Nephrotic syndrome disease activity is proportional to its associated hypercoagulopathy

Native nephrectomy in advanced pediatric kidney disease: indications, timing, and surgical approaches

In pediatric kidney failure, native kidneys may pose a risk to successful transplant outcomes. The indications and timing of native nephrectomy represent a controversial management decision. A lack of high-quality, outcomes-based data has prevented development of evidence-based guidelines for intervention. In this article, we review the published literature on medical indications for native nephrectomy and current knowledge gaps. In addition, we provide a surgical perspective regarding timing and approach.

Prothrombin Knockdown Protects Podocytes and Reduces Proteinuria in Glomerular Disease

Chronic kidney disease (CKD) is a leading cause of death, and its progression is driven by glomerular podocyte injury and loss, manifesting as proteinuria. Proteinuria includes urinary loss of coagulation zymogens, cofactors, and inhibitors. Importantly, both CKD and proteinuria significantly increase the risk of thromboembolic disease. Prior studies demonstrated that anticoagulants reduced proteinuria in rats and that thrombin injured cultured podocytes. Herein we aimed to directly determine the influence of circulating prothrombin on glomerular pathobiology. We hypothesized that (pro)thrombin drives podocytopathy, podocytopenia, and proteinuria. Glomerular proteinuria was induced with puromycin aminonucleoside (PAN) in Wistar rats. Circulating prothrombin was either knocked down using a rat-specific antisense oligonucleotide or elevated by serial intravenous infusions of prothrombin protein, which are previously established methods to model hypo- (LoPT) and hyper-prothrombinemia (HiPT), respectively. After 10 days (peak proteinuria in this model) plasma prothrombin levels were determined, kidneys were examined for (pro)thrombin co-localization to podocytes, histology, and electron microscopy. Podocytopathy and podocytopenia were determined and proteinuria, and plasma albumin were measured. LoPT significantly reduced prothrombin colocalization to podocytes, podocytopathy, and proteinuria with improved plasma albumin. In contrast, HiPT significantly increased podocytopathy and proteinuria. Podocytopenia was significantly reduced in LoPT vs. HiPT rats. In summary, prothrombin knockdown ameliorated PAN-induced glomerular disease whereas hyper-prothrombinemia exacerbated disease. Thus, (pro)thrombin antagonism may be a viable strategy to simultaneously provide thromboprophylaxis and prevent podocytopathy-mediated CKD progression.

Thromboembolic phenomena in patients with nephrotic syndrome: pathophysiology, risk factors, prophylaxis and treatment

Thromboembolic events resulting from disturbances in the body's balance of thrombotic and antithrombotic abilities are among the most life-threatening complications of nephrotic syndrome. Certain causes of nephrotic syndrome leave the patient particularly susceptible to thromboembolism. The severity of proteinuria and degree of hypoalbuminaemia are other common predictors of risk. Timely initiation of prophylactic therapy can help prevent morbidity and mortality associated with this complication in patients with nephrotic syndrome. The duration of treatment and choice of therapeutic agent depends on several factors, including the degree of hypoalbuminaemia, risk factors for thrombosis and risk of bleeding. This article reviews current understanding of the pathophysiology and risk factors for thromboembolism associated with nephrotic syndrome, and summarises recommendations and strategies for preventing and treating thromboembolic events in patients with nephrotic syndrome.

Nephrotic syndrome: pathophysiology and consequences

In patients with kidney disease, nephrotic syndrome can lead to several complications including progressive kidney dysfunction. Proteinuria may lead to the formation of cellular or fibrous crescents with reciprocal development of rapidly progressive glomerulonephritis or focal glomerulosclerosis. Proteinuria may also cause overload and dysfunction of tubular epithelial cells, eventually resulting in tubular atrophy and interstitial fibrosis. Hypoalbuminemia is usually associated with increased risk of mortality and kidney dysfunction. Dyslipidemia may increase the risk of atherosclerotic complications, cause podocyte dysfunction and contribute to vascular thrombosis. Urinary loss of anticoagulants and overproduction of coagulation factors may facilitate a hypercoagulable state. Edema, hypogammaglobulinemia, loss of complement factors, and immunosuppressive therapy can favor infection. Treatment of these complications may reduce their impact on the severity of NS. Nephrotic syndrome is a kidney disorder that can worsen the quality of life and increase the risk of kidney disease progression.

