ARF in children with minimal change nephrotic syndrome may be related to functional changes of the glomerular basal membrane

Efficacy and safety of rituximab for primary nephrotic syndrome with acute kidney injury: A two-center prospective cohort study

The purpose of this study was to investigate the efficacy and safety of a low-dose Rituximab (RTX) regimen driven by peripheral blood B lymphocyte count in the treatment of adult patients with nephrotic syndrome (NS) complicated with acute kidney disease (AKI). We conducted a prospective single-arm study to evaluate the effect of B cells-driven RTX regimen. Patients with NS (MCD, FSGS, MN, IgAN) complicated with AKI fulfilling the inclusion criteria were eligible for this study. Patients were followed up at intervals of 2 months. Student's t-test and Chi-squared test were used to analyze normally distributed continuous variables and non-normally distributed continuous variables, respectively. From August 2018 to January 2022, 23 patients met the inclusion criteria and agreed to participate in the study. 3, 9, and 11 patients were AKI stage 1, 2, and 3, respectively. From baseline to the latest follow-up, 20 patients had complete and partial recovery of renal function. Accompanied by depletion of B cells, significant reduction of urinary protein excretion, serum total cholesterol, and the number of relapses were observed during the 12 months after the first RTX infusion as compared with during the 12 months before RTX injection. The number of patients who maintained steroids and immunosuppressive medications also remarkably decreased. This study indicates that the targets-driven treatment of low-dose RTX can achieve a high remission rate and alleviate the loss of kidney function in treating NS with AKI. The long-term efficacy, side effects, and therapeutic economics of RTX are reasonable.

Clinical features of acute kidney injury in patients with nephrotic syndrome and minimal change disease: a retrospective, cross-sectional study

Background:

Minimal change nephropathy (MCD) is a common pathological type of nephrotic syndrome and is often associated with acute kidney injury (AKI). This study aimed to investigate the clinical characteristics and related factors of AKI in patients with MCD and nephrotic syndrome.

Methods:

Patients from Chinese People's Liberation Army General Hospital who were diagnosed with pathological renal MCD with clinical manifestations of nephrotic syndrome were included from January 1, 2013 to December 31, 2017. Patients diagnosed with membranous nephropathy (MN) by renal biopsy from January 1, 2013 to December 31, 2017 are included as a control population. We retrospectively analyzed the clinical and pathological characteristics of patients as well as the percentages and clinical characteristics of AKI in different age groups. We assessed the correlation of pathological characteristics with serum creatinine using multivariate linear regression analysis.

Results:

A total of 367 patients with MCD were included in the analysis, with a sex ratio of 1.46: 1 (male: female) and an age range of 6 to 77 years. Among all the patients, 109 developed AKI (29.7%), and of these patients, 85 were male (78.0%). In the 586 patients with MN, 27 (4.6%) patients developed AKI. The percentage of AKI in MCD patients was significantly higher than that in MN patients (χ² = 41.063, P < 0.001). The percentage of AKI increased with age in the MCD patients. The percentage of AKI in patients aged 50 years or older was 52.9% (46/87), which was significantly higher than that [22.5% (63/280)] in patients under 50 years (χ² = 6.347, P = 0.013). We observed statistically significant differences in age (43 [27, 59] years vs. 28 [20, 44] years, Z = 5.487, P < 0.001), male (78.0% vs. 51.4%, χ² = 22.470, P < 0.001), serum albumin (19.9 ± 6.1 g/L vs. 21.5 ± 5.7 g/L, t = 2.376, P = 0.018), serum creatinine (129.5 [105.7, 171.1] μmol/L vs. 69.7 [57.7, 81.9] μmol/L, Z = 14.190, P < 0.001), serum urea (10.1 [6.2, 15.8] mmol/L vs. 4.7 [3.6, 6.4] mmol/L, Z = 10.545, P < 0.001), IgE (266.0 [86.7, 963.0] IU/ml vs. 142.0 [35.3, 516.5] IU/ml, Z = 2.742, P = 0.007), history of diabetes (6.4% vs. 1.2%, P = 0.009), and history of hypertension (23.9% vs. 5.1%, χ² = 28.238, P < 0.001) between the AKI group and the non-AKI group. According to multivariate linear regression analysis, among the renal pathological features analyzed, renal tubular epithelial cell damage (β = 178.010, 95% CI: 147.888−208.132, P < 0.001) and renal interstitial edema (β = 28.833, 95% CI: 11.966−45.700, P = 0.001) correlated with serum creatinine values.

