The spectrum of biopsy-proven kidney diseases in elderly Chinese patients

Hidden genetics behind glomerular scars: an opportunity to understand the heterogeneity of focal segmental glomerulosclerosis?

Focal segmental glomerulosclerosis (FSGS) is a complex disease which describes different kinds of kidney defects, not exclusively linked with podocyte defects. Since nephrin mutation was first described in association with early-onset nephrotic syndrome (NS), many advancements have been made in understanding genetic patterns associated with FSGS. New genetic causes of FSGS have been discovered, displaying unexpected genotypes, and recognizing possible site of damage. Many recent large-scale sequencing analyses on patients affected by idiopathic chronic kidney disease (CKD), kidney failure (KF) of unknown origin, or classified as FSGS, have revealed collagen alpha IV genes, as one of the most frequent sites of pathogenic mutations. Also, recent interest in complex and systemic lysosomal storage diseases, such as Fabry disease, has highlighted GLA mutations as possible causes of FSGS. Tubulointerstitial disease, recently classified by KDIGO based on genetic subtypes, when associated with UMOD variants, may phenotypically gain FSGS features, as well as ciliopathy genes or others, otherwise leading to completely different phenotypes, but found carrying pathogenic variants with associated FSGS phenotype. Thus, glomerulosclerosis may conceal different heterogeneous conditions. When a kidney biopsy is performed, the principal objective is to provide an accurate diagnosis. The broad spectrum of phenotypic expression and genetic complexity is demonstrating that a combined path of management needs to be applied. Genetic investigation should not be reserved only to selected cases, but rather part of medical management, integrating with clinical and renal pathology records. FSGS heterogeneity should be interpreted as an interesting opportunity to discover new pathways of CKD, requiring prompt genotype-phenotype correlation. In this review, we aim to highlight how FSGS represents a peculiar kidney condition, demanding multidisciplinary management, and in which genetic analysis may solve some otherwise unrevealed idiopathic cases. Unfortunately there is not a uniform correlation between specific mutations and FSGS morphological classes, as the same variants may be identified in familial cases or sporadic FSGS/NS or manifest a variable spectrum of the same disease. These non-specific features make diagnosis challenging. The complexity of FSGS genotypes requires new directions. Old morphological classification does not provide much information about the responsible cause of disease and misdiagnoses may expose patients to immunosuppressive therapy side effects, mistaken genetic counseling, and misguided kidney transplant programs.

Demographic distribution analysis of different glomerular diseases in Southwest China from 2008 to 2022

BACKGROUND

Environmental and lifestyle factors play an etiological role in the pathogenesis of different glomerular diseases. Thus, exploring the epidemic characteristics of renal disease in different nationalities and regions is important.

MATERIALS AND METHODS

Patients who underwent renal biopsy from October 2008 to October 2022 were included. The proportion and change tendency of glomerular diseases and the differences between the sexes and different ages and races were analyzed.

RESULTS

There were 15,146 cases of glomerular diseases (98.5%), involving 7538 males (49.8%) and 7608 females (50.2%). The mean age was 37.0 years (range 0-80 years). The proportion of membranous nephropathy (MN) and diabetic nephropathy (DN) showed an increased trend. The most common primary glomerulonephritis (PGN) was IgA nephropathy (IgAN, 44.6%), followed by minimal-change disease (MCD, 24.3%) and MN (15.4%). Lupus nephritis (LN, 30%) accounted for the largest proportion of SGNs, followed by Henoch-Schonlein purpura nephritis (HSPN, 20.9%) and DN (19.8%). Compared with adults aged 18-60 years old, MCD and HSPN were more common in children and MN and DN in elderly individuals, statistically significant differences. Additionally, the sex and age distribution of PGN and SGN between the Tibetan and Han populations differed significantly, whereby LN was higher in the Han population and HSPN in the Tibetan population.

CONCLUSION

The distribution of glomerular diseases showed age, sex and race differences. This research will be beneficial for providing epidemiological evidence for clinical diagnosis, disease prevention and public health decision-making.

Renal pathology in adult and paediatric population of Japan: review of the Japan renal biopsy registry database from 2007 to 2017

BACKGROUND

The Japan Renal Biopsy Registry (J-RBR), a nationwide, web-based, registry system, started in 2007. This study aimed to summarise the epidemiology of biopsy-diagnosed kidney disease in Japan over 10 years.

METHODS

We analysed the J-RBR database, from 2007 to 2017. Patients' clinical data collected at the time of biopsy and histopathological diagnoses were used for epidemiological and clinicopathologic analyses.

RESULTS

The predominant renal biopsy diagnoses were immunoglobulin A nephropathy (39.2%), lupus nephritis (6.5%) and minimal change disease (6.0%) in younger adults (19-64 years), and membranous nephropathy (17.4%), antineutrophil cytoplasmic antibody-associated vasculitis or anti-glomerular basement membrane glomerulonephritis (13.0%), and immunoglobulin A nephropathy (12.5%) in older adults (≥ 65 years). The percentages of patients diagnosed with membranoproliferative glomerulonephritis and immunoglobulin A nephropathy decreased, whereas those with immunoglobulin A vasculitis and diabetic nephropathy increased over the decade. In paediatric patients (< 19 years), immunoglobulin A nephropathy (36.1%), minimal change disease (17.6%), and immunoglobulin A vasculitis (8.6%) were the predominant diagnoses. The percentage of patients diagnosed with immunoglobulin A vasculitis increased over the decade. Based on the sex distribution, minimal change disease and membranous nephropathy were predominant in men aged < 20 and > 40 years, respectively, whereas immunoglobulin A vasculitis and antineutrophil cytoplasmic antibody-associated vasculitis or anti-glomerular basement membrane glomerulonephritis were predominant in women in their 20s and 30s and aged < 50 years, respectively. Immunoglobulin A nephropathy was predominant in men at most ages and in women in their 20s to 40s.

