Complications of the nephrotic syndrome and their treatment

Association of eGFR and Albuminuria with Venous Thromboembolism

BACKGROUND

CKD has been implicated as a risk factor of venous thromboembolism, but the evidence is limited to relatively healthy populations. The objective of this study was to discern whether parameters of kidney function and damage are associated with the occurrence of venous thromboembolism after hospitalization.

METHODS

We conducted a retrospective study including 23,899 and 11,552 adult individuals hospitalized within Geisinger Health System and New York University (NYU) Langone Health from 2004 to 2019 and 2012 to 2022, respectively. A Poisson model was used to evaluate adjusted incidence rates of venous thromboembolism according to eGFR and albuminuria categories in each cohort. Cox proportional hazards models were used to analyze associations of eGFR and urinary albumin-to-creatinine ratio (UACR) with venous thromboembolism, and hazard ratios (HRs) were meta-analyzed across cohorts.

RESULTS

Both lower eGFR and higher UACR were associated with higher risks of venous thromboembolism. In the Geisinger cohort, the incidence of venous thromboembolism after hospital discharge ranged from 10.7 (95% confidence interval [CI], 9.2 to 12.6) events per 1000 person-years in individuals in G1A1 (eGFR >90 ml/min per 1.73 m 2 and UACR <30 mg/g) to 27.7 (95% CI, 20.6 to 37.2) events per 1000 person-years in individuals with G4-5A3 (eGFR <30 ml/min per 1.73 m 2 and UACR >300 mg/g). A similar pattern was observed in the NYU cohort. Meta-analyses of the two cohorts showed that every 10 ml/min per 1.73 m 2 reduction in eGFR below 60 ml/min per 1.73 m 2 was associated with a 6% higher risk of venous thromboembolism (HR 1.06 [95% CI, 1.02 to 1.11], P = 0.01), and each two-fold higher UACR was associated with a 5% higher risk of venous thromboembolism (HR 1.05 [95% CI, 1.03 to 1.07], P < 0.001).

CONCLUSIONS

Both eGFR and UACR were independently associated with higher risk of venous thromboembolism after hospitalization. The incidence rate was higher with greater severity of CKD.

PODCAST

This article contains a podcast at https://dts.podtrac.com/redirect.mp3/www.asn-online.org/media/podcast/CJASN/2023_12_14_CJN0000000000000352.mp3.

Relationship of Thyroid Function with Renal Hemodynamics and Cholesterol Metabolism in Proteinuric Kidney Disease: A Pilot Study

Nephrotic syndrome and hypothyroidism are respectively reported to influence renal hemodynamics and hypercholesterolemia. However, the relationship of proteinuria-associated thyroid function with renal hemodynamics and cholesterol metabolism has yet to be determined in a simultaneous analysis of thyroid, renal, and cholesterol variables. We investigated the hypothesis that the changes in thyroid hormones by proteinuria may contribute to changes in cholesterol metabolism and renal hemodynamics by proteinuria. Twenty-nine patients (17 men and 12 women) with proteinuric kidney disease (mean age 46 years) were enrolled in a pilot study. Data for serum free triiodothyronine (FT3), free thyroxine (FT4), total cholesterol, and filtration fraction (FF; assessed by para-aminohippuric acid clearance) were used in variable-adjusted correlation analyses. The patients had the following data (mean ± standard deviation): urinary protein 5.18 ± 3.28 g/day, FT3 2.18 ± 0.44 pg/mL, FT4 1.03 ± 0.26 ng/dL, FF 0.27 ± 0.07, and total cholesterol 327 ± 127 mg/dL. There was a significant positive correlation of FT3 with FF (β = 0.58, p = 0.01) and a significant inverse correlation of FT4 with total cholesterol (β = -0.40, p = 0.01). A positive correlation of FT3 with FF and an inverse correlation of FT4 with total cholesterol were demonstrated in patients with proteinuric kidney disease. The proteinuria-associated reduction in serum thyroid hormone levels was correlated with hypercholesterolemia and the reduced glomerular FF. Further studies of these relationships are required.