Conclusions:

The percentage of AKI in MCD patients is significantly higher than that in MN patients. Patients over 50 years old are more likely to develop AKI. Renal tubular epithelial cell injury and renal interstitial edema may be the main pathological lesions that are associated with elevated serum creatinine in patients with MCD.

Human albumin infusion for treating oedema in people with nephrotic syndrome

BACKGROUND

Oedema is a common clinical symptom in people with nephrotic syndrome and human albumin has been widely used in the treatment of oedema by increasing vascular volume and this inducing diuresis. It may be used with or without diuretics such as furosemide. However, the quantitative contribution of human albumin in treating oedema is not fully understood. If human albumin were found to be effective and safe in the treatment of oedema, it could help clinicians to develop therapeutic strategies to improve the management of diuretic resistance associated with nephrotic syndrome.

OBJECTIVES

This review aimed to examine the benefits and harms of human albumin infusion for treating oedema associated with nephrotic syndrome.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 23 June 2019 through contact with the Information Specialists using search terms relevant to this review. Studies in the Specialised Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and quasi-RCTs evaluating the effect of human albumin infusion compared with placebo or no intervention, human albumin with diuretics compared with diuretic alone, human albumin compared with diuretics and other treatments, clinical outcomes, death, quality of life, kidney function and adverse effects in people with nephrotic syndrome. We excluded cross-over studies but data for the first period was to be included if available.

DATA COLLECTION AND ANALYSIS

Standard methods of the Cochrane Collaboration were used. Two authors independently assessed eligibility, risk of bias, study quality and extracted data. We calculated mean difference (MD) for continuous data with 95% confidence intervals (CI). We assessed the certainty of the evidence using GRADE.

MAIN RESULTS

One study met our inclusion criteria (26 children with minimal change nephrotic syndrome) and 11 were excluded (nine cross-over studies, one where albumin was not used for nephrotic syndrome and one where authors did not state whether the children had oedema). Risk of bias for the included study was unclear for selection bias, high for performance and detection bias, low for attrition bias, and high for selective reporting. The included study compared albumin plus furosemide with an equal volume of dextrose. Of our prespecified outcomes, the authors reported clinical improvement as weight change, serum sodium and adverse outcomes (blood pressure). The authors reported a greater weight loss in the albumin treated group initially but no difference overall at 10 days. However, the data in the text and the figures were inconsistent so we could not confirm the authors statements (very low certainty evidence). It is uncertain whether albumin infusion improves serum sodium when compared with an equal volume of dextrose (MD 2.00 mEq/L, 95% CI -0.09 to 4.09), systolic blood pressure (MD 2.00 mmHg, 95% CI -3.52 to 7.52) or diastolic blood pressure (MD 2.00 mmHg, 95%CI -4.29 to 8.29). Death, quality of life, and kidney function were not reported.

AUTHORS' CONCLUSIONS

We identified only one small study that was relevant to our review, therefore we are unable to draw any conclusions regarding the use of human albumin with or without diuretics in nephrotic syndrome. More RCTs are needed.