CONCLUSIONS

This study describes the distribution and changes in kidney biopsy diagnoses over 10 years in Japan and paves the way for future research on kidney diseases in adults and children.

Biopsy-Proven Renal Diseases in the Elderly: A Developing Country Perspective

Renal diseases are one of the common causes of morbidity and mortality in elderly population. Currently, the spectrum of renal diseases in elderly population in our country is unknown. The aim of this study was to determine the pattern of renal diseases in elderly patients in Pakistan. In this retrospective, observational study, we included all consecutive patients aged ≥60 years, on whom native renal biopsies were performed during a period of 25 years from January 1994 to December 2018. The final histologic diagnosis was categorized into four groups, primary glomerular diseases (PGDs), secondary glomerular diseases (SGDs), tubulointerstitial disease (TID), and vascular diseases (VDs). A total of 324 renal biopsies are performed in the study period. The mean age was 64.6 ± 5.1 years, range of 60-80 years with a male-to-female ratio of 3.26:1. The mean serum creatinine at biopsy was 4.1 ± 2.86 mg/dL. Indications for biopsy were acute kidney injury (AKI) in 141 (43.5%), followed by nephrotic syndrome (NS) in 128 (39.5%). Renal disease category was PGD in 204 (63%), SGD in 42 (13%), TID in 58 (17.9%), and VD in 20 (6.1%). Focal segmental glomerulosclerosis (FSGS) is the leading cause of PGD in 55 (27%). Among SGD, amyloidosis was the most common cause in 27 (64.3%). In patients who were biopsied for AKI, majority were crescentic glomerulonephritis accounting for 28 (19.8%). In conclusion, AKI and NS are the common biopsy indications in our population. Overall FSGS is the most common histologic diagnosis in this cohort.

A Spectrum of Biopsy - Proven Renal Disorders and Their Clinicopathological Correlation in Elderly Population From a Tertiary Care Center in South India

Introduction

Chronic kidney disease (CKD) has become a health concern with an extensive burden on incidence and prognosis. While the increasing lifespan contributes to a higher incidence of CKD among the elderly, the diagnostic picture in this age group is complicated by senescence-related changes. A better understanding of the etiology and progression of the disease warrants renal biopsy in such patients. This study aims to explore the histopathological spectrum of native renal biopsies leading to CKD in elderly patients in a tertiary care hospital.

Methods

Among the list of patients who had undergone renal biopsy at our institute from January 2015 to March 2020, elderly patients aged ≥ 60years were chosen for this study. Their demographic details, lab investigations and histopathological reports were collected. The sex distribution and prevalence of different renal diseases was calculated. The subjects were classified into four broad diagnostic groups - primary glomerular disease, diabetic nephropathy, hypertensive nephropathy, and tubulointerstitial disease. The estimated glomerular filtration rate (eGFR) values were calculated and used to stage chronic kidney disease in these patients. Statistical analysis was carried out to find a correlation between diagnostic groups and CKD presence and between serum C3 values and immunofluorescence for the same on biopsy.

Results

One hundred thirty-two patients formed the study sample with a male to female ratio of 1.28:1, showing a slight male predominance. The most common diagnostic group was primary glomerular disease (46%), among which focal segmental glomerulosclerosis (FSGS) was the most common entity (12%). 47.7% and 66.6% of patients in the study sample showed elevated serum blood urea nitrogen (BUN) and creatinine values, respectively. 86% of our study sample had low eGFR values, and the majority (35%) of the patients were classified under CKD stage 3. CKD incidence was high among patients with primary glomerular diseases, but no significant statistical correlation was found. 43.5% of all IF positive cases showed low serum C3 values and established a positive correlation between IF and serum C3 values.

Conclusion

There is no statistically significant correlation of the four diagnostic groups to the CKD. CKD in the elderly may be multifactorial, and a collaborative study across the nations may be needed to further evaluate the etiology.

Acute kidney injury in idiopathic membranous nephropathy with nephrotic syndrome

BACKGROUND AND OBJECTIVES

The impact of acute kidney injury (AKI) on the progression of renal function in idiopathic membranous nephropathy (iMN) with nephrotic syndrome (NS) patients have not yet been reported, we sought to investigate the incidence, clinical features and prognosis of AKI in iMN with NS patients and determine clinical predictors for progression from AKI to advanced chronic kidney disease (CKD) stage.

METHODS

We analyzed clinical and pathological data of iMN with NS patients retrospectively collected from Jan 2012 to Dec 2018. The primary renal endpoint was defined as persistent eGFR <45ml/min per 1.73 m² more than 3 months. Comparisons of survival without primary renal endpoint were performed by Kaplan-Meier curves and log-rank test. Univariate and multivariate Cox proportional hazard models were constructed to determine independent variables associated with primary renal endpoint .

RESULTS

434 iMN with NS patients were enrolled. The incidence of AKI 1 stage, AKI 2 stage and AKI 3 stage was 23.1, 4.8 and 0.7% respectively. 66 (53.2%) patients with AKI had complete renal function recovery and 42 (33.9%) patients with AKI reached primary renal endpoint. Survival without primary renal endpoint was worse in AKI patients than No AKI patients (67.1 ± 5.3 and 43.7 ± 7.3% vs 99.5 ± 0.5 and 92.5 ± 4.2% at 2 and 4 years,p < 0.001). AKI was independently associated with primary renal endpoint, with an adjusted hazard ratio(HR) of 25.1 (95%CI 7.7-82.1, p < 0.001).

CONCLUSIONS

AKI was usually mild and overlooked in iMN patients with NS, but it had a strong association with poor clinical outcomes and was an independent risk factor for CKD progression.