A patient with spontaneous bilateral renal vein thrombosis but no risk factors

INTRODUCTION AND IMPORTANCE

Spontaneous bilateral renal vein thrombosis is a rare condition, especially when the patient has no risk factors.

CASE PRESENTATION

In this report, we describe a patient with bilateral renal vein thrombosis who presented with severe flank pain, renal functions remained normal, and the thrombus resolved completely with anticoagulation. There is no history of hypercoagulable condition in our patient. A one-year followup with CT angiogram revealed that the kidney was functioning normally and that the thrombus in the renal veins had completely resolved.

CLINICAL DISCUSSION

Management of an acute renal vein thrombosis depends upon whether the patient presents with acute kidney injury. In general, patients without acute kidney injury can be treated with therapeutic anticoagulation, whereas those with acute kidney injury should undergo dissolution or removal of the thrombus with thrombolytic therapy with or without thrombectomy.

CONCLUSION

Diagnosis of spontaneous renal vein thrombosis requires a high index of suspicion. Patient can be managed with therapeutic anticoagulation if renal function is intact. If thrombolysis and/or thrombectomy are performed on time, kidney function can be fully restored.

Biological drugs for systemic lupus erythematosus or active lupus nephritis and rates of infectious complications. Evidence from large clinical trials

Systemic lupus erythematosus (SLE) is a multisystemic autoimmune disease that frequently affects the kidneys, known as lupus nephritis (LN). Such patients are treated with antimalarials, corticosteroids or immunosuppressive drugs, and more recently, target-specific biological drugs. Although efficacy of these therapies improved SLE-related outcomes, SLE remains associated with higher rates of infections. Here, we performed a comprehensive systemic review of infectious complications in clinical trials covering drug interventions for SLE or specifically for active LN. Our search in 15 online registries yielded a total of 1477 studies of which 14 matched our prespecified criteria. These covered the biological drugs anifrolumab, belimumab, and rituximab that were tested in patients with non-renal SLE and active LN.The available safety data from the SLE trials indicated that infectious complications such as herpes zoster, upper respiratory tract infection, nasopharyngitis, bronchitis, and urinary tract infection in patients receiving placebo were quite prevalent especially in the EXPLORER (rituximab) trial. Infections occurred mostly during the first year of LN therapy. Serious adverse events and infectious complications occurred more frequently in placebo-treated patients with active LN, especially in the BLISS-LN (belimumab) and LUNAR (rituximab) trials. Anifrolumab and rituximab increased the number of clinically relevant episodes of herpes zoster compared to belimumab in patients with active LN. Anifrolumab displayed a similar trend for influenza infections, which is consistent with the specific mechanisms-of-action of anifrolumab; highlighting drug-specific effects on infectious complications. In addition, standard-of-care therapy, e.g., MMF and immunosuppressants, as well as a longer SLE duration may also affect the incidence of serious adverse events and certain infectious complications in SLE patients with active LN.Infectious complications are common in SLE but even more common in patients with active LN, especially herpes zoster is strongly associated with active LN and anifrolumab therapy (OR 2.8, 95% CI 1.18 to 6.66, p = 0.018). Immunotherapy seems to impose unspecific and specific risks for infections. The latter may imply specific precautions such as preemptive vaccination and individual risk-benefit assessments.

Risk of Arterial Thromboembolism, Venous Thromboembolism, and Bleeding in Patients with Nephrotic Syndrome: A Population-Based Cohort Study

BACKGROUND

Although venous thromboembolism is a well-known complication of nephrotic syndrome, the long-term absolute and relative risks of arterial thromboembolism, venous thromboembolism, and bleeding in adults with nephrotic syndrome remain unclarified.

