesions were enrolled. Kidney biopsies were reanalyzed, and the baseline clinical characteristics, treatments and outcomes were recorded.Results: Fifty-one patients had monoclonal immunoglobulin-associated renal lesions, with myeloma cast nephropathy (MCN) being the most common pattern. We divided our cohort into pure MCN, MCN+ other pathologies and non-MCN. Patients with MCN had more severe renal injury than those with non-MCN. In our cohort, none of the patients with pure MCN or MCN + other pathologies presented with nephrotic syndrome. Patients with non-MCN had better renal and overall survival than those with pure MCN but similar survivals to those with MCN + other pathologies. Number of myeloma casts (HR 1.08, p = 0.012) was the only independent prognostic factor for renal survival. Male sex (HR: 3.64; p = 0.015) and number of casts (HR: 1.17; p = 0.001) were independent prognostic factors for overall survival.Conclusion: Patients with MCN had more severe renal injury than those with non-MCN. Patients with non-MCN had better renal and overall outcomes than those with pure MCN, but their outcomes were similar to those with MCN + other pathologies. The independent predictors of overall survival were male sex and number of myeloma casts.Keywords: kidney biopsy, multiple myeloma, myeloma cast nephropathy, monoclonal immunoglobulin, prognosis

TAFRO (thrombocytopenia, anasarca, fever, reticulin myelofibrosis/renal insufficiency, and organomegaly) syndrome is a systemic inflammatory disease sharing some features with Castleman disease and POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, and skin changes) syndrome in relation to abnormal secretions of interleukin 6 and vascular endothelial growth factor. The kidney is a main target organ of TAFRO syndrome but the kidney histopathology associated with TAFRO syndrome is yet to be completely defined. We report 3 TAFRO syndrome cases with different clinical courses in which kidney biopsies were performed. In all 3 cases, kidney biopsies showed similar glomerular lesions of diffuse global swelling of the endothelium and expansion of subendothelial spaces, consistent with severe glomerular endothelial injury. Case 3 showed an additional finding of focal tubulointerstitial injury characterized by marked plasma cell infiltration, which was absent in the other 2 cases. Clinical symptoms in cases 1 and 2, which had lower disease severity scores of TAFRO syndrome, were effectively treated with the administration of corticosteroids or a combination of corticosteroids and cyclosporine A. Case 3, with a higher disease severity score, had an aggressive clinical course that was refractory to corticosteroids and tocilizumab; the patient ultimately died of multiple organ failure. In all 3 cases, kidney biopsy provided indications for the diagnosis process and clinical management of TAFRO syndrome.

Introduction d-Serine, present only in trace amounts in humans, is now recognized as a biomarker of chronic kidney disease (CKD). CKD is heterogeneous in its original kidney diseases, whose diagnoses require kidney biopsy. In this study, we examined whether the intra-body dynamics of d-serine, indexed by its blood and urinary levels, reflects the origin of kidney diseases. Methods Patients with six kinds of kidney disease undergoing kidney biopsy were enrolled in a single center. Levels of d- and l-serine were measured using two-dimensional high-performance liquid chromatography. The associations between the origin of kidney diseases and the intra-body dynamics of d-serine were examined using multivariate cluster analyses. Results Unlike the non-CKD profile, patients with CKD showed broadly-distributed profiles of intra-body dynamics of d-serine. The plasma level of d-serine plays a key role in the detection of kidney diseases, whereas a combination of plasma and urinary levels of d-serine distinguished the origin of CKD, especially lupus nephritis. Conclusion Intra-body dynamics of d-serine have the potential to predict the origin of kidney diseases. Monitoring of d-serine may guide specific treatments for the origin of kidney diseases.

Background Soluble tumor necrosis factor receptor (sTNFR)-1, sTNFR-2, YKL-40, monocyte chemoattractant protein (MCP)-1, and soluble urokinase plasminogen activator receptor (suPAR) have emerged as promising biomarkers of inflammation but have not been evaluated across diverse types of kidney diseases. Methods We measured these plasma biomarkers in 523 individuals enrolled into a prospective, observational cohort study of patients undergoing clinically indicated native kidney biopsy at 3 tertiary care hospitals. Two kidney pathologists adjudicated biopsy specimens for semiquantitative scores of histopathology. Proportional hazard models tested associations between biomarkers and risks of kidney disease progression (composite of ≥40% estimated glomerular filtration rate [eGFR] decline or end-stage kidney disease [ESKD]) and death. Results Mean eGFR was 56.4±36 ml/min per 1.73 m2 and the median proteinuria (interquartile range) was 1.6 (0.4, 3.9) g/g creatinine. The most common primary clinicopathologic diagnoses were proliferative glomerulonephritis (29.2%), nonproliferative glomerulopathy (18.1%), advanced glomerulosclerosis (11.3%), and diabetic kidney disease (11.1%). sTNFR-1, sTNFR-2, MCP-1, and suPAR were associated with tubulointerstitial and glomerular lesions. YKL-40 was not associated with any histopathologic lesions after multivariable adjustment. During a median follow-up of 65 months, 182 participants suffered kidney disease progression and 85 participants died. After multivariable adjustment, each doubling of sTNFR-1, sTNFR-2, YKL-40, and MCP-1 was associated with increased risks of kidney disease progression, with hazard ratios ranging from 1.21 to 1.47. Each doubling of sTNFR-2, YKL-40, and MCP-1 was associated with increased risks of death, with hazard ratios ranging from 1.33 to 1.45. suPAR was not significantly associated with kidney disease progression or death. Conclusions sTNFR-1, sTNFR-2, YKL-40, MCP-1, and suPAR are associated with underlying histopathologic lesions and adverse clinical outcomes across a diverse set of kidney diseases., Graphical abstract

Late-onset retroperitoneal hemorrhage from renal intraparenchymal pseudoaneurysm (RIP) following a kidney biopsy is an extremely rare complication but should not be ignored, especially in high-risk populations. Here, we introduce a 32-year-old Caucasian female who presented with sudden-onset left-sided flank pain. She had recently been diagnosed with systemic lupus erythematosus (SLE) and had undergone a computed tomography (CT)-guided core needle biopsy of the left kidney 9 days earlier. The results were consistent with lupus nephritis class III or IV. Initial vitals were within normal limits. She appeared pale and her left flank was tender to palpation without discoloration or abdominal distention. Laboratory investigations showed a hemoglobin level of 7.1 g/dL. The CT scan of the abdomen and pelvis revealed a large hyperdense left perinephric collection consistent with perinephric hematoma with a moderate amount of retroperitoneal stranding most prominent on the left side extending across the midline to the right side. Contrast extravasation was suspected in the lower pole of the left kidney consistent with active bleeding site. Emergent renal angiography revealed a 2 × 1 cm intraparenchymal pseudoaneurysm in the lower pole of the left kidney along with a few small microaneurysms. Coil embolization of the pseudoaneurysm was successfully performed without any complications. In conclusion, SLE or lupus nephritis in this patient may be the predisposing factors for microaneurysm and RIP formations. RIP is an unusual complication after percutaneous kidney biopsy that carries a significant mortality rate if ruptured, causing retroperitoneal hemorrhage. Clinicians should be vigilant when encountering high-risk patients with persistent hematuria, flank pain, or abdominal pain within four weeks after a kidney biopsy.