Kidney Biopsy in Patients With Monoclonal Gammopathy: A Multicenter Retrospective Cohort Study

Objectives: To analyze the clinical characteristics and renal pathological manifestations of patients with monoclonal gammopathy (MG) and kidney injury. Methods: This was a multicenter retrospective cohort study conducted at four tertiary hospitals in China. The study population comprised patients with MG admitted from January 1 2013 to December 31 2020. Hospitalization records, laboratory data, and kidney biopsy reports of all patients were collected from the electronic hospital information systems. The study outcomes included kidney disease progression and major hemorrhagic complications after kidney biopsy. Results: We identified 1,164 patients with MG, 782 (67.2%) of whom had underlying kidney injury. Of 101 patients who underwent kidney biopsy, 16 had malignant neoplasms. Amyloid nephropathy was the most common finding (n = 34, 33.7%), followed by membranous nephropathy (n = 18, 17.8%) and membranoproliferative nephritis (n = 8, 7.9%). Among 85 patients with non-malignant hematologic conditions who underwent kidney biopsy, 43 had MG of renal significance (MGRS) related lesions and 42 had MG-unrelated lesions. The risk of kidney disease progression was higher in patients with kidney injury than in patients without kidney injury. Conclusion: Among patients with MG and kidney injury, only 12.9% underwent kidney biopsy and more than 40% of these patients had MG-unrelated lesions. A kidney biopsy is safe and essential to maximize the possibility of correct diagnosis for patients with clinically suspected MG of renal significance (MGRS).

Clinical and pathological analysis of renal biopsies of elderly patients in Northeast China: a single-center study

Purpose

To identify the clinical characteristics, histopathological features, and prognosis of kidney disease in a large cohort of elderly patients from Northeast China.

Methods

We retrospectively analyzed the renal disease spectrum in 7,122 patients who underwent renal biopsies at the Second Hospital of Jilin University from 2006 to 2020. Patients were grouped according to age: below 60 years (non-elderly group, n = 5923) and at least 60 years (elderly group, n = 1199). The clinical and pathological characteristics of renal biopsy patients in the groups were analyzed using the t-test and chi-square test.

Results

Compared with the non-elderly group, the elderly group had significantly fewer patients with primary glomerulonephritis, but more patients with tubulointerstitial disorders (p < .05). The incidence of IgA nephropathy, mesangial proliferative glomerulonephritis, and lupus nephritis was significantly lower in elderly patients than in non-elderly patients. The incidence of membranous nephropathy, membranoproliferative glomerulonephritis, diabetic nephropathy, hypertensive nephropathy, systemic vasculitis-associated renal damage, and amyloid nephropathy was significantly higher in elderly patients than in non-elderly patients (p < .05). The incidence of perinephric hematoma (≥4 cm²) in elderly patients with renal biopsy was lower than that in non-elderly patients. We noted that 79.9% of primary glomerulonephritis patients who received immunosuppressive therapy showed a remission rate of 83.5%.

Conclusion

The spectrum of kidney disease in the elderly is different from that in the younger population.

Clinicopathologic features and prognostic factors in older patients with biopsy-proven diabetic nephropathy

PURPOSE

The older population has increased sharply in China. However, renal clinical and histopathological data in this population are lacking. This study investigated the clinicopathologic features and the related risk factors for long-term renal survival in older patients with diabetic nephropathy (DN).

METHODS

In this retrospective observational study, 74 older patients (≥ 60 years old) with type 2 diabetes mellitus and biopsy-proven DN from 2007 to 2019 were included. Clinical data were extracted from electronic records. Renal biopsy specimens were semiquantitatively evaluated using the Renal Pathology Society (RPS) classification system. Cox proportional hazard analysis was used to estimate hazard ratios (HRs) for progression to end-stage renal disease (ESRD).

RESULTS

During the median follow-up period of 22 months, 24 (32%) older patients progressed to ESRD. Older patients who progressed to ESRD had poorer renal function, lower hemoglobin and albumin concentrations, more severe glomerular lesions, and higher percentages of Kimmelstiel-Wilson lesions than those who did not progress to ESRD. After adjusting for age, sex, baseline renal function, and pathological parameters, multivariate Cox proportional hazard analysis showed that RPS glomerular classification (HR 2.49, 95% confidence interval [CI] 1.03-6.04), estimated glomerular filtration rate (eGFR) (HR 0.76, 95% CI 0.58-0.99), and proteinuria (HR 3.85, 95% CI 1.44-10.27) were independent risk factors for progression to ESRD.

CONCLUSION

Lower eGFR, heavier proteinuria, and more severe RPS glomerular lesions were associated with ESRD in older patients with type 2 diabetes mellitus and DN.

Patients with Idiopathic Membranous Nephropathy: A Real-World Clinical and Economic Analysis of U.S. Claims Data

BACKGROUND

Membranous nephropathy (MN) is a common cause of nephrotic syndrome in nondiabetic adults. Approximately one third of patients with MN progress to end-stage renal disease (ESRD), while others may be successfully treated to remission. Patients with MN represent a high-risk population for whom management strategies can alter and improve outcomes. Currently, there is little real-world evidence regarding the burden of MN on health plans.

OBJECTIVES

To (a) characterize clinical and economic outcomes during a 1-year time frame among a prevalent cohort of patients with MN and (b) compare the 5% of patients incurring the highest cost with the remaining 95%.