METHODS

In this matched cohort study, we identified every adult with first-time recorded nephrotic syndrome from admissions, outpatient clinics, or emergency department visits in Denmark during 1995-2018. Each patient was matched by age and sex with 10 individuals from the general population. We estimated the 10-year cumulative risks of recorded arterial thromboembolism, venous thromboembolism, and bleeding accounting for the competing risk of death. Using Cox models, we computed crude and adjusted hazard ratios (HRs) of the outcomes in patients with nephrotic syndrome versus comparators.

RESULTS

Among 3967 adults with first-time nephrotic syndrome, the 1-year risk of arterial thromboembolism was 4.2% (95% confidence interval [CI] 3.6-4.8), of venous thromboembolism was 2.8% (95% CI 2.3-3.3), and of bleeding was 5.2% (95% CI 4.5-5.9). The 10-year risk of arterial thromboembolism was 14.0% (95% CI 12.8-15.2), of venous thromboembolism 7.7% (95% CI 6.8-8.6), and of bleeding 17.0% (95% CI 15.7-18.3), with highest risks of ischemic stroke (8.1%), myocardial infarction (6.0%), and gastrointestinal bleeding (8.2%). During the first year, patients with nephrotic syndrome had increased rates of both arterial thromboembolism (adjusted HR [HR_adj] = 3.11 [95% CI 2.60-3.73]), venous thromboembolism (HR_adj = 7.11 [5.49-9.19]), and bleeding (HR_adj = 4.02 [3.40-4.75]) compared with the general population comparators after adjusting for confounders.

CONCLUSION

Adults with nephrotic syndrome have a high risk of arterial thromboembolism, venous thromboembolism, and bleeding compared with the general population. The mechanisms and consequences of this needs to be clarified.

Association between diuretic administration before diagnosis and incidence of acute kidney injury in patients with minimal change disease: A single-center observational study

We examined the association between diuretic administration before the diagnosis of minimal change disease and the incidence of acute kidney injury. Moreover, we examined whether the use of diuretics affected the time to complete remission in adults with such disease.The present study was a single-center, retrospective, observational cohort study. We included 107 patients with biopsy-proven minimal change disease who were treated at a tertiary referral center in Japan between January 1, 2000 and March 31, 2019. All biopsy specimens were examined by a board-certified renal pathologist. The patients were considered to have minimal change disease when the kidney biopsy specimen had no glomerular lesions or only mild focal mesangial prominence (not exceeding 3 or 4 cells per segment) by light microscopy and/or foot process effacement by electron microscopy. Logistic regression and Kaplan-Meier curve analyses were performed, comparing the data of patients who received diuretics or not.The median age was 47 (28-66) years, 52% of patients were women, and the median proteinuria dosage was 8.3 (5.3-11.2) g/d. When minimal change disease was diagnosed, 27% of patients were taking diuretics. Within 30 days after the diagnosis, acute kidney injury occurred in 27% of patients. On multivariable logistic regression analysis, the use of diuretics was significantly associated with a higher risk of acute kidney injury. The use of diuretics was also associated with a longer time to complete remission.Diuretic administration can be associated with an elevated acute kidney injury risk and longer remission time in adult patients with newly diagnosed minimal change disease.

Nephrotic Syndrome

Nephrotic syndrome is one cause of end-stage kidney disease. Because edema is a common presenting feature and hypertension and dyslipidemia are often present in nephrotic syndrome, it is important for the primary care physician to suspect this entity. Common causes in adults include diabetic nephropathy, focal segmental glomerulosclerosis, and membranous nephropathy. In adults, many primary causes are due to an underlying disease. A cause of the nephrotic syndrome should be established with serologic workup and renal consultation. Renal biopsy is necessary in those with an unknown cause to or classify disease. Treatment focuses on symptoms, complications, and the primary cause.