Introduction Kidney biopsy is an important tool for making diagnoses and for assessing the drug treatment requirements and disease prognosis in the management of kidney diseases. There are variations in the rate of complications associated with kidney biopsies across countries, and this depends on various clinical and technical factors. The aim of this study is to report on complications associated with kidney biopsy performed in low- and middle-income countries. Methods Two reviewers searched studies in MEDLINE, Embase, Cochrane Reviews, and African Journals Online. A random effects meta-analysis method was used to pool estimates of complications. Results We identified 39 studies reporting on 19,500 kidney biopsies with overall complications (major + minor) rate of 14.9% (95% confidence interval = 11.4%–18.7%). Fewer complications were reported in biopsies performed with real-time ultrasound scans compared to those pre-marked using ultrasound or blind procedures (12.4% vs. 14.9% vs. 24.5%; P = 0.037), respectively. Complications, albeit lower for procedures performed with automated needles (13.3%), were not significantly different from those performed with nonautomated needles (17.3%; P = 0.588). Major complications included macroscopic hematuria (1.48%), nephrectomy (0.04%), blood loss requiring red cell transfusion (0.24%), angiographic intervention (0.22%), and death (0.01%). Conclusion Complications associated with kidney biopsy in low- and middle-income countries are low, are comparable to those in other settings, and occur more sparingly when real-time ultrasound techniques or automated kidney biopsy needles are used. This suggests the need to expand the use of this procedure to improve diagnosis of kidney pathologies and choice of therapy when indicated., Graphical abstract

Introduction: Kidney biopsies (KBs) are performed in patients with type 2 diabetes (T2D) to diagnose non-diabetic or hypertensive kidney disease (NDHKD) potentially requiring specific management compared to diabetic and or hypertensive nephropathy (absence of NDHKD). Indications for KB are based on the presence of atypical features compared to the typical course of diabetic nephropathy. In this study, we assessed the association of different patterns of atypical features, or KB indications, with NDHKD. Methods: Native KBs performed in patients with T2D were analyzed. Data were collected from the patients’ records. KB indications were determined according to the presence of different atypical features considered sequentially: (1) presence of any feature suggesting NDHKD which is not among the following ones, (2) recent onset of nephrotic syndrome, (3) low or rapidly declining estimated glomerular filtration rate (eGFR), (4) rapid increase in proteinuria, (5) short duration of diabetes, (6) presence of hematuria, or (7) normal retinal examination. Results: Among the 463 KBs analyzed, NDHKD was diagnosed in 40% of the total population and 54, 40, 24, and 7% of the KBs performed for indications 1–4 respectively. Conversely, no patient who underwent KB for indications 5–7 displayed NDHKD. Logistic regression analyses identified eGFRCKD-EPI >15 mL/min/1.73 m2, urinary protein-to-Cr ratio

BACKGROUND AND OBJECTIVES: ANCA-associated GN is a common cause of rapidly progressive GN, with high relapse rates. The early recognition of an ANCA-associated GN relapse is of importance to prevent loss of kidney function. Urinary soluble CD163 has been identified as a promising marker of active ANCA-associated GN. Previous studies, however, are limited by the lack of histologic data. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We analyzed urinary soluble CD163 in 95 patients with ANCA-associated vasculitis who underwent a kidney biopsy. In total, 125 kidney tissue sections (first kidney biopsy, n=67; repeated biopsy, n=58) with concurrent 24-hour urine samples were studied. Correlation analyses comparing urinary soluble CD163 levels and morphologic features of ANCA-associated GN were performed using Spearman rank correlation analysis. The diagnostic performance of biomarkers to detect relapsing ANCA-associated GN was evaluated using receiver operating characteristics curve analysis. RESULTS: High levels of urinary soluble CD163 were found in 96 (87%) of 110 biopsies with active ANCA-associated GN compared with one (7%) of 15 biopsies without active ANCA-associated GN and one (6%) of 17 healthy controls. Urinary soluble CD163 correlated with fibrinoid necrosis (Rho=0.48, P

Aim: Kidney biopsy is crucial in management of renal diseases. Biopsies in children have added difficulties. The aim of this study is to investigate our 5-year experience of real-time ultrasound (USG)-guided percutaneous renal biopsy (PRB). Methods: Institutional database of children who underwent PRB in a tertiary hospital between January 2015 and March 2020 were evaluated retrospectively. A single pediatric nephrologist performed all the biopsies using an automated spring-loaded biopsy gun under real-time USG guidance. Results: Thirty-two biopsies were performed in 17 males (53.1%) and 15 females (46.9%), and the median age of the children was 14.5 years. The most common indication for biopsy was nephrotic syndrome in 13 /32 children (40.6%). Median number of glomeruli obtained from biopsy specimens was 18 (min-max=7-54 glomeruli). A diagnosis was achieved in all cases (100%) by a histopathologist. The only complication observed in a 16-year-old boy was a self-limited gross hematuria (3.1%) episode with subcapsular hematoma.Conclusion: Real-time USG-guided PRB with an automated biopsy gun is an effective and safe technique, providing superior yield when performed by a pediatric nephrologist. Performing kidney biopsy is an essential tool in a nephrologist’s workshop., Amaç: Böbrek biyopsisinin böbrek hastalıklarının yönetiminde oldukça önemli bir yeri vardır. Özellikle çocuklarda yapılan biyopsiler ek zorluklar gösterir. Bu çalışmanın amacı, çocuklarda uygulamış olduğumuz beş yıllık ultrasonografi eşliğinde perkutan böbrek biyopsisi (PRB) deneyimimizi değerlendirmektir.Yöntemler: Ocak 2015- Mart 2020 arasında bir üçüncü basamak hastanesinde PRB uygulanan çocukların hastane kayıtları geriye dönük olarak irdelenmiştir. Tüm biyopsiler, eş zamanlı USG altında tek bir çocuk nefroloğu tarafından otomatik biyopsi tabancası kullanılarak uygulanmıştır.Bulgular: Medyan yaşı 14,5 yaş olmak üzere; 17 erkek (%53,1) ve 15 kız çocuğuna (%46,9) 32 böbrek biyopsisi uygulandı. En sık biyopsi endikasyonu, çocukların 13/32’sinde (%40,6) nefrotik sendrom idi. Biyopsi örneklerinden alınan medyan glomerül sayısı 18 (min-max=7-54 glomerül) idi. Histopatolog tarafından tüm olgularda (%100) tanı konulabildi. Gözlenen tek komplikasyon, 16 yaşındaki bir erkek çocuğunda subkapsüler hematomla birlikte kendiliğinden düzelen gross hematüri süreci idi (%3,1).Sonuç: Çocuklarda; PRB Bir çocuk nefroloğu tarafından otomatik biyopsi tabancası kullanılarak, eş-zamanlı USG altında yapıldığında, yeterince fazla örneğin alınmasını sağlayan, etkili ve güvenli bir tekniktir. Böbrek biyopsisi, bir nefroloğun çalışma sorumluluğunda yapması gereken önemli bir uygulamadır.

Background Fatty acid-binding protein 4 (FABP4), but not FABP1 (liver-type FABP), is ectopically induced in injured glomerular endothelial cells, and urinary FABP4 (U-FABP4) level is associated with proteinuria and renal dysfunction in a general population. Methods The clinical significance of U-FABP4 was investigated in 81 patients (male/female: 43/38, age: 57 ± 17 years) who underwent kidney biopsy. Results U-FABP4 was negatively correlated with estimated glomerular filtration rate (eGFR) (r = − 0.56, P r = 0.58, P r = 0.52, P < 0.01). Multivariable regression analysis showed that eGFR, proteinuria and U-FABP1 were independent predictors of U-FABP4. The level of U-FABP4, but not that of proteinuria, eGFR or U-FABP1, in minimal change nephrotic syndrome (MCNS) was significantly lower than the level in membranous nephropathy (MN) and that in diabetic nephropathy. Receiver operating characteristic curve analysis indicated that U-FABP4 level ≤ 0.78 μg/gCr predicted MCNS in patients who had nephrotic-range proteinuria with a high level of accuracy. When divided by the median value of U-FABP4 at baseline in 33 of the 81 patients who could be followed up, the yearly change (post–pre) in eGFR in the low U-FABP4 group was significantly greater than that in the high U-FABP4 group (median: 11.0 vs. -5.0 mL/min/1.73m2/year). Conclusions U-FABP4 level is independently associated with proteinuria and renal dysfunction in patients with glomerular kidney disease. A low U-FABP4 level may predict MCNS in patients with nephrotic syndrome and would be a useful biomarker for differential diagnosis of MCNS and MN, which are common causes of nephrotic syndrome.