Pathogenesis and Management of Acute Kidney Injury in Patients with Nephrotic Syndrome Due to Primary Glomerulopathies

Acute kidney injury in the context of nephrotic syndrome is a serious and alarming clinical problem. Largely, acute kidney injury is a relatively frequent complication among patients with comorbidities while it has been independently associated with an increased risk of adverse outcomes, including death and chronic kidney disease. Nephrotic syndrome, without hematuria or with minimal hematuria, includes a list of certain glomerulopathies; minimal change disease, focal segmental glomerulosclerosis and membranous nephropathy. In the light of primary nephrotic syndrome, pathophysiology of acute kidney injury is differentiated by the nature of the primary disease and the severity of the nephrotic state. This review aims to explore the clinical circumstances and pathogenetic mechanisms of acute kidney injury in patients with nephrotic syndrome due to primary glomerulopathies, focusing on newer perceptions regarding the pathogenesis and management of this complicated condition, for the prompt recognition and timely initiation of appropriate treatment in order to restore renal function to its baseline level. Prompt recognition of the precise cause of acute kidney injury is crucial for renal recovery. Clinical characteristics, laboratory and serological findings along with histopathological findings, if required, will reveal the implicated pathway leading to individualized approach and management.

Acute kidney injury complicating nephrotic syndrome of minimal change disease

Minimal change disease accounts for 70% to 90% of cases of nephrotic syndrome in children. It also causes nephrotic syndrome in adults, including patients older than age 60. Renal function is altered moderately in approximately 20% to 30% of patients because foot-process fusion impairs filtration of water and solutes. The glomerular filtration rate is reduced by approximately 20% to 30% and returns to baseline with remission of proteinuria. Over the past 50 years, a number of publications have reported cases of acute kidney injury occurring in approximately one-fifth to one-third of adult cases in the absence of prior or concomitant renal disease. Clinical attributes point to a male predominance, age >50, massive proteinuria, severe hypoalbuminemia, a background of hypertension and vascular lesions on kidney biopsy, along with ischemic tubular necrosis. Acute kidney injury may require dialysis for weeks or months until remission of proteinuria allows resolution of oliguria. In some cases, renal function does not recover. An effect of endothelin-1-induced vasoconstriction at the onset of proteinuria has been proposed to explain tubular cell ischemic necrosis. The main factors causing acute kidney injury in patients with minimal change disease are diuretic-induced hypovolemia and nephrotoxic agents. Acute kidney injury is uncommon in children in the absence of intercurrent complications. Infection, nephrotoxic medication, and steroid resistance represent the main risk factors. In all patients, the goal of supportive therapy is essentially to buy time until glucocorticoids obtain remission of proteinuria, which allows resolution of renal failure.

Urinary potassium to urinary potassium plus sodium ratio can accurately identify hypovolemia in nephrotic syndrome: a provisional study

There is evidence pointing to a decrease of the glomerular filtration rate (GFR) in a subgroup of nephrotic children, likely secondary to hypovolemia. The aim of this study is to validate the use of urinary potassium to the sum of potassium plus sodium ratio (UK/UK+UNa) as an indicator of hypovolemia in nephrotic syndrome, enabling detection of those patients who will benefit from albumin infusion. We prospectively studied 44 nephrotic children and compared different parameters to a control group (36 children). Renal perfusion and glomerular permeability were assessed by measuring clearance of para-aminohippurate and inulin. Vaso-active hormones and urinary sodium and potassium were also measured. Subjects were grouped into low, normal, and high GFR groups. In the low GFR group, significantly lower renal plasma flow (p = 0.01), filtration fraction (p = 0.01), and higher UK/UK+UNa (p = 0.03) ratio were noted. In addition, non-significant higher plasma renin activity (p = 0.11) and aldosteron (p = 0.09) were also seen in the low GFR group.

CONCLUSION

A subgroup of patients in nephrotic syndrome has a decrease in glomerular filtration, apparently related to hypovolemia which likely can be detected by a urinary potassium to potassium plus sodium ratio > 0.5-0.6 suggesting benefit of albumin infusion in this subgroup. What is Known: • Volume status can be difficult to assess based on clinical parameters in nephrotic syndrome, and albumin infusion can be associated with development of pulmonary edema and fluid overload in these patients. What is New: • Urinary potassium to the sum of urinary potassium plus sodium ratio can accurately detect hypovolemia in nephrotic syndrome and thus identify those children who would probably respond to albumin infusion.