Podocytopathies

Podocytopathies are kidney diseases in which direct or indirect podocyte injury drives proteinuria or nephrotic syndrome. In children and young adults, genetic variants in >50 podocyte-expressed genes, syndromal non-podocyte-specific genes and phenocopies with other underlying genetic abnormalities cause podocytopathies associated with steroid-resistant nephrotic syndrome or severe proteinuria. A variety of genetic variants likely contribute to disease development. Among genes with non-Mendelian inheritance, variants in APOL1 have the largest effect size. In addition to genetic variants, environmental triggers such as immune-related, infection-related, toxic and haemodynamic factors and obesity are also important causes of podocyte injury and frequently combine to cause various degrees of proteinuria in children and adults. Typical manifestations on kidney biopsy are minimal change lesions and focal segmental glomerulosclerosis lesions. Standard treatment for primary podocytopathies manifesting with focal segmental glomerulosclerosis lesions includes glucocorticoids and other immunosuppressive drugs; individuals not responding with a resolution of proteinuria have a poor renal prognosis. Renin-angiotensin system antagonists help to control proteinuria and slow the progression of fibrosis. Symptomatic management may include the use of diuretics, statins, infection prophylaxis and anticoagulation. This Primer discusses a shift in paradigm from patient stratification based on kidney biopsy findings towards personalized management based on clinical, morphological and genetic data as well as pathophysiological understanding.

The efficacy of rituximab in the treatment of refractory nephrotic syndrome: a meta-analysis

OBJECTIVE

The evidence from epidemiological research on whether the efficacy of rituximab in treatment of refractory nephrotic syndrome (NS) is better than other agents is inconsistent. This meta-analysis aimed to assess the efficacy of rituximab in the treatment of NS compared with other immunosuppressive agents.

METHODS

Relevant literatures were identified and evaluated for quality before October 2019 through multiple search strategies on PubMed and EMBASE. Statistical evidence of the symmetry of the funnel plot obtained from Begg's test was indicated by Egger's linear regression and a sensitivity analysis identified heterogeneity. A fixed- or a random-effects model was applied to calculate the pooled SMDs and RRs.

RESULTS

A total of 12 studies, involving 383 patients and 354 controls, were included. Compared with other agents, rituximab significantly improved complete remission both in children and adults [Overall: RR = 1.313, 95% CI = 1.170-1.475, P < 0.001; Adult: RR = 1.359, 95% CI = 1.053-1.753, P = 0.019 Children: RR = 1.354, 95% CI = 1.072-1.709, P < 0.001], and dramatically decreased the relapse rate in children [Overall: RR = 0.349, 95% CI = 0.166-0.732, P < 0.001; Children: RR = 0.286, 95% CI = 0.176-0.463, P < 0.001].

CONCLUSIONS

Rituximab might be a promising treatment for refractory NS. Compared with other agents, rituximab significantly improves the complete remission and decreased the relapse rate. However, to confirm the efficacy of rituximab in the treatment of refractory NS, more high-quality, large sample, and multicenter randomized controlled trials are needed.

Lupus nephritis

Lupus nephritis (LN) is a form of glomerulonephritis that constitutes one of the most severe organ manifestations of the autoimmune disease systemic lupus erythematosus (SLE). Most patients with SLE who develop LN do so within 5 years of an SLE diagnosis and, in many cases, LN is the presenting manifestation resulting in the diagnosis of SLE. Understanding of the genetic and pathogenetic basis of LN has improved substantially over the past few decades. Treatment of LN usually involves immunosuppressive therapy, typically with mycophenolate mofetil or cyclophosphamide and with glucocorticoids, although these treatments are not uniformly effective. Despite increased knowledge of disease pathogenesis and improved treatment options, LN remains a substantial cause of morbidity and death among patients with SLE. Within 10 years of an initial SLE diagnosis, 5-20% of patients with LN develop end-stage kidney disease, and the multiple comorbidities associated with immunosuppressive treatment, including infections, osteoporosis and cardiovascular and reproductive effects, remain a concern. Clearly, early and accurate diagnosis of LN and prompt initiation of therapy are of vital importance to improve outcomes in patients with SLE.