Over the past 2 decades, scoring systems for multiple glomerular diseases have emerged, as have consortia of pathologists and nephrologists for the study of glomerular diseases, including correlation of pathologic findings with clinical features and outcomes. However, one important limitation faced by members of these consortia and other renal pathologists and nephrologists in both investigative work and routine practice remains a lack of uniformity and precision in clearly defining the morphologic lesions on which the scoring systems are based. In response to this issue, the Renal Pathology Society organized a working group to identify the most frequently identified glomerular lesions observed by light microscopy and electron microscopy, review the literature to capture the published definitions most often used for each, and determine consensus terms and definitions for each lesion in a series of online and in-person meetings. The defined lesions or abnormal findings are not specific for any individual disease or subset of diseases, but rather can be applied across the full spectrum of glomerular diseases and within the context of the different scoring systems used for evaluating and reporting these diseases. In addition to facilitating glomerular disease research, standardized terms and definitions should help harmonize reporting of medical kidney diseases worldwide and lead to more-precise diagnoses and improved patient care.

Introduction South Africa has the highest prevalence of HIV in the world. The epidemiology of kidney disease among people with HIV infections is well-described in the United States. However, there are limited data coming from South Africa, particularly that involve kidney biopsies. The purpose of this study was to determine what, if any, patient factors are predictive of HIV-associated nephropathy (HIVAN) on kidney biopsy in a South African kidney biopsy cohort. Methods This study prospectively collected data of all patients infected with HIV referred to the Groote Schuur Hospital (GSH) renal unit for a kidney biopsy from 2002 to 2018. Results There were 419 patients included in the study. Mean age was 36.5 years (SD, 9.4); 219 (52.3%) were women; and all were black. Seventy-nine patients (18.9%) were on dialysis at the time of biopsy; the mean estimated glomerular filtration rate among the remainder was 41.4 ml/min per 1.73 m2 (SD, 39.2). Only 163 patients (47.1%) were known to be taking antiretroviral therapy (ART) at the time of biopsy. There were 246 (58.7%) cases of HIVAN detected, and they were comparable on age, sex, kidney function, and kidney size to those with kidney disease of other causes but were less likely to be taking ART (P < 0.001). Biopsy confirmed HIVAN was associated with mortality (adjusted hazard ratio, 1.77; 95% confidence interval [CI]: 1.07–2.91; P = 0.025), and the use of ART at biopsy was protective (adjusted hazard ratio, 0.52; 95% CI, 0.32–0.84, P = 0.008). The proportion of HIVAN on biopsy decreased and the proportion taking ART increased from 2002 to 2018 (P for trend for both < 0.001). Conclusion In summary, HIVAN was the most common etiology of kidney disease in this biopsy cohort from South Africa; however, the proportion with biopsy-proven HIVAN declined over time, perhaps in the setting of greater ART availability., Graphical abstract

Lymphomatous infiltration of kidney parenchyma is a frequent complication of systemic hematologic malignancies and often shows subtle clinical presentation. Diffuse large B-cell lymphoma represents the most frequent form involving the kidney, with advanced stage at diagnosis, poor outcome, and risk for central nervous system relapse if not adequately treated. Kidney biopsy can provide specific and early detection of these cases, helping in the differential diagnosis with more frequent entities. Finally, further hematologic workup (bone marrow biopsy, complete blood cell count, and positron emission tomography) can distinguish secondary involvement of the kidney from the rarer kidney-limited forms, especially in patients without a previous diagnosis of lymphoma. Making a prompt and correct diagnosis directs the management of these cases and may improve the outcome, as described in the present report.

Acute kidney injury (AKI) is a common presentation which can result from a number of different underlying pathological processes. Haematological malignancies, particularly multiple myeloma (MM), are known to frequently present with AKI. Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a rare condition which can cause crescentic glomerulonephritis (GN), resulting in AKI. We present the case of a 60-year-old man who presented with clinical features suggestive of AAV in the context of blood tests which demonstrated AKI and positive perinuclear ANCA (p-ANCA) and anti-myeloperoxidase (anti-MPO) titres. Further investigations demonstrated an underlying diagnosis of MM. A renal biopsy was ultimately required to determine the cause of AKI, a cast nephropathy. This case is the first to our knowledge which demonstrates a rare situation in which myeloma kidney is associated with positive p-ANCA and anti-MPO titres, without any evidence of a crescentic GN. It highlights the importance of following up on all investigations sent in the context of AKI, even when a potential diagnosis seems evident. Furthermore, it demonstrates the role of renal biopsy in confirming a diagnosis in the context of AKI with multiple differential diagnoses.

The pathogenetic relationship of kidney damage and an aberrant clone of the B-cell line producing nephrotoxic monoclonal immunoglobulin underlies the concept of “monoclonal gammopathy of renal significance” (MGRS). Herein the aberrant clone does not reach the criteria necessary for initiating antitumor therapy according to oncohematological indications. MGRS is a new nosology in modern nephrology and oncohematology. Monoclonal protein’s pathological effects on kidney parenchyma result in irreversible decline of kidney function till the end stage renal disease that in line with the position of International Consensus of hematologists and nephrologists determinates critical necessity for clone specific treatment in patients with MGRS despite the absence of hematological indications for treatment initiation. Main challenge of MGRS in Russian Federation is an inaccessibility of an in-time diagnostic and appropriate treatment for the great majority of patients due to the following reasons: i) limited knowledge about the MGRS among hematologists and nephrologists; ii) lack of necessary diagnostic resources in most health-care facilities; iii) lack of approved clinical recommendations and medical economic standards for treatment of this pathological entity. In order to overcome these limitations, leading oncohematologists and nephrologists of the Russian Federation on behalf of professional communities at the end of 2019 published a conciliation document: “Monoclonal gammopathy of renal significance: Consensus of hematologists and nephrologists of Russia on the establishment of nosology, diagnostic approach and rationale for clone specific treatment”. Consensus document comprises the opinion of experts – leading nephrologists and hematologists of Russian Federation – on the problem of MGRS including the incoherence in nosology classification, diagnostics approach and rationale for clone specific treatment. Consensus document is based on conclusions and agreements reached during the conference of leading nephrologists and hematologists of Russia which was held in the framework of symposia “Plasma cell dyscrasias and lymphoproliferative diseases: modern approaches to therapy”, 15–16 of March 2019, Pavlov First Saint Petersburg State Medical University, Saint Petersburg, Russia. Consensus is intended to define the principal practical steps to resolve the problem of MGRS in Russian Federation that are summarized as final clauses which we present here.

Rationale & Objective Anorexia nervosa is often intractable and induces various physical disorders, including kidney disease and mineral disorders, occasionally progressing to kidney failure. No consensus-based clinical practice guidelines have been established for patients with anorexia nervosa referred to a nephrologist. Study Design Patients with anorexia nervosa–associated kidney disease diagnosed were analyzed retrospectively. Kidney outcomes were defined as doubling of serum creatinine level and/or progression to end-stage kidney disease. Setting & Participants Patients with a history of anorexia nervosa with kidney disease, including electrolyte abnormalities, who were referred to our hospital between 1992 and 2017 were included. Results 14 female patients were included. The time from anorexia nervosa onset to the initial visit with a nephrologist was 17.8 years. At the first visit, median body mass index was 13.4kg/m2, median serum creatinine level was 1.9mg/dL, and median serum potassium level was 2.7mmol/L. All patients showed hypokalemia and addictive vomiting or diuretic/laxative abuse. During the median observation period of 3.1 years, kidney outcomes occurred in 9 patients, and 2 died due to their anorexia nervosa. 4 patients underwent kidney biopsy. The kidney biopsy findings of these patients included hypertrophy of the juxtaglomerular apparatus, advanced glomerular collapse, and interstitial fibrosis, consistent with ischemic kidney injury and hypokalemic nephropathy. Limitations The sample size was small, and kidney function was assessed based on serum creatinine levels in patients with anorexia nervosa with low muscle mass. Conclusions Most patients with anorexia nervosa referred to nephrologists had kidney disease at the time of the first visit. Improving kidney outcomes of patients with anorexia nervosa may require earlier collaboration between psychiatrists and nephrologists.