Exploring the Role of Antithrombin in Nephrotic Syndrome-Associated Hypercoagulopathy: A Multi-Cohort Study and Meta-Analysis

BACKGROUND

Nephrotic syndrome is associated with an acquired hypercoagulopathy that is thought to drive its predisposition for venous thromboembolism. Previous studies have suggested that urinary antithrombin (AT) loss leading to acquired AT deficiency is the primary mechanism underlying this hypercoagulopathy, but this hypothesis has not been directly tested. The objectives of this study were to test the influence of AT levels on hypercoagulopathy in nephrotic syndrome patient samples and perform meta-analyses to evaluate the likelihood of AT deficiency in patients with nephrotic syndrome.

METHODS

Samples from three independent nephrotic syndrome cohorts were analyzed. AT antigen and activity assays were performed using ELISA and amidolytic assays, respectively. Plasma thrombin generation, albumin, and urine protein-to-creatinine ratios were determined using established methods. Meta-analyses were performed by combining these new data with previously published data.

RESULTS

AT levels were not consistently related to either plasma albumin or proteinuria. AT was quantitatively related to hypercoagulopathy in adult nephrotic syndrome, whereas AT activity was inconsistently associated with hypercoagulopathy in childhood nephrotic syndrome. Notably, hypercoagulopathy did not differ between patients with normal AT levels and those with levels below the threshold used to define clinical AT deficiency (<70%). Moreover, ex vivo AT supplementation did not significantly alter hypercoagulopathy in AT-deficient plasma samples. The meta-analyses demonstrated that AT deficiency was not a uniform feature of nephrotic syndrome and was more common in children than adults.

CONCLUSIONS

These data suggest that AT deficiency plays only a limited role in the mechanisms underlying the acquired hypercoagulopathy of nephrotic syndrome. Moreover, AT deficiency was not present in all patients with nephrotic syndrome and was more likely in children than adults despite the higher risk for venous thromboembolism in adults than children.

Successful Pulmonary Endarterectomy after Acute Pulmonary Embolism and Reversal of Acute Cor Pulmonale in an 11-Year-Old Boy with Nephrotic Syndrome

Patients with nephrotic syndrome (NS) are at an increased risk for thromboembolic events, such as deep venous and arterial thrombosis and pulmonary embolism (PE). In general, PE in children differs from adults in incidence, predisposition, pathophysiology, presenting symptoms, and management strategies. There is a lack of treatment guidelines for PE in children, and the management strategies are mostly extrapolated from adult data. This case report highlights the presentation of acute cor pulmonale due to massive PE associated with NS and a successful pulmonary endarterectomy that reversed the child’s pulmonary hypertension and normalized right ventricular function.

Aberrant Expression of SIRT6 and VNN1 in Peripheral Blood Monocytes of Children with Primary Nephrotic Syndrome and Its Diagnostic and Prognostic Values

Objective

The objective is to explore the aberrant sirtuin-6 (SIRT6) and Vanin-1 (VNN1) protein expression in peripheral blood monocytes (PBM) of children with primary nephrotic syndrome (PNS) and its diagnostic and prognostic values.

Methods

83 child patients with nephrotic syndrome (NS) and 65 healthy volunteers were enrolled in the study. The test of SIRT6 and VNN1 was performed by the Western blot. The receiver operator characteristic (ROC) curve was used to analyze the diagnostic and prognostic value of SIRT6 and VNN1 for child patients with NS. The logistic regression was used to analyze the association of SIRT6 and VNN1 with the prognosis of NS child patients.