METHODS

A retrospective analysis of commercially insured patients was conducted using MarketScan administrative health care claims data from January 1, 2012, to December 31, 2015. Patients were aged ≥ 18 years, enrolled In a fee-for-service plan, and had ≥ 2 medical claims for an MN diagnosis (ICD-9-CM codes 581.1, 582.1, and 583.1). Diagnoses indicating clear secondary causes were excluded wherever possible. Demographics were determined as of the first diagnosis date; clinical characteristics (e.g., MN-specific therapy, complications, and procedures), health care resource utilization (HCRU; inpatient, outpatient including other outpatient and emergency department [ED], and prescriptions), and costs were evaluated for 1 year following MN diagnosis. Total costs and cost distribution (2017 U.S. dollars) were examined using plan-paid and patient-paid amounts. The 95th percentile was used to categorize and compare the subcohorts: high-cost cohort (HCC) patients (top 5%) and non-high-cost cohort (NHCC) patients (the remaining 95%). Descriptive analyses, chi-square tests, and Wilcoxon rank-sum tests were conducted.

RESULTS

2,689 patients were identified (60.0% male, mean age = 46.4 years). Severity and advanced disease were observed In a higher proportion of HCC patients (n = 134) versus NHC patients (n = 2,555) via adverse health outcomes, procedures, and immunosuppressant use. HCC patients used significantly more resources on average than NHCC patients (additional use): 1.7 inpatient, 1.2 ED, and 4.8 outpatient office visits; 15 prescriptions; and 64.8 other outpatient visits (i.e., outpatient, hospital, and ESRD facilities). Total MN-related cost and mean (SD) cost per patient were $123.2 million and $45,814 ($101,353); HCC patients accounted for 43.7% of total costs for a mean cost per patient of $401,608 versus NHCC patients at 56.3% and mean cost per patient of $27,154. The greatest costs for both groups were related to outpatient visits (HCC = 46.7%; NHCC = 52.8%), inpatient visits (HCC = 27.7%; NHCC = 28.6%), and prescriptions (HCC = 25.7%; NHCC = 18.6%).

CONCLUSIONS

Patients with MN are significantly burdened with high disease severity and adverse health outcomes, resulting In substantial HCRU and costs. Health plan cost drivers for MN (HCC and NHCC patients) occurred primarily In the outpatient setting, followed by the inpatient setting and prescriptions. Modifiable aspects preceding progression to advanced renal disease and worse outcomes should be explored to Identify effective interventions and improve resource allocation earlier In the disease pathway, before ESRD.

DISCLOSURES

This study was funded by Mallinckrodt Pharmaceuticals. Kirkemo, Pavlova-Wolf, and Bartels-Peculis are employees and stockholders of Mallinckrodt Pharmaceuticals. Nazareth was an employee of Mallinckrodt Pharmaceuticals at the time of this study. Kariburyo, Xie, and Vaidya are employees of STATinMED Research, a paid consultant to Mallinckrodt Pharmaceuticals. Sim received an investigator-initiated research grant from Mallinkcrodt Pharmaceuticals. A portion of the study results were previously presented at the American Society of Nephrology (ASN) Kidney Week 2017; November 2, 2017; New Orleans, LA.

Clinical and Pathological Analysis of 4910 Patients Who Received Renal Biopsies at a Single Center in Northeast China

Purpose

To identify the epidemiology and pathological types of kidney diseases and their changes during the past decade, in a population from Northeast China.

Methods

We retrospectively analysed clinical and renal pathological data from 4910 patients who received renal biopsies in the Second Hospital of Jilin University from 2008 to 2017.

Results

Males received more renal biopsies than females (p < 0.001). The average age (p < 0.001) and percentage of elderly patients (p < 0.001) increased over time. The pathological types were primary glomerulonephritis (PGN, 73.2%), secondary glomerulonephritis (SGN, 23.7%), tubular-interstitial nephropathy (TIN, 2.8%), and hereditary nephropathy (HN, 0.3%). The most common forms of PGN were membranous nephropathy (MN, 37.2%) and IgA nephropathy (IgAN, 29.9%). Over time, the prevalence of IgAN decreased, but the prevalence of MN increased. MN was more common in middle-aged and elderly patients, but IgAN was most common in young adults. Analysis of SGN data indicated that lupus nephritis (LN, 34.0%), Henoch-Schönlein purpura glomerulonephritis (HSPN, 17.9%), and diabetic nephropathy (DN, 11.7%) were the most common forms. Over time, the prevalence of DN (p = 0.003), hypertension-associated renal damage (p = 0.005), and systemic vasculitis-associated nephritis (SVARD, p < 0.001) increased, but the prevalence of HSPN (p < 0.001) and hepatitis B virus-associated glomerulonephritis (HBV-GN, p = 0.001) decreased. Nephrotic syndrome was the main clinical manifestation of PGN.

Conclusion

From 2008 to 2017, renal biopsies were increasingly performed in the elderly. There were notable changes in the epidemiology and pathological types of kidney disease among renal biopsy patients at our centre.

Anti-LRP2 Nephropathy With Abundant IgG4-Positive Plasma Cells: A Case Report

In older adults, the most common kidney biopsy diagnoses include pauci-immune crescentic glomerulonephritis, membranous nephropathy, and focal segmental glomerulosclerosis. Recently, investigators described a small series of older patients (aged 66-80 years) with acute kidney injury and a kidney biopsy demonstrating tubular basement membrane (TBM) immune deposits of polytypic immunoglobulin G (IgG) and C3, acute tubular injury, and tubulointerstitial inflammation. They identified a circulating antibody against kidney tubular low-density lipoprotein (LDL) receptor-related protein 2 (LRP2; also known as megalin) in patients' sera and colocalization of LRP2 with IgG in TBM deposits. We present a rare case of anti-LRP2 nephropathy/anti-brush border antibody disease and describe the novel feature of abundant IgG4-positive interstitial plasma cells. Along with the combination of TBM deposits, tubulointerstitial nephritis (TIN), and segmental glomerular subepithelial immune deposits seen in both entities, this newly described feature adds to the morphologic overlap with IgG4-related TIN. Identification of large TBM deposits using light microscopy and IgG staining of apical aspects of proximal tubules using immunofluorescence microscopy can point to the correct diagnosis of anti-LRP2 nephropathy and prompt confirmatory studies. Particularly in older patients with immune complex-mediated TIN who lack clinical, laboratory, radiographic, and/or characteristic histologic features of IgG4-TIN or other autoimmune, infectious, or drug-related injury, a diagnosis of anti-LRP2 nephropathy should be considered.