Background The incidence of acute tubulointerstitial nephritis (ATIN) related to drugs has dramatically increased over recent years. A new subtype of ATIN, apparently different from classical drug-related ATIN, has emerged that has been related to the administration of immune checkpoint inhibitors (ICIs). We investigated these differences between ICI-related ATIN (ICI ATIN) and non-ICI-related ATIN in terms of clinical features, response to treatment with steroids and the evolution of kidney function. Methods A total of 47 patients diagnosed with ATIN from two centres were recruited. Of these, 13 patients presented with ATIN during ICI treatment and 34 were diagnosed with ATIN attributed to other drugs. The main demographic, clinical and analytical variables such as gender, age and current medication were recorded. The type of malignancy, oncological treatment, ICI dose and presence of extrarenal immune-related adverse events were also reviewed. Renal biopsy diagnosis, time to drug withdrawal and ATIN-specific treatment, as well as laboratory data during follow-up, were also studied. Results Patients diagnosed with ICI ATIN presented with lower creatinine (ICI ATIN 3.8 ± 1.03 versus classical ATIN 5.98 ± 4.15 mg/dL, P = 0.007) at diagnosis and higher urinary leucocyte counts (ICI ATIN 263.2 ± 418.04 versus classical ATIN 133.55 ± 284.62, P = 0.048) compared with patients with non-ICI-related ATIN. Time from initiation of the culprit drug to ATIN diagnosis was longer in patients with ICI ATIN than in those with classical ATIN (197.07 ± 184.99 versus 114.4 ± 352.16 days, P = 0.006). In addition, during follow-up, the slope of decreasing creatinine over time was lower for ICI ATIN compared with non-ICI-related ATIN. Conclusions In this study, we analysed differences between ICI ATIN and classical ATIN. We found that patients with ICI ATIN presented with a larger latency period after culprit drug initiation, milder acute kidney injury and slower creatinine amelioration compared with those with classical ATIN. These results may, in part, be ascribed to potential differences in the pathological mechanisms involved in ATIN development, suggesting that ICI and classical ATIN may be different diseases with similar renal histologies.

Introduction To prevent bleeding after native kidney biopsy (NKB), nephrologists often prescribe desmopressin, especially for patients with reduced estimated glomerular filtration rate (eGFR) at risk of uremia-related platelet dysfunction. However, only 1 randomized study has suggested a beneficial effect for desmopressin in patients with eGFR ≥60 ml/min per 1.73 m2. This retrospective cohort study aimed to evaluate desmopressin effect on postbiopsy bleeding in all patients, regardless of eGFR and other comorbidities. Methods In this retrospective cohort study, all adult patients who underwent an NKB from April 1, 2013, to April 30, 2018, in a tertiary hospital were identified. The association between desmopressin use and bleeding complications, including hemoglobin fall, transfusion, hematoma, symptomatic hematoma, urgent radiologic study, and hypotension, was analyzed using multivariable logistic regression models. Results A total of 413 native kidney biopsies were studied, 79% of which were performed after receiving desmopressin. Patients receiving desmopressin had worse chronic kidney disease (eGFR 28 vs. 45 ml/min per 1.73 m2; P < 0.001) and were more often hospitalized (48% vs. 32%; P = 0.009). Despite higher bleeding risk, patients using desmopressin had a similar likelihood of symptomatic hematomas (odds ratio [OR], 0.39; 95% confidence interval [CI], 0.13–1.14) and a lower need for urgent radiologic studies (OR, 0.33; 95% CI, 0.11–0.98). Conclusion Patients at higher risk of bleeding using desmopressin before kidney biopsy had bleeding complications similar to those not using desmopressin. These results highlight potential important clinical and financial benefits of desmopressin use before kidney biopsy., Graphical abstract

Oliguric acute kidney injury (AKI) with minimal change nephrotic syndrome (MCNS) has long been recognized. Several mechanisms such as hypovolemia due to hypoalbuminemia and the nephrosarca hypothesis have been proposed. However, the precise mechanism by which MCNS causes AKI has not been fully elucidated. Herein, we describe an elderly patient with AKI caused by MCNS who fully recovered after aggressive volume withdrawal by hemodialysis and administration of a glucocorticoid. A 75-year-old woman presented with diarrhea and oliguria, and laboratory examination revealed nephrotic syndrome (NS) and severe azotemia. Fluid administration had no effect on renal dysfunction, and hemodialysis was initiated. Her renal function improved upon aggressive fluid removal through hemodialysis. Renal pathological findings revealed minimal change disease with faint mesangial deposits of IgA. After administration of methylprednisolone pulse therapy followed by oral prednisolone, she achieved complete remission from NS. The clinical course of this case supports the nephrosarca hypothesis regarding the mechanism of AKI caused by MCNS. Furthermore, appropriate fluid management and kidney biopsy are also important in elderly patients with AKI caused by NS.

Monoclonal gammopathy of renal significance (MGRS) is a new nosology in modern nephrology and oncohematology. MGRS is defined as kidney injury due to nephrotoxic monoclonal immunoglobulin produced by the B-cell line clone which does not reach the hematological criteria for specific treatment initiation. Monoclonal proteins pathological effects on kidney parenchyma result in irreversible decline of kidney function till the end stage renal disease that in line with the position of International Consensus of hematologists and nephrologists determinates critical necessity for clone specific treatment in patients with MGRS despite the absence of hematological indications for treatment initiation. Main challenge of MGRS in Russian Federation is an inaccessibility of an in-time diagnostic and appropriate treatment for the great majority of patients due to the following reasons: 1) limited knowledge about the MGRS among hematologists and nephrologists; 2) lack of necessary diagnostic resources in most health-care facilities; 3) lack of approved clinical recommendations and medical economic standards for treatment of this pathological entity. Consensus document comprises the opinion of experts leading nephrologists and hematologists of Russian Federation on the problem of MGRS including the incoherence in nosology classification, diagnostics approach and rationale for clone specific treatment. Consensus document is based on conclusions and agreements reached during the conference of leading nephrologists and hematologists of Russia which was held in the framework of symposia Plasma cell dyscrasias and lymphoproliferative diseases: modern approaches to therapy, 1516 of March 2019, Pavlov First Saint Petersburg State Medical University. The present Consensus is intended to define the principal practical steps to resolve the problem of MGRS in Russian Federation that are summarized as final clauses.Моноклональная гаммапатия ренального значения (МГРЗ) представляет собой новую нозологическую группу в современной нефрологии и онкогематологии. Под МГРЗ понимают поражение почек, обусловленное действием нефротоксичного моноклонального иммуноглобулина, продуцируемого клоном В-клеточной линии, который не достигает критериев, необходимых для начала противоопухолевой терапии по онкогематологическим показаниям. Результатом воздействия моноклонального белка на почечную паренхиму является неуклонное прогрессирование дисфункции почек вплоть до утраты функции органа, что в соответствии с единой позицией международного консенсуса гематологов и нефрологов определенно указывает на необходимость клон-ориентированного лечения МГРЗ, несмотря на отсутствие критериальных онкогематологических показаний. Основной проблемой МГРЗ в Российской Федерации является недоступность для большинства пациентов своевременной диагностики и лечения данной патологии, что обусловлено, во-первых, недостаточной осведомленностью гематологов и нефрологов страны в отношении МГРЗ, во-вторых, отсутствием в большинстве медицинских учреждений необходимых диагностических ресурсов, в-третьих, отсутствием утвержденных рекомендаций и медико-экономических стандартов лечения этой болезни. Текст настоящего консенсуса заключает в себе мнение специалистов РФ в отношении нозологической классификации, диагностики и подходов к терапии МГРЗ и основан на итогах проведенного совместного совещания ведущих гематологов и нефрологов страны. Совещание состоялось 1516 марта 2019 г. в рамках симпозиума Плазмоклеточные дискразии и лимфопролиферативные заболевания: новые подходы к терапии, проведенного в ФГБОУ ВО Первый СПбГМУ им. акад. И.П. Павлова. Настоящий консенсус гематологов и нефрологов призван наметить основные практические пути решения проблемы МГРЗ в РФ, которые кратко сформулированы в виде заключительных положений.