Unique proximal tubular cell injury and the development of acute kidney injury in adult patients with minimal change nephrotic syndrome

Background

Adult patients with minimal change nephrotic syndrome (MCNS) are often associated with acute kidney injury (AKI). To assess the mechanisms of AKI, we examined whether tubular cell injuries unique to MCNS patients exist.

Methods

We performed a retrospective analysis of clinical data and tubular cell changes using the immunohistochemical expression of vimentin as a marker of tubular injury and dedifferentiation at kidney biopsy in 37 adult MCNS patients. AKI was defined by the criteria of the Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guidelines for AKI.

Results

Thirteen patients (35.1%) were designated with AKI at kidney biopsy. No significant differences in age, history of hypertension, chronic kidney disease, diuretics use, proteinuria, and serum albumin were noted between the AKI and non-AKI groups. Urinary N-acetyl-β-D-glucosaminidase (uNAG) and urinary alpha1-microglobulin (uA1MG) as markers of tubular injury were increased in both groups, but the levels were significantly increased in the AKI group compared with the non-AKI group. The incidence of vimentin-positive tubules was comparable between AKI (84.6%) and non-AKI (58.3%) groups, but vimentin-positive tubular area per interstitial area was significantly increased in the AKI group (19.8%) compared with the non-AKI group (6.8%) (p = 0.011). Vimentin-positive injured tubules with tubular simplification (loss of brush-border of the proximal tubule/dilated tubule with flattening of tubular epithelium) were observed in the vicinity of glomeruli in both groups, suggesting that the proximal convoluted tubules were specifically injured. Two patients exhibited relatively severe tubular injuries with vimentin positivity and required dialysis within 2 weeks after kidney biopsy. The percentage of the vimentin-positive tubular area was positively correlated with uNAG but not with uA1MG in the non-AKI group.

Conclusions

Proximal tubular injuries with increased uNAG exist in MCNS patients without renal dysfunction and were more severe in the AKI group than they were in the non-AKI group. The unique tubular injuries probably due to massive proteinuria might be a predisposing factor for the development of severe AKI in adult MCNS patients.

Single low-dose rituximab for the treatment of steroid-resistant nephrotic syndrome with acute kidney injury

The efficacy of rituximab for kidney disease, such as frequent relapsing nephrotic syndrome, has been reported recently. Herein, we report a case of a patient with acute kidney injury that was steroid-resistant nephrotic syndrome who responded to a single administration of low-dose rituximab. An 86-year-old Japanese woman with hypertension presented with severe peripheral edema within several days after onset. Due to the patient's age, renal biopsy was not performed, nephrotic syndrome was diagnosed and prednisolone was administered at 40 mg/day on the day after admission. However, anuria developed and hemodialysis was inevitably initiated on the 5th hospital day. The renal function did not recover, and the general condition gradually became aggravated. On the 50th hospital day, 100 mg rituximab was administered, which led to immediate depletion of CD20-positive cells. The urine volume gradually increased from 2-3 weeks after the rituximab administration, and the renal function recovered slightly. After 5 weeks, it became possible to wean the patient from dialysis, which had been applied for 3 months. Rituximab might be an option for the treatment of acute kidney injury due to steroid-resistant nephrotic syndrome.

Successful treatment of acute kidney injury in patients with idiopathic nephrotic syndrome using human atrial natriuretic Peptide

The acute onset of idiopathic nephrotic syndrome (NS) is often accompanied by acute kidney injury, which can lead to congestive heart failure and lung edema. In this report, we present two cases of NS-induced acute kidney injury successfully treated with a low dose of carperitide, a human atrial natriuretic peptide. In combination with standard diuretic therapy and immunotherapy, carperitide retained the renal function and spared the need for renal replacement therapy, including hemodialysis. Although further investigation in clinical trials is required to validate these findings, carperitide may be useful for maintaining the renal function in cases of NS-induced acute kidney injury.