Results

SIRT6 in monocytes in the study group was inferior versus the control, while VNN1 outweighed it. The AUC of the combined detection of SIRT6 and VNN1 for the diagnosis of NS was 0.854, with a sensitivity of 80.0% and a specificity of 80.7%. The AUC of combined detection of SIRT6 and VNN1 for the prognosis of NS was 0.860, with a sensitivity of 84.6% and a specificity of 79.2%. The logistic regression analysis showed that less than 21.09 in SIRT6 was the number of risk factors for the prognosis of NS child patients (P < 0.05).

Conclusion

SIRT6 and VNN1 are provided with diagnostic and prognostic values for NS.

The diagnostic value of native kidney biopsy in low grade, subnephrotic, and nephrotic range proteinuria: A retrospective cohort study

Background

In nephrotic range proteinuria of adult-onset, kidney biopsy is the diagnostic gold standard in determining the underlying cause of disease. However, in low grade or subnephrotic proteinuria the diagnostic value of kidney biopsy as first-line diagnostics is less well established.

Methods

We conducted a retrospective analysis of all native kidney biopsies at our institution (n = 639) between 01/2012 and 05/2021 for comparison of histological diagnoses and clinical outcomes stratified by amount of proteinuria at the time of kidney biopsy: A: <300mg/g creatinine (low grade), B: 300-3500mg/g creatinine (subnephrotic), C >3500mg/g creatinine (nephrotic).

Results

Nephrotic range proteinuria was associated with the highest frequency (49.3%) of primary glomerulopathies followed by subnephrotic (34.4%) and low grade proteinuria (37.7%). However, within the subnephrotic group, the amount of proteinuria at kidney biopsy was linearly associated with renal and overall survival (HR 1.05 per Δ100mg protein/g creatinine (95% CI: 1.02–1.09, p = 0.001)) independent of present histological diagnoses and erythrocyturia.

Conclusion

Frequency of primary glomerulopathies supports to perform kidney biopsy in patients with subnephrotic proteinuria. These patients have a substantial risk of ESKD and death upon follow-up. Therefore, diagnostic accuracy including histopathology is essential to guide personalized treatment and avert detrimental courses.

Clinical presentation and management of nephrotic syndrome in the first year of life: A report from the Pediatric Nephrology Research Consortium

BACKGROUND AND OBJECTIVES

Nephrotic syndrome (NS) in the first year of life is called congenital (CNS) if diagnosed between 0-3 months, or infantile (INS) if diagnosed between 3-12 months of age. The aim of this study was to determine if there were clinically meaningful differences between CNS and INS patients, regarding clinical presentation, management and outcomes.

DESIGN SETTING PARTICIPANTS AND MEASUREMENTS

Eleven Pediatric Nephrology Research Consortium sites participated in the study, using IRB-approved retrospective chart reviews of CNS and INS patients born between 1998 and 2019. Data were collected on patient characteristics, pertinent laboratory tests, provided therapy, timing of unilateral/bilateral nephrectomy and initiation of renal replacement therapy (RRT).

RESULTS

The study included 69 patients, 49 with CNS and 20 with INS, with a median age at diagnosis of 1 and 6 months, respectively. Management for the two groups was similar regarding nutrition, thyroxin supplementation, immunoglobulin administration, and thrombosis prophylaxis. Within the first 2 months after diagnosis, daily albumin infusions were used more often in CNS vs. INS patients (79 vs. 30%; p = 0.006), while weekly infusions were more common in INS patients (INS vs. CNS: 50 vs. 3%; p = 0.001). During the 6 months preceding RRT, albumin infusions were more frequently prescribed in CNS vs. INS (51 vs. 15%; p = 0.007). Nephrectomy was performed more often in CNS (78%) than in INS (50%; p = 0.02). End-stage kidney disease tended to be more common in children with CNS (80%) vs. INS (60%; p = 0.09).

CONCLUSION

Compared to INS, patients with CNS had a more severe disease course, requiring more frequent albumin infusions, and earlier nephrectomy and RRT. Despite center-specific variations in patient care, 20-40% of these patients did not require nephrectomy or RRT.