Apolipoprotein L1 (APOL1) risk variants G1 and G2 are known to result in risk for kidney disease in patients of African ancestry. APOL1-associated nephropathy typically occurs in association with certain environmental factors or systemic diseases. As such, there has been increasing evidence of the role of interferon (IFN) pathways in the pathogenesis of APOL1-associated collapsing glomerulopathy in patients with human immunodeficiency virus (HIV) infection and systemic lupus erythematosus, 2 conditions that are associated with high IFN levels. Collapsing glomerulopathy has also been described in patients receiving exogenous IFN therapy administered for various medical conditions. We describe a patient with a genetic condition that results in an increased IFN state, stimulator of IFN genes (STING)-associated vasculopathy with onset in infancy (SAVI), who developed collapsing glomerulopathy during a flare of his disease. The patient was found to have APOL1 G1 and G2 risk variants. This case supports the role of IFN in inducing APOL1-associated collapsing glomerulopathy.

Background To date, there is insufficient knowledge about crescentic glomerulonephritis (cGN), the most frequent immunologic cause of acute kidney injury in children. Methods Over a period of 16 years, we retrospectively analyzed kidney biopsy results, the clinical course, and laboratory data in 60 pediatric patients diagnosed with cGN. Results The underlying diseases were immune complex GN (n = 45/60, 75%), including IgA nephropathy (n = 19/45, 42%), lupus nephritis (n = 10/45, 22%), Henoch-Schoenlein purpura nephritis (n = 7/45, 16%) and post-infectious GN (n = 7/45, 16%), ANCA-associated pauci-immune GN (n = 10/60, 17%), and anti-glomerular basement-membrane GN (n = 1/60, 2%). Patient CKD stages at time of diagnosis and at a median of 362 days (range 237–425) were CKD I: n = 13/n = 29, CKD II: n = 15/n = 9, CKD III: n = 16/n = 7, CKD IV: n = 3/n = 3, CKD V: n = 13/n = 5. Course of cGN was different according to class of cGN, duration of disease from first clinical signs to diagnosis of cGN by biopsy, percentage of crescentic glomeruli, amount of tubular atrophy/interstitial fibrosis and necrosis on renal biopsy, gender, age, nephrotic syndrome, arterial hypertension, dialysis at presentation, and relapse. Forty-eight/60 children were treated with ≥ 5 (methyl-) prednisolone pulses and 53 patients received oral prednis(ol)one in combination with mycophenolate mofetil (n = 20), cyclosporine A (n = 20), and/or cyclophosphamide (n = 6), rituximab (n = 5), azathioprine (n = 2), tacrolimus (n = 1), and plasmapheresis/immunoadsorption (n = 5). Conclusions The treatment success of cGN is dependent on early diagnosis and aggressive therapy, as well as on the percentage of crescentic glomeruli on renal biopsy and on the underlying type of cGN. CsA and MMF seem to be effective alternatives to cyclophosphamide.

Introduction: Kidney biopsy is performed to assess if an extended criteria graft can be used for transplantation. It may be performed before or after cross-clamping during organ procurement. This study aims to evaluate whether the timing of biopsy may modify cold ischemia times (CIT) and/or graft outcomes. Methods: Kidney transplants performed in our center from January 2007 to December 2017 were analyzed. Grafts with preimplantation kidney biopsy were included. Biopsies were performed during surgical back table (ex situ kidney biopsy [ESKB]) until 2012 and since then before the aortic cross-clamping (in situ kidney biopsy [ISKB]). To overcome biases owing to different distributions, a propensity score model was developed. The study population consists in 322 patients, 115 ESKB, and 207 ISKB. Results: CIT was significantly lower for ISKB (730 min ISKB vs. 840 min ESKB, p value = 0.001). In both crude (OR 0.27; 95% confidence interval, 95% CI 0.12–0.60; p value = 0.002) and adjusted analyses (OR 0.37; 95% CI 0.14–0.94; p value = 0.039), ISKB was associated with a reduced odd of graft loss when compared to ESKB. Discussion/Conclusion: Performing preimplantation kidney biopsy during the recovery, prior to the aortic cross-clamping, may be a strategy to reduce CIT and improve transplant outcomes.

Background: Galectin-3 (Gal-3) is a multifunctional glycan-binding protein shown to be linked to chronic inflammation and fibrogenesis. Plasma Gal-3 is associated with proteinuria and renal dysfunction, but its role has never been confirmed with kidney biopsy results. In our study, we aimed to explore the expression of Gal-3 in biopsy-proven patients, and we tested the hypothesis that chronic kidney disease (CKD) leads to upregulation of plasma Gal-3 expression in corresponding biopsy findings and RNA sequencing analysis.Method: In 249 patients (male/female: 155/94, age: 57.2 ± 16.3 years) who underwent kidney biopsy, plasma levels of Gal-3 were measured to estimate the association of renal fibrosis. Relationships between plasma Gal-3 levels, estimated glomerular filtration rate (eGFR) and renal histology findings were also assessed. We further examined the gene expression of Gal-3 in RNA-sequencing analysis in biopsy-proven patients.Results: Compared to patients without CKD, CKD patients had higher levels of plasma Gal-3 (1,016.3 ± 628.1 pg/mL vs. 811.6 ± 369.6 pg/ml; P = 0.010). Plasma Gal-3 was inversely correlated with eGFR (P = 0.005) but not with proteinuria. Higher Gal-3 levels were associated with interstitial fibrosis, tubular atrophy and vascular intimal fibrosis. RNA-sequencing analysis showed the upregulation of Gal-3 in fibrotic kidney biopsy samples, and the differentially expressed genes were mainly enhanced in immune cell activation and the regulation of cell-cell adhesion.Conclusions: Plasma Gal-3 levels are inverse correlated with eGFR but positively correlated with renal fibrosis, which may be involved in the immune response and associated pathways. These findings support the role of Gal-3 as a predictive marker of renal fibrosis.

We determined the association between CD14++CD16+ monocytes and subclinical infiltrates that do not reach the histological threshold for rejection (≥Banff IA). We studied low-immunological-risk kidney-transplant recipients in a clinical trial (NCT02284464, EudraCT 2012-003298-24) whose protocol biopsy in the third month showed no significant changes or borderline lesions (BL). Flow cytometry was used to analyze the percentage of CD14++CD16+ monocytes in peripheral blood (PB) and blood from a fine-needle-aspiration biopsy (FNAB). A protocol biopsy was performed in 81 low-immunological-risk patients, of whom 15 were excluded (BK polyomavirus and rejection). The 28 (42.4%) with borderline lesions had significantly low levels of CD14++CD16+ in PB compared to patients with normal biopsies (7.9 ± 5.4 vs. 13.0 ± 12.8, p = 0.047). Patients without significant changes had similar percentages of CD14++CD16+ monocytes in the graft blood (GB) and FNAB blood. The percentage of these monocytes in the patients with an interstitial infiltrate, however, increased significantly in the FNAB blood compared to the GB: 16.9 ± 16.6 vs. 7.9 ± 5.4, p = 0.006. A difference of 50% in CD14++CD16+ in the GB versus the PB was a significant risk factor (p = 0.002) for BL, increasing the risk seven times. A decrease in CD14++CD16+ in the PB could be associated with the recruitment of these cells to the graft tissue in cases of subclinical BL inflammatory infiltrates below the threshold for rejection.