Tacrolimus as rescue therapy for adult-onset refractory minimal change nephrotic syndrome with reversible acute renal failure

BACKGROUND

Some adult patients with minimal change nephrotic syndrome (MCNS) who are refractory to steroid treatment or combination with immunosuppressive drug developed reversible acute renal failure (ARF) due to persistent severe hypoalbuminemia and proteinuria. It is a challenge to find rescue therapies that are effective and safe in treating such difficult patients.

METHODS

In this prospective observational study, 13 patients with adult-onset MCNS, all unresponsive to treatment with a steroid or a steroid with other immunosuppressive drugs, were studied from January 2005 to February 2009. All patients developed ARF before enrollment. Oral tacrolimus (TAC) was started at 1 mg/day (target trough levels of 3-6 ng/mL) before serum creatinine (SCr) decreased to ≤133 μmol/L, and then increased doses were given (target trough level of 5-10 ng/mL) when SCr decreased to ≤133 μmol/L. Primary outcome variables were remission, and recovery from ARF. Secondary outcome variables were time to recovery from ARF, time to remission, relapse rate, changes in SCr and estimated glomerular filtration rate (eGFR).

RESULTS

One patient discontinued TAC due to deterioration of ARF, and 12 patients recovered from ARF. The mean time to recovery from ARF was 15.8 ± 4.4 days. Nine patients (69.2%) experienced complete remission (CR) and two patients (15.4%) experienced partial remission (PR). The mean time to PR and CR was 4.8 ± 2.7 and 9.4 ± 2.3 weeks, respectively. After a mean follow-up of 69.6 months, 36.4% (4/11) of patients who had remission experienced relapses. One patient who was resistant to TAC therapy had a doubling of serum creatinine concentration during follow-up.

CONCLUSIONS

TAC may be a suitable therapeutic option for treatment of adult-onset refractory MCNS with reversible ARF.

Acute kidney injury in adult idiopathic nephrotic syndrome

OBJECTIVE

This study aims to investigate the epidemiology, clinical and histological features, and prognosis of acute kidney injury (AKI) according to RIFLE classification in adult patients with idiopathic nephrotic syndrome.

METHODS

In this retrospective study, 277 patients with idiopathic nephrotic syndrome were reviewed from June 2005 to June 2009.

RESULTS

Fifty-one (18%) patients entered RIFLE class Risk (AKI-R); 24 (9%) patients entered RIFLE class Injury (AKI-I); and 20 (7%) patients entered RIFLE class Failure (AKI-F). Logistic regression analysis showed that severe hypoalbuminemia, increase in age, and being male were risk factors of AKI. Cumulative recovery rates in 3 months for groups AKI-R, AKI-I, and AKI-F were 95%, 100%, and 94%, respectively (p  =  0.21). The mean time to recovery for groups AKI-R, AKI-I, and AKI-F was 20 ± 3, 25 ± 4, and 30 ± 5 days, respectively. Cumulative complete remission rates in 3 months for groups AKI-R, AKI-I, and AKI-F were 92%, 86%, and 65%, respectively (p  =  0.002). The mean time to remission for groups AKI-R, AKI-I, and AKI-F was 28 ± 3, 39 ± 6, and 62 ± 8 days, respectively.

CONCLUSION

AKI is not uncommon in adult idiopathic nephrotic syndrome. More severe AKI was associated with longer time of nephrotic syndrome complete remission. Renal function can recover completely in most of the patients.

Minimal mesangial lupus nephritis: a systematic review

OBJECTIVES

To summarize the clinical presentation, histological features, treatment, and outcome of minimal change nephropathy (MCN) in patients with systemic lupus erythematosus (SLE).

METHODS

We performed a systematic review of cases of MCN in SLE patients reported in the English literature from January 1985 to May 2009 by a Medline search.

RESULTS

The estimated prevalence of MCN in biopsy-proven lupus nephritis is 2.3% in childhood and 1.1% in adults. There are 13 individual cases (12 women, one man) of SLE-related MCN reported in the literature. The mean age of nephritis onset was 32.7 years. In six (46%) patients, MCN was the initial manifestation of SLE. All patients presented with nephrotic syndrome and two (15%) had active urinary sediments. Renal function was impaired in eight (62%) patients and six (46%) patients had active lupus serology. All patients responded promptly to high-dose glucocorticoids but four (31%) had relapse of proteinuria during their course of SLE. None of the patients developed thromboembolic or infective complications.