Evaluation of kidney biopsies in elderly patients

OBJECTIVE

The renal parenchymal disease spectrum in geriatric patients is similar to that in younger patients and can be controlled by appropriate treatment. We evaluated the clinicopathological features of kidney biopsies from geriatric patients.

MATERIALS AND METHODS

One hundred nine native kidney biopsies from older patients (> 65 years old) obtained from 2005 to 2014 were evaluated retrospectively. The specimens were inspected by the same pathologist in the same laboratory by light microscopy and immunofluorescence.

RESULTS

The mean age of the patients was 72.4 ± 7.8 years (range 65-90 years), and 51.3% were female. The most frequent indication for kidney biopsy was proteinuria at the nephrotic level (56.8%). The most frequent histopathological diagnoses were focal segmental glomerulosclerosis in primary glomerulonephritis and secondary amyloidosis in secondary glomerulonephritis. The rate of major complications due to kidney biopsy was < 1%.

RESULT

Kidney biopsy is an effective and safe method of evaluating renal parenchymal diseases in older patients.

Changes in the diagnosis of glomerular diseases in east China: a 15-year renal biopsy study

Background: There have been some gradual changes in the distribution of renal biopsy pathological diagnoses during recent years. This study aimed to show changes in renal disease prevalence in China by investigating 10 patients diagnosed at our Kidney Disease Centre during the last 15 years.

Methods and results: All patients aged 15-year-old or older who underwent renal biopsy at the First Affiliated Hospital, Zhejiang University, from 2001 to 2015 were enrolled. There were 5 common types of primary glomerulonephritis: IgA nephropathy (IgA N), membranous nephropathy (MN), mesangial progressive glomerulonephritis (MsPGN), minimal change disease (MCD), and focal segmental glomerulosclerosis (FSGS), which represented 50%, 16.8%, 15.9%, 8.1% and 2.5% of total cases, respectively. IgA nephropathy was the most common type of primary glomerulonephritis (PGN).

Conclusions: Our results mostly showed a new trend that the diagnosis of IgA nephropathy was not increasing and the prevalence of membranous nephropathy had increased, becoming the second most common type of primary glomerulonephritis.

Key POINTS

Distinguished with other domestic studies, IgA nephropathy did not show a trend of continuous growth although it still had about the half proportion of PGN, whereas membranous nephropathy kept rising and became the second common PGN.

Concerning SGN, LN peaked in the younger-age and middle-age groups with a significant female prevalence, DN, BANS and SV had a male predominance peaking in the middle-age and old-age groups.

Causes of nephrotic syndrome and nephrotic-range proteinuria are different in adult Chinese patients: A single centre study over 33 years

AIM

The reported causes of nephrotic syndrome (NS) varies between different countries. Less is known about the causes of nephrotic-range proteinuria (NPU). We aimed to evaluate the underlying causes of NS and NPU.

METHODS

This was a single-centre, retrospective study of adult patients who underwent renal biopsy between 1983 and 2015 in a tertiary referral hospital in Hong Kong. We determined the distribution of histopathological diagnoses with regard to the age subgroups and time periods.

RESULTS

Among 7456 patients who underwent renal biopsy, 982 and 838 patients had NS and NPU, respectively. The most common diagnosis in NS was minimal change disease (MCD) (33.3%), followed by membranous nephropathy (MN) (23.6%) and lupus nephritis (LN) (12.8%); whereas the most common diagnosis in NPU was LN (27.4%), followed by immunoglobulin A nephropathy (IgAN) (21.4%) and diabetic nephropathy (DN) (9.3%). In the NS group, MCD was the most common diagnosis in young adults while MN was the leading cause in the elderly. On the other hand, LN was the most common pathology in the NPU group until the age of 60. Over the past three decades, there was a trend of decrease in the proportion of IgAN in both NS and NPU group, while a combined pathology of hypertensive nephrosclerosis and diabetic nephropathy (HTNS and DN) increased significantly.

CONCLUSIONS

The causes of NS and NPU in Chinese adults were different and may represent two distinct pathological identities. The spectrum of renal histopathology among these two groups changed significantly over time.

Elderly patients with glomerular diseases and IgA nephropathy

As the population ages, greater numbers of elderly patients will present with kidney diseases. Many kidney diseases, such as IgA nephropathy, will require kidney biopsy for diagnostic confirmation, treatment guidance and prognostication. In this paper, we review the current and expected future healthcare landscape with a focus on the ageing population, pros and cons of kidney biopsy in elderly patients, as well as treatment strategies and precautions. We also review the available data on IgA nephropathy in the elderly, including its occurrence rate based on the kidney biopsy, clinicohistopathological features, differentiation with IgA-dominant postinfectious glomerulonephritis, treatment options and outcome prediction. Overall, information on kidney diseases in patients with advanced age, including IgA nephropathy, is limited. Clinical evaluation and management strategies are extrapolated largely from studies in younger adults. Age-specific clinical and translational investigations of kidney diseases are eminently needed.

Patterns of renal disease in South Korea: a 20-year review of a single-center renal biopsy database

Background: Several registries and centers have reported the results of renal biopsies from different parts of the world. As there are few data regarding the epidemiology of glomerulonephritis (GN) in South Korea, we conducted this study on renal biopsy findings during the last 20 years from a single center.