Patients with IgA vasculitis (IgAV), an immune complex-mediated disease, may exhibit kidney involvement—IgAV with nephritis (IgAVN). The kidney-biopsy histopathologic features of IgAVN are similar to those of IgA nephropathy, but little is known about histopathologic disease severity based on the interval between purpura onset and diagnostic kidney biopsy. We assessed kidney histopathology and clinical and laboratory data in a cohort of adult patients with IgAVN (n = 110). The cases were grouped based on the interval between the onset of purpura and kidney biopsy: Group 1 (G1, &lt, 1 month, n = 14), Group 2 (G2, 1–6 months, n = 58), and Group 3 (G3, &gt, 6 months, n = 38). Glomerular leukocytes were more common in G1 than in the other groups (p = 0.0008). The proportion of neutrophils among peripheral-blood leukocytes was the highest in the patients biopsied within a month after onset of purpura (G1: 71 ± 8%). In the patients with an interval &gt, 6 months, the neutrophil proportion was lower, 60%. Moreover, the glomerular mesangial proliferation score correlated with the serum total IgA concentration (p = 0.0056). In conclusion, IgAVN patients biopsied &lt, 1 month from purpura onset showed an elevated percentage of blood neutrophils and glomerular leukocytes, consistent with an acute-onset inflammatory reaction. In all IgAVN patients, the mesangial proliferation score correlated with the serum IgA level.

Quantification of the M-type phospholipase A2 receptor antibodies (anti-PLA2R) is now an essential tool for diagnosis and management of primary membranous nephropathy (MN). Since October 2018, Hôpital Maisonneuve-Rosemont (HMR) has been designated as Quebec's reference center for serum anti-PLA2R antibody testing by theTo describe the 2-step method of serum qualitative and quantitative anti-PLA2R antibody testing during its first year of use in Quebec and analyze its diagnostic value in the province's population.Retrospective cohort study.Single-center academic teaching hospital in Quebec, Canada.All patients who had a serum anti-PLA2R antibody test analyzed at HMR from October 1, 2018, to October 1, 2019, were included in the study.Serum anti-PLA2R antibodies were screened by indirect immunofluorescence tests. If results were positive or undetermined, it was followed by a quantitative enzyme-linked immunosorbent assay (ELISA) test. Both tests were based on a commercial kit developed by the same company.We calculated sensitivity, specificity, predictive value, and likelihood ratio for both tests, using kidney biopsy findings performed at HMR as the gold standard.In Quebec, a total of 1690 tests were performed among 1025 patients during the study year. A small proportion of these patients (8%) were followed at HMR. Patients tested at HMR and in the rest of Quebec had similar characteristics. Test validity was only characterized for patients tested at HMR. Sensitivity and specificity were, respectively, 58% and 100% for the qualitative test, and 71% and 100% for the quantitative test. The combined net sensitivity was 42% and the net specificity 100%. The net positive and negative predictive value were 100% and 84% respectively, whereas the net negative likelihood ratio was 0.58.As the detailed analysis was only possible in the small proportion of patients clinically followed at HMR, there is a possible selection bias. Another potential selection bias was the focus on patients who were selected to have a kidney biopsy, probably because of more severe disease, higher probability of glomerulonephritis, or lesser number of comorbidities. Given the retrospective nature of this study, there was no systematic kidney biopsy or serum PLA2R antibody testing performed. Finally, we were unable to provide detailed information on the timing between immunosuppressive therapy and anti-PLA2R results.Serum anti-PLA2R antibody testing was widely used in Quebec during its first year of availability. A 2-step approach, using a qualitative test first, followed by a quantitative test if the results are positive or undetermined, appears efficient to avoid useless quantitative testing in negative patients and to better characterize undetermined results on immunofluorescence.Due to the retrospective nature of this study, no trial registration was performed.La quantification des anticorps des récepteurs de la phospholipase A2 de type M (anti-PLA2R) est désormais un outil essentiel pour le diagnostic et la prise en charge de la glomérulonéphrite extra-membraneuse primaire (GEMp). Depuis octobre 2018, l’Hôpital Maisonneuve-Rosemont (HMR) a été désigné par l’Institut National d’Excellence en Santé et Services Sociaux (INESSS)—l’organisme règlementant l’usage des médicaments et des tests au Québec—comme le centre hospitalier de référence dans la province pour le dépistage des anticorps sériques anti-PLA2R.Décrire la méthode en deux étapes du test qualitatif et quantitatif des anticorps anti-PLA2R sériques au cours de sa première année d’utilisation au Québec et évaluer sa valeur diagnostique dans la population de la province.Étude de cohorte rétrospective.Un centre hospitalier universitaire du Québec (Canada).Ont été inclus tous les patients dont le test des anticorps sériques anti-PLA2R a été analysé à HMR entre le 1er octobre 2018 et le 1er octobre 2019.Les anticorps sériques anti-PLA2R ont été détectés par immunofluorescence indirecte. Les résultats positifs ou indéterminés ont été suivis d’un test ELISA quantitatif. Les deux tests ont été réalisés à l’aide de trousses commerciales développées par la même entreprise.Nous avons analysé la sensibilité, la spécificité, la valeur prédictive et le rapport de vraisemblance des deux tests avec comme référence des résultats de biopsie rénale obtenus à HMR.Au Québec, au cours de l’année de l’étude, 1 690 tests ont été effectués sur 1 025 patients; une faible proportion de ces patients (8 %) étaient suivis à HMR. Les patients, qu’ils aient été testés à HMR et ailleurs au Québec, présentaient des caractéristiques semblables. La validité du test n’a été caractérisée que pour les patients testés à HMR. La sensibilité et la spécificité s’établissaient respectivement à 58 % et à 100 % pour le test qualitatif, et à 71 % et 100 % pour le test quantitatif. La sensibilité nette combinée était de 42 % et la spécificité nette, de 100 %. Les valeurs prédictives nettes, positive et négative, étaient respectivement de 100 % et de 84 %, alors que le ratio net de probabilité négative était de 0,58.L’étude présente un possible biais de sélection puisque l’analyse détaillée n’était possible que pour la faible proportion de patients suivis à HMR. L’accent mis sur les patients sélectionnés pour une biopsie rénale, probablement en raison d’une maladie plus grave, d’une probabilité plus élevée de glomérulonéphrite ou d’un moins grand nombre de comorbidités, constitue un autre possible biais de sélection. Aucune biopsie rénale ou test d’anticorps de PLA2R sérique systématique n’a été effectué puisque l’étude est rétrospective. Enfin, il n’a pas été possible de fournir des informations détaillées sur le temps écoulé entre le traitement immunosuppresseur et les résultats du test d’anticorps anti-PLA2R.Le test d’anticorps sériques anti-PLA2R a été largement utilisé au Québec au cours de sa première année de disponibilité. Une approche en deux étapes, constituée d’un test qualitatif suivi d’un test quantitatif si le résultat est positif ou indéterminé, semble efficace pour éviter de procéder inutilement à des tests quantitatifs chez les patients négatifs et pour caractériser plus précisément les résultats indéterminés par immunofluorescence.L’essai n’a pas été enregistré puisqu’il s’agit d’une étude rétrospective.