CONCLUSIONS

MCN is an uncommon histological class of lupus nephritis. Typically, patients present with heavy proteinuria, and transient renal dysfunction is common. The prognosis of MCN in SLE appears to be good because of its rapid response to glucocorticoids. Relapses of proteinuria may be reduced by the use of maintenance immunosuppression. Alkylating agents, calcineurin inhibitors, mycophenolate mofetil, and rituximab can be considered in glucocorticoid-dependent or refractory cases of SLE-related MCN.

Randomized cross-over trial comparing albumin and frusemide infusions in nephrotic syndrome

The contribution of hypoalbuminemia to impaired diuretic responsiveness can be overcome by administering larger doses of loop diuretics. However, the clinical efficacy of the combination of loop-acting diuretics with human albumin remains controversial. In the study reported here, 16 children with nephrotic syndrome and refractory edema were randomized in a cross-over trial to receive either the combination of 20% human albumin and frusemide infusion (HA+FU infusion group) or frusemide infusion alone (FU infusion group). At the end of study, median urine volume was 3.27 [95% confidence interval (CI) 2.04-4.50] ml/kg per hour in the HA+FU infusion group and 1.33 (95% CI 0.79-1.88) ml/kg per hour in the FU infusion group (P = 0.01); the median daily sodium excretion was 58 (95% CI 30-366) mEq and 30 (95% CI 10-122) mEq (P = 0.08), respectively The changes in other variables included weight loss [HA+FU 5.2% (95% CI 3.1-8.8); FU 0.8% (95% CI -1.9 to 4.1); P = 0.006]; urine osmolality [HA+FU 315 (95% CI 220-426) mOsm/kg; FU 368 (95% CI 318-446) mOsm/kg; P = 0.13]; osmolal clearance [HA+FU 1600 (95% CI 916-4140) ml/day; FU 880 (95% CI 510-2105) ml/day; P = 0.01; free water clearance [HA+FU -190 (95% CI -960 to 280) ml/day; FU -162 (95% CI -446 to -70) ml/day; P = 0.18]. The findings from this study suggest that the co-administration of albumin and frusemide infusions is more effective than the administration of frusemide infusion alone in inducing diuresis and natriuresis in patients with nephrotic syndrome.

Increased endothelin 1 expression in adult-onset minimal change nephropathy with acute renal failure

BACKGROUND

Acute renal failure (ARF) occurs in some adult patients with minimal change nephropathy (MCN). To investigate clinical and pathological factors associated with developing ARF, we compared clinical features and kidney pathological characteristics of endothelin 1 (ET-1) expression in patients with adult-onset MCN with and without ARF.

METHODS

The patient population consisted of 53 patients consecutively diagnosed with adult-onset MCN during a 10-year period. Based on creatinine clearance, 25 patients were assigned to the ARF group and 28 patients were assigned to the non-ARF group.

RESULTS

Clinical data show that the ARF group had a higher blood pressure, higher serum cholesterol level, and lower serum albumin level than the non-ARF group. Pathological data showed more severe foot-process effacement, interstitial edema, and flattened tubular epithelium in the same group. Greater ET-1 expression was detected in vessels, tubules, and glomeruli of the ARF compared with non-ARF group. The ARF group experienced a lower steroid response rate. However, there was no significant difference in stability of remission to steroid treatment in patients who achieved a remission.

CONCLUSION

ARF associated with enhanced kidney ET-1 expression is a reversible complication of MCN that occurs frequently in patients with apparently expanded extracellular fluid. Presumptively, ARF may develop as an amplification of the underlying pathogenesis of MCN involved in enhanced ET-1 expression, which may be superimposed by a transient episode of circulatory insufficiency during diuretic treatment.