Methods: Data for 818 patients who underwent renal biopsy at our center between 1992 and 2011 were collected retrospectively. All kidney specimens were examined with light microscopy (LM) and immunofluorescent microscopy (IF).

Results: There were 818 cases of native kidney biopsies. In cases of primary GN, the most frequent type of renal pathology in adults (18–59 years) was mesangial proliferative GN (MsPGN, 34.5%) followed by IgA nephropathy (IgAN, 33.3%) and membranous GN (MGN, 8.8%). Indications in adults (18–59 years) were asymptomatic urinary abnormalities (75.3%) followed by nephrotic syndrome (19.8%) and acute kidney injury (AKI, 3.4%).

Conclusions: Among 818 renal biopsy specimens, MsPGN and IgAN were the most frequent biopsy-proven renal diseases. MGN was the third most common cause of primary GN and lupus nephritis (LN) was the most common secondary glomerular disease. Our data contribute to the epidemiology of renal disease in South Korea.

Changes in the Spectrum of Kidney Diseases: An Analysis of 40,759 Biopsy-Proven Cases from 2003 to 2014 in China

Objectives

To evaluate the changing spectrum of kidney diseases over time in China using renal biopsy-proven cases.

Methods

All patients over the age of 14 years who were diagnosed with a kidney disease by renal biopsy in the Renal Biopsy Registry of the National Clinical Research Center of Kidney Diseases in Jinling Hospital, Nanjing, from 2003 to 2014 were included.

Results

In total, 40,759 cases of renal biopsy were analyzed. The mean age of the patients was 36.59 ± 14.12 years. 52.0$ of the patients were male. Primary glomerulonephritis (PGN), secondary glomerulonephritis, tubulointerstitial disease, and hereditary renal diseases accounted for 67.1, 26.4, 2.9, and 2.5$, respectively. IgA nephropathy (IgAN), membranous nephropathy (MN), minimal change disease, and focal segmental glomerulosclerosis were the leading PGN diagnoses. The frequency of MN increased significantly (p < 0.001) by doubling from 2003 to 2014. An analysis by age category indicated that the frequency of MN increased significantly over time (p < 0.001) in all age categories and increased by more than 2 times in the 14-24 age category. Lupus nephritis (LN) and Henoch-Schönlein purpura nephritis (HSPN) decreased significantly (p < 0.001), diabetic nephropathy (DN) increased nearly twice (p < 0.001), monoclonal immunoglobulin deposition disease (MIDD) tripled (p < 0.001), and hypertensive nephropathy (HT) (p < 0.001) and renal amyloidosis (AMY) (p < 0.05) showed an upward trend. An analysis by age category showed that hepatitis B-related nephritis has significantly decreased in the 14-24 age category (p < 0.001).

Conclusion

PGN continued to be the predominant kidney disease in China with IgAN being the most common PGN. The frequency of MN increased significantly, with a maximum increase in young adults. LN and HSPN decreased significantly, DN and MIDD increased significantly, and HT and AMY also showed an increasing trend. The kidney disease trends presented in this study serve as a reference point for patient care, disease prevention, and public health interventions.

Clinicopathologic correlations of renal pathology in the adult population of Poland

Background

This is the first report on the epidemiology of biopsy-proven kidney diseases in Poland.

Methods

The Polish Registry of Renal Biopsies has collected information on all (n = 9394) native renal biopsies performed in Poland from 2009 to 2014. Patients' clinical data collected at the time of biopsy, and histopathological diagnoses were used for epidemiological and clinicopathologic analysis.

Results

There was a gradual increase in the number of native renal biopsies performed per million people (PMP) per year in Poland in 2009-14, starting from 36 PMP in 2009 to 44 PMP in 2014. A considerable variability between provinces in the mean number of biopsies performed in the period covered was found, ranging from 5 to 77 PMP/year. The most common renal biopsy diagnoses in adults were immunoglobulin A nephropathy (IgAN) (20%), focal segmental glomerulosclerosis (FSGS) (15%) and membranous glomerulonephritis (MGN) (11%), whereas in children, minimal change disease (22%), IgAN (20%) and FSGS (10%) were dominant. Due to insufficient data on the paediatric population, the clinicopathologic analysis was limited to patients ≥18 years of age. At the time of renal biopsy, the majority of adult patients presented nephrotic-range proteinuria (45.2%), followed by urinary abnormalities (38.3%), nephritic syndrome (13.8%) and isolated haematuria (1.7%). Among nephrotic patients, primary glomerulopathies dominated (67.6% in those 18-64 years of age and 62.4% in elderly patients) with leading diagnoses being MGN (17.1%), FSGS (16.2%) and IgAN (13.0%) in the younger cohort and MGN (23.5%), amyloidosis (18.8%) and FSGS (16.8%) in the elderly cohort. Among nephritic patients 18-64 years of age, the majority (55.9%) suffered from primary glomerulopathies, with a predominance of IgAN (31.3%), FSGS (12.7%) and crescentic GN (CGN) (11.1%). Among elderly nephritic patients, primary and secondary glomerulopathies were equally common (41.9% each) and pauci-immune GN (24.7%), CGN (20.4%) and IgAN (14.0%) were predominant. In both adult cohorts, urinary abnormalities were mostly related to primary glomerulopathies (66.8% in younger and 50% in elderly patients) and the leading diagnoses were IgAN (31.4%), FSGS (15.9%), lupus nephritis (10.7%) and FSGS (19.2%), MGN (15.1%) and pauci-immune GN (12.3%), respectively. There were significant differences in clinical characteristics and renal biopsy findings between male and female adult patients.