Purpose: To assess the utility of non-contrast enhanced native T1 mapping of the renal cortex in assessing renal fibrosis for patients with chronic glomerulonephritis (CGN).Methods: A total of 119 patients with CGN and 19 healthy volunteers (HVs) were recruited for this study. Among these patients, 43 had undergone kidney biopsy measurements. Clinical information and biopsy pathological scores were collected. According to the results of the renal biopsy, the patients were classified into the high (25–50%), low (Results: Compared with those of the HVs, the T1 values were significantly higher in patients at all stages of chronic kidney disease (CKD) (all p < 0.05). Significant T1 differences were also revealed between patients with different stages of CKD (p < 0.05). Additionally, the T1 value correlated well with CKD stage (p < 0.05), except between CKD 2 and 3. In addition, the T1 value was positively correlated with cystatin C, neutrophil gelatinase-associated lipocalin, and serum creatinine and negatively correlated with hemoglobin, kidney length, estimated glomerular filtration rate and hematocrit (all p < 0.05). Compared with those of the no IF group, the T1 values were increased in the low- and high-IF groups (both p < 0.05). Logistic regression analysis showed that an elevated T1 value was an independent risk factor for renal fibrosis. ROC analysis suggested that the optimal critical value of T1 for predicting renal fibrosis was 1,695 ms, with a specificity of 0.778 and a sensitivity of 0.625.Conclusion: Native T1 mapping demonstrated good diagnostic performance in evaluating renal function and was an effective noninvasive method for detecting renal fibrosis in CGN patients.

Churg–Strauss syndrome (CSS) is a granulomatous small-vessel vasculitis. Asthma is seen in the majority of patients with CSS, but atypical nonasthmatic forms of CSS are also being recognized. We herein describe a 67-year-old woman with a history of chronic pyelonephritis and drug allergy reactions who was admitted to our hospital because of worsening renal function preceded by fever, purpura, sinusitis, and a positive urine culture that confirmed a urinary infection. She was initially treated with pipemidic acid for 7 days, followed by clarithromycin for sinusitis. Laboratory tests on admission showed an absolute eosinophil count of 1750 cells/µL and serum creatinine concentration of 4.72 mg/dL. Urine and blood cultures showed no growth. Kidney biopsy revealed crescent formations with diffuse interstitial fibrosis and foci of eosinophil infiltration. An atypical form of CSS was diagnosed based on tissue eosinophilia, peripheral eosinophilia, and sinusitis. Intravenous methylprednisolone and cyclophosphamide pulse therapy together with hemodialysis treatment improved the patient’s clinical condition but did not resolve the kidney damage. The onset of an atypical form of CSS in our patient manifested as symptoms and signs mimicking those of chronic pyelonephritis and drug allergy reactions. The patient’s chronic kidney disease finally progressed to dialysis dependence.

Immunoglobulin M nephropathy (IgMN) is an idiopathic glomerulonephritis characterized by diffuse deposits of IgM in the glomerular mesangium. However, its renal prognosis remains unknown. We compared renal outcomes of IgMN patients with those of patients with minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), or mesangial proliferative glomerulonephritis (MsPGN) from a prospective observational cohort, with 1791 patients undergoing native kidney biopsy in eight hospitals affiliated with The Catholic University of Korea between December 2014 and October 2020. IgMN had more mesangial proliferation and matrix expansion than MsPGN and more tubular atrophy and interstitial fibrosis than MCD. IgMN patients had decreased eGFR than MCD patients in the earlier follow-up. However, there was no significant difference in urine protein or eGFR among all patients at the last follow-up. When IgMN was divided into three subtypes, patients with FSGS-like IgMN tended to have lower eGFR than those with MCD-like or MsPGN-like IgMN but higher proteinuria than MsPGN-like IgMN without showing a significant difference. The presence of hypertension at the time of kidney biopsy predicted ≥20% decline of eGFR over two years in IgMN patients. Our data indicate that IgMN would have a clinical course and renal prognosis similar to MCD, FSGS, and MsPGN.

ANCA-associated vasculitis (AAV) poses a significant risk of kidney failure, kidney biopsy remains a key prognostic tool. The histopathologic classification of AAV glomerulonephritis (GN) developed by Berden et al. showed correlation between GN classes and kidney outcomes, ANCA Renal Risk Score (ARRS) included tubular atrophy and interstitial fibrosis (TA/IF) as an additional parameter for risk assessment. We aimed to evaluate kidney survival across AAV GN classes and ARRS groups. A single-center retrospective study included 85 adult patients with biopsy-proven AAV kidney disease followed in the period of 2000–2020. Primary outcome was kidney survival at the end of 18 (5, 66) months follow-up, and kidney death was considered as stage 5 CKD. We found significant differences in kidney survival for sclerotic, mixed, crescentic and focal AAV GN classes: 19%, 76.2%, 91.7% and 100%, respectively (p = 0.009). Kidney survival was 0%, 75.6% and 100% for the high-, medium- and low-risk ARRS groups, respectively (p &lt, 0.001), TA/IF analysis showed kidney survival at 49.6% vs. 87.7% for widespread and mild TA/IF, respectively (p = 0.003). Kidney survival was significantly lower in anti-MPO-ANCA versus anti-PR3-ANCA carriers (50.3% and 78.1%, respectively, p = 0.045). We conclude that unfavorable AAV kidney outcomes are associated with sclerotic GN class by Berden’s classification, ARRS high risk group, and anti-MPO-ANCA subtype.

Kidney failure is common in patients with Coronavirus Disease-19 (COVID-19) resulting in increased morbidity and mortality. In an international collaboration, 284 kidney biopsies were evaluated to improve understanding of kidney disease in COVID-19. Diagnoses were compared to five years of 63,575 native biopsies prior to the pandemic and 13,955 allograft biopsies to identify diseases increased in patients with COVID-19. Genotyping for APOL1 G1 and G2 alleles was performed in 107 African American and Hispanic patients. Immunohistochemistry for SARS-CoV-2 was utilized to assess direct viral infection in 273 cases along with clinical information at the time of biopsy. The leading indication for native biopsy was acute kidney injury (45.4%), followed by proteinuria with or without concurrent acute kidney injury (42.6%). There were more African American patients (44.6%) than patients of other ethnicities. The most common diagnosis in native biopsies was collapsing glomerulopathy (25.8%) which associated with high-risk APOL1 genotypes in 91.7% of cases. Compared to the five-year biopsy database, the frequency of myoglobin cast nephropathy and proliferative glomerulonephritis with monoclonal IgG deposits was also increased in patients with COVID-19 (3.3% and 1.7%, respectively), while there was a reduced frequency of chronic conditions (including diabetes mellitus, IgA nephropathy, and arterionephrosclerosis) as the primary diagnosis. In transplants, the leading indication was acute kidney injury (86.4%), for which rejection was the predominant diagnosis (61.4%). Direct SARS-CoV-2 viral infection was not identified. Thus, our multi-center large case series identified kidney diseases that disproportionately affect patients with COVID-19, demonstrated a high frequency of APOL1 high-risk genotypes within this group, with no evidence of direct viral infection within the kidney., Graphical abstract

The relationship between focal segmental glomerulosclerosis (FSGS) and pregnancy is complex and not completely elucidated. Pregnancy in patients with FSGS poses a high risk for complications, possibly due to hemodynamic factors, imbalance between angiogenic and antiangiogenic factors, and hormonal conditioning. Although poor clinical outcomes associated with collapsing FSGS are common outside of pregnancy, the prognosis during pregnancy is not well documented. We report 3 patients who developed collapsing FSGS during pregnancy, 2 of whom had presumed underlying FSGS. Two patients underwent biopsy during pregnancy, and 1, during the puerperium. None of the 3 patients improved spontaneously after delivery, and 1 experienced a rapid deterioration in kidney function and proteinuria after delivery. Aggressive immunosuppressive therapy led to a full response in 1 case (without chronic lesions) and to partial responses in the remaining 2 cases. These cases suggest that collapsing lesions should be considered in patients with FSGS who develop a rapid increase in serum creatinine level or proteinuria during pregnancy and that these lesions may at least partially respond to treatment.