Portal Vein Thrombosis in a 21-Year-Old Man with Membranoproliferative Glomerulonephritis and Nephrotic Syndrome

Membranoproliferative glomerulonephritis, one of the main causes of nephrotic syndrome, is associated with a state of hypercoagulability that leads to increased risk of thrombotic events. Portosystemic collaterals may reopen due to reversal of the flow within the existing veins and be a presenting feature of thrombosis. We describe a patient who presented with large portosystemic collaterals and signs of portal hypertension and was subsequently found to be affected by membranous proliferative glomerulonephritis. Proteinuria and microscopic haematuria in a patient with signs of portal hypertension and no pre-existing liver disease should raise the suspicion of an underlying kidney disease.

Nephrotic Syndrome: Oedema Formation and Its Treatment With Diuretics

Oedema is a defining element of the nephrotic syndrome. Its' management varies considerably between clinicians, with no national or international clinical guidelines, and hence variable outcomes. Oedema may have serious sequelae such as immobility, skin breakdown and local or systemic infection. Treatment of nephrotic oedema is often of limited efficacy, with frequent side-effects and interactions with other pharmacotherapy. Here, we describe the current paradigms of oedema in nephrosis, including insights into emerging mechanisms such as the role of the abnormal activation of the epithelial sodium channel in the collecting duct. We then discuss the physiological basis for traditional and novel therapies for the treatment of nephrotic oedema. Despite being the cardinal symptom of nephrosis, few clinical studies guide clinicians to the rational use of therapy. This is reflected in the scarcity of publications in this field; it is time to undertake new clinical trials to direct clinical practice.

[Pulmonary embolism as a presentation of nephrotic syndrome]

BACKGROUND

Nephrotic syndrome (NS) in adults is defined by proteinuria>3g/24h or 50mg/kg/d, hypoproteinemia<60g/24h and hypoalbuminemia<30g/L. The final diagnosis is guided by the histopathology evidence when a renal biopsy is possible. The consequences of NS are multiple: high blood pressure, undernutrition, infections and a hypercoagulable state.

OBSERVATION

We report the case of a patient presenting with thromboembolic disease, occurring in the absence of other thromboembolic risk factors, which revealed NS with spontaneously favorable evolution.

CONCLUSION

Thromboembolic disease in NS is frequent but underestimated and may remain underdiagnosed. Thorough investigation - including serum protein levels and testing for proteinuria - are essential in thromboembolism, as is excluding cancer or another cause. The treatment of thromboembolic disease in NS is based on anticoagulation for as long as the NS persists. There is no consensus about primary prophylaxis but an albumin level below 20g/L should be considered as a risk factor of thrombosis and prophylactic anticoagulation should be started.

Rituximab shows no effect on remission in patients with refractory nephrotic syndrome: A MOOSE-compliant meta-analysis

To assess the efficacy of rituximab in treatment of refractory nephrotic syndrome (NS) compared with other agents.Studies were searched from Web of Science, PubMed, and CNKI up to April 2016. The standardized mean difference or relative risk or odds ratio and 95% confidence intervals were used to assess the efficacy of rituximab treatment compared with other agents in refractory NS.Totally, 8 studies were included. The present study showed that there was a significant higher relapse-free survival rate in rituximab group than that in the other agents group. Compared with other agents, rituximab did not significantly improve the complete and overall remission rate, serum albumin levels. Rituximab also did not decrease the serum creatinine, urinary protein, and serum cholesterol levels. However, compared with other agents, the adult patients had a higher serum cholesterol levels after treatment with rituximab.Rituximab promised to be a new agent in the treatment of refractory NS; it also could be used as an alternative to conventional immunosuppressive drugs-dependent or drugs-resistant. However, more high-quality, large sample, and multicenter randomized controlled trials are