Conclusions

The registry data focused new light on the epidemiology of kidney diseases in Poland. These data should be used in future follow-up and prospective studies.

Increasing prevalence of membranous nephropathy in patients with primary glomerular diseases: A cross-sectional study in China

AIM

Primary glomerular disease (PGD) remains the most common renal disease in China. A limited number of single centre studies show that the frequency of membranous nephropathy (MN) has increased; however, IgA nephropathy (IgAN) is still the most common PGD. To the best of our knowledge, there has been no multi-centre study in China that has explored the changes in PGD spectrum. To further investigate the changes in renal histopathological spectrum, we performed the cross-sectional study.

METHOD

From June 2010 to May 2015, 5935 patients from 37 hospitals in Shandong Province were involved in this retrospective study. The study was divided into five periods according to 1-year intervals. The patients were divided into four age groups (≤18 years, 19-44 years, 45-59 years and ≥60 years).

RESULT

Among the 5935 qualified specimens, 4855 (81.8%) were diagnosed with PGD. MN (43.3%) became the most common PGD instead of IgA (34.1%) (P < 0.001). The frequency of MN was increased from 30.7% in period 1 to 53.5% in period 5 (P < 0.001). The prevalence of MN tended to increase in every age section. IgA was the main cause of PGD in periods 1 and 2; however, its proportion decreased significantly from 41.8% in period 2 to 25.2% in period 5 (P < 0.001).

CONCLUSION

Primary glomerular disease remains the most common renal disease in our study. For the first time, this cross-sectional study suggests that MN, in place of IgAN, has grown to be the first leading pathological type of PGD.

Kidney disease in the elderly: biopsy based data from 14 renal centers in Poland

BACKGROUND

Longer life expectancy is associated with an increasing prevalence of kidney disease. Aging itself may cause renal damage, but the spectrum of kidney disorders that affect elderly patients is diverse. Few studies, mostly form US, Asia and West Europe found differences in the prevalence of some types of kidney diseases between elderly and younger patients based on renal biopsy findings, with varied proportion between glomerulopathies and arterionephrosclerosis as a dominant injury found. Here, for the first time in Eastern Europe we analyzed native kidney biopsy findings and their relationship to clinical characteristics at the time of biopsy in elderly individuals (aged ≥65) in comparison to younger adults (aged 18-64).

METHODS

Biopsy and clinical data from 352 patients aged ≥65 were retrospectively identified, analyzed and compared with a control group of 2214 individuals aged 18-64. All kidney biopsies studied were examined at Medical University of Warsaw in years 2009-14.

RESULTS

In elderly patients the leading indication for biopsy was nephrotic range proteinuria without hematuria (34.2%) and the most prevalent pathologic diagnoses were: membranous glomerulonephritis (MGN) (18.2%), focal segmental glomerulosclerosis (FSGS) (17.3%) amyloidosis (13.9%) and pauci immune glomerulonephritis (12.8%). Hypertension and age-related lesions very rarely were found an exclusive or dominant finding in a kidney biopsy (1.7%) and a cause of proteinuria (1.1%) in elderly individuals. There were 18.2% diabetics among elderly individuals, and as much as 75% of them had no morphologic signs of diabetic kidney disease in the renal biopsy. Amyloidosis, MGN, pauci immune GN, crescentic GN and light and/or heavy chain deposition disease (LCDD/HCDD) were more frequent whereas IgA nephropathy (IgAN), lupus nephritis (LN) and thin basement membrane disease (TBMD) were less common among elderly than in younger patients.

CONCLUSIONS

Proteinuria, a dominating manifestation in elderly patients subjected to kidney biopsy was most commonly related to glomerulopathies. The relatively high prevalence of potentially curative kidney diseases in elderly individuals implicates the importance of renal biopsy in these patients.

Identification of G8969>A in mitochondrial ATP6 gene that severely compromises ATP synthase function in a patient with IgA nephropathy

Here we elucidated the pathogenesis of a 14-year-old Chinese female who initially developed an isolated nephropathy followed by a complex clinical presentation with brain and muscle problems, which indicated that the disease process was possibly due to a mitochondrial dysfunction. Careful evaluation of renal biopsy samples revealed a decreased staining of cells induced by COX and NADH dehydrogenase activities, and a strong fragmentation of the mitochondrial network. These anomalies were due to the presence of a mutation in the mitochondrial ATP6 gene, G8969>A. This mutation leads to replacement of a highly conserved serine residue at position 148 of the a-subunit of ATP synthase. Increasing the mutation load in cybrid cell lines was paralleled by the appearance of abnormal mitochondrial morphologies, diminished respiration and enhanced production of reactive oxygen species. An equivalent of the G8969>A mutation in yeast had dramatic consequences on ATP synthase, with a block in proton translocation. The mutation was particularly abundant (89%) in the kidney compared to blood and urine, which is likely the reason why this organ was affected first. Based on these findings, we suggest that nephrologists should pay more attention to the possibility of a mitochondrial dysfunction when evaluating patients suffering from kidney problems.

Biopsy-proven kidney diseases in the elderly: clinical characteristics, renal histopathological spectrum and prognostic factors

Objective

To explore the clinical characteristics, renal histopathological spectrum and prognostic factors of biopsy-proven kidney diseases in the elderly.

Methods

A retrospective observational study was conducted in elderly patients who had received renal biopsies. Demographic, clinical and pathological data at the time of the biopsy were collected from the medical records. Follow-up records and prognostic factors were studied.