BackgroundDespite improvement in short-term outcome of kidney transplants, the long-term survival of kidney transplants has not changed over past decades. Kidney biopsy is the gold standard of transplant pathology but it’s invasive. Quantification of transplant blood flow could provide a novel non-invasive method to evaluate transplant pathology. The aim of this retrospective cross-sectional pilot study was to evaluate positron emission tomography (PET) as a method to measure kidney transplant perfusion and find out if there is correlation between transplant perfusion and histopathology.MethodsRenal cortical perfusion of 19 kidney transplantation patients [average time from transplantation 33 (17–54) months; eGFR 55 (47–69) ml/min] and 10 healthy controls were studied by [15O]H2O PET. Perfusion and Doppler resistance index (RI) of transplants were compared with histology of one-year protocol transplant biopsy.ResultsRenal cortical perfusion of healthy control subjects and transplant patients were 2.7 (2.4–4.0) ml min− 1 g− 1and 2.2 (2.0–3.0) ml min− 1 g− 1, respectively (p = 0.1). Renal vascular resistance (RVR) of the patients was 47.0 (36.7–51.4) mmHg mL− 1min− 1g− 1and that of the healthy 32.4 (24.6–39.6) mmHg mL− 1min−1g−1(p = 0.01). There was a statistically significant correlation between Doppler RI and perfusion of transplants (r = − 0.51,p = 0.026). Transplant Doppler RI of the group of mild fibrotic changes [0.73 (0.70–0.76)] and the group of no fibrotic changes [0.66 (0.61–0.72)] differed statistically significantly (p = 0.03). No statistically significant correlation was found between cortical perfusion and fibrosis of transplants (p = 0.56).Conclusions[15O]H2O PET showed its capability as a method in measuring perfusion of kidney transplants. RVR of transplant patients with stage 2–3 chronic kidney disease was higher than that of the healthy, although kidney perfusion values didn’t differ between the groups. Doppler based RI correlated with perfusion and fibrosis of transplants.

BACKGROUND The histopathological findings on the failing kidney allograft in the modern era is not well studied. In this study, we present our experience working with kidney transplant recipients with graft failure within one year of the biopsy. AIM To report the histopathological characteristics of failed kidney allografts in the current era of immunosuppression based on the time after transplant, cause of the end-stage renal disease and induction immunosuppressive medications. METHODS In a single-center observational study, we characterized the histopathological findings of allograft biopsies in kidney transplant recipients with graft failure within one year after the biopsy. RESULTS We identified 329 patients with graft failure that met the selection criteria between January 1, 2006 and December 31, 2016. The three most common biopsy findings were interstitial fibrosis and tubular atrophy (IFTA, 53%), acute rejection (AR, 43%) and transplant glomerulopathy (TG, 33%). Similarly, the three most common causes of graft failure based on the primary diagnosis were AR (40%), TG (17%), and IFTA (13%). Most grafts failed within two years of post-transplant (36%). Subsequently, approximately 10%-15% of grafts failed every two years: > 2-4 years (16%), > 4-6 years (13%), > 6-8 years (11%), > 8-10 years (9%) and > 10 years (16%). AR was the most common cause of graft failure in the first six years (48%), whereas TG was the most prevalent cause of graft failure after 6 years (32%) of transplant. CONCLUSION In the current era of immunosuppression, AR is still the most common cause of early graft failure, while TG is the most prevalent cause of late graft failure.

BACKGROUND AND OBJECTIVES: In kidney transplant recipients, elevated circulating advanced glycation endproducts (AGEs) are the result of increased formation and decreased kidney clearance. AGEs trigger several intracellular mechanisms that ultimately yield excess cardiovascular disease. We hypothesized that, in stable kidney transplant recipients, circulating AGEs are associated with long-term risk of cardiovascular mortality, and that such a relationship is mediated by inflammatory, oxidative stress, and endothelial dysfunction biomarkers. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Prospective cohort study of stable kidney transplant recipients recruited between 2001 and 2003 in a university setting. We performed multivariable-adjusted Cox regression analyses to assess the association of AGEs (i.e., N(ε)-[Carboxymethyl]lysine (CML) and N(ε)-[Carboxyethyl]lysine (CEL), measured by tandem mass spectrometry) with cardiovascular mortality. Mediation analyses were performed according to Preacher and Hayes’s procedure. RESULTS: We included 555 kidney transplant recipients (age 51±12 years, 56% men). During a median follow-up of 6.9 years, 122 kidney transplant recipients died (52% deaths were due to cardiovascular causes). CML and CEL concentrations were directly associated with cardiovascular mortality (respectively, hazard ratio, 1.55; 95% confidence interval, 1.24 to 1.95; P

Light chain proximal tubulopathy is a rare M-proteinemia–related nephropathy. The inclusions, composed of light chains in light chain proximal tubulopathy, are generally crystalline, and most exhibit a rhombic shape. Noncrystalline structures, such as rods or needle shapes, may also be present. In our patient, one of the noncrystalline structures, fibrillary inclusions in the cytoplasm, were observed, as previously reported in only 4 patients whose primary disease was either multiple myeloma or monoclonal gammopathy of renal significance. This is the first report involving lymphoma. Early diagnosis of light chain proximal tubulopathy is important because those who undergo chemotherapy have an improved kidney prognosis. However, in cases of kidney involvement with blood disorders, thrombocytopenia is often present. Therefore, in our case, open kidney biopsy was selected. Noncrystalline light chain proximal tubulopathy is believed to be less likely to cause Fanconi syndrome. However, Fanconi syndrome was observed in 3 of the 4 patients with fibrillary inclusions. In our case, hypouricemia was improved by chemotherapy, suggesting that the patient presented with Fanconi syndrome. Noncrystalline light chain proximal tubulopathy with fibrillary inclusions may cause Fanconi syndrome, similar to crystalline light chain proximal tubulopathy. We report a case of light chain proximal tubulopathy with fibrillary inclusions complicated by low-grade B-cell lymphoma in which early treatment was successful. Index Words: Light chain proximal tubulopathy, fibrillary inclusion, lymphoma, Fanconi syndrome, hypouricemia, kidney biopsy, monoclonal gammopathy of renal significance (MGRS)

Introduction: Lupus nephritis (LN) is one of the most severe manifestations of systemic lupus erythematosus (SLE), resulting in increased morbidity and mortality. The gold standard for diagnosis of LN is a renal biopsy. Considering the importance of the biopsy in determining long-term prognostication and treatment decisions, it is crucial to assess renal histopathology with utmost accuracy and precision. This review represents a systematic search of published literature to estimate the degree of interpathologist reproducibility in current assessment of LN. Methods: Using the PubMed and Google Scholar search engines, studies analyzing the agreement of 4 or more pathologists assessing LN slides using the ISN/Renal Pathology Society (RPS) classification, activity index, and chronicity index were selected for analysis in this systematic review. Results: In reviewing 6 qualifying studies (those analyzing the agreement of 4 or more pathologists using the ISN/RPS classification, activity index, and chronicity index) for the assignment of ISN/RPS class was 0.325 (interquartile range [IQR] 0.2405–0.425), which is “poor.” The median interpathologist concordance values for the assigned activity index and chronicity index were “moderate”: 0.52 (IQR 0.51–0.69) and 0.49 (IQR 0.36–0.58), respectively. Conclusion: Thus, the current scoring using the ISN/RPS classification system and activity and chronicity indices for LN exhibits poor interpathologist agreement, which limits its use in clinical practice. Given that this can have severe repercussions on a patient’s treatment and prognosis, efforts to update pathology assessment guidelines, objectively measurable biomarkers, and deep learning approaches are strongly warranted. Keywords: chronic kidney disease, glomerulonephritis, inflammation, kidney biopsy, lupus