Results

The elderly (≥60 years) accounted for 74 of 434 (17.1%) native renal biopsies that were performed in a 9-year period. In the cohort of included elderly patients (n = 72), the prevalence of nephrotic syndrome and acute kidney injury was 62.5% (45 of 72) and 40.3% (29 of 72), respectively. For elderly patients with primary glomerular diseases (n = 44), membranous nephropathy was the most frequent pathological type (24 of 44; 54.5%). For elderly patients with secondary glomerular diseases (n = 25), anti-neutrophil cytoplasmic antibody-associated vasculitis was the most frequent aetiology (nine of 25; 36.0%). Requirement for renal replacement therapy (RRT) was an independent risk factor for poor prognosis.

Conclusions

Kidney diseases in the elderly have distinctive characteristics. Requirement for RRT was associated with poor prognosis in the elderly with biopsy-proven kidney diseases.

The Clinical Presentation and Management of Systemic Light-Chain Amyloidosis in China

BACKGROUND

Amyloidosis includes a group of diseases characterized by the extracellular deposition of various fibrillary proteins that can autoaggregate in a highly abnormal fibrillary conformation. The amyloid precursor protein of systemic light-chain (AL) amyloidosis is comprised of monoclonal light chains that are due to plasma cell dyscrasia. The clinical presentation of patients with AL amyloidosis varies from patient to patient. Current treatment strategies target the clone in order to decrease the production of the pathologic light chains. Recent advances in therapy have helped many patients with AL amyloidosis achieve hematologic and organ responses.

SUMMARY

AL amyloidosis is the most common type of systemic amyloidosis in China with increasing morbidity and a high mortality rate. The clinical presentation of AL amyloidosis is variable, and the median overall survival was found to be 36.3 months. The disease prognosis and risk stratification are linked to serialized measurement of cardiac biomarkers and free light chains. The treatment of AL amyloidosis is mainly based on chemotherapy and autologous hematopoietic stem cell transplantation (ASCT). The use of novel agents (thalidomide, lenalidomide, and bortezomib) alone and in combination with steroids and alkylating agents has shown efficacy and continues to be explored.

KEY MESSAGES

AL amyloidosis is the most common type of systemic amyloidosis in China with increasing morbidity and a high mortality rate. The lack of prospective clinical trials using the current therapies is a challenge for evidence-based decision making concerning the treatment of AL amyloidosis.

FACTS FROM EAST AND WEST

(1) AL amyloidosis is the most prevalent type of amyloidosis accounting for 65% of the amyloidosis-diagnosed patients in the UK and for 93% of the amyloidosis-diagnosed patients in China. The predisposition of men over women to develop AL amyloidosis might be higher in China than in Western countries (2:1 vs. 1.3:1). Both in the East and West, incidence increases with age. At the time of diagnosis, edema is twice as frequent and the proportion of renal involvement is higher in Chinese compared to Western patients. (2) Melphalan followed by ASCT is the current standard therapy but is restricted to eligible patients. The efficacy and safety of bortezomib combined with dexamethasone were proven in Western patients and recently confirmed in a Chinese cohort. Recent studies in China and the US indicate that bortezomib induction prior to ASCT increases the response rate. Thalidomide and lenalidomide have shown benefit, but toxicity and lack of clinical evidence exclude these agents from first-line therapy. The green tea extract epigallocatechin-3-gallate is under investigation as an inhibitor of AL amyloid formation and a compound that might dissolve amyloid.

Primary glomerular diseases in the elderly

Primary glomerular diseases in the elderly population are a frustrating topic due to difficulties in both the diagnosis and decision making about treatment. The most frequent type of primary glomerular disease in elderly is membranous nephropathy; while its counterpart in younger population is IgA nephropathy. The most frequent cause of nephrotic syndrome in the elderly is also membranous nephropathy. Pauci-immune crescentic glomerulonephritis (GN) rate increases both in elderly and very elderly population. Pauci-immune crescentic GNs should be regarded as urgencies in elderly patients as in their younger counterparts due to potential for causing end-stage renal disease in case of delayed diagnosis and treatment, and also causing mortality due to alveolar hemorrhage in patients with pulmonary involvement. Renal biopsy is the inevitable diagnostic method in the elderly as in all other age groups. Renal biopsy prevents unnecessary treatments and provides prognostic data. So advanced age should not be the sole contraindication for renal biopsy. The course of primary glomerular diseases may differ in the elderly population. Acute kidney injury is more frequent in the course and renal functions may be worse at presentation. These patients are more prone to be hypertensive. The decision about adding immune suppressive therapies to conservative methods should be made considering many factors like co-morbidities, drug side effects and potential drug interactions, risk of infection, patient preference, life expectancy and renal functions at the time of diagnosis.

Clinicopathological features of renal amyloidosis: a single-center study on 47 cases

The correlations between the clinicopathological features and the long-term outcomes of renal amyloidosis (RA) were analyzed with a view to develop strategies for improving diagnosis and prognosis of RA. We retrospectively reviewed the clinicopathological characteristics of 47 patients diagnosed with RA between 2004 and 2014 at the Wuhan Union Hospital. The data on the renal histology, clinical manifestations, and prognosis of RA patients were retrieved from the hospital records and characteristic patterns were identified. The histological changes in the kidneys were correlated with the clinical manifestations of RA. Additionally, most RA patients in this study had decreased serum levels of κ light chain and increased urine levels of κ and λ light chains as well as presence of M-protein in the urine and serum. Patients with early RA showed no specific pathognomonic symptoms. Bleeding associated with diagnostic renal biopsy was rare. We recommend that the routine work-up of patients aged over 40 years and presenting with non-diabetic nephropathy includes the non-invasive tests for the measurement of serum and urine levels of κ and λ light chains as well as protein electrophoresis tests for the presence of urinary and serum M-protein. Additionally, such patients should undergo renal biopsy screening with Cong-red staining to ensure early diagnosis of RA and improve their survival, since the risk of hemorrhage related to renal biopsy screening is low at early stages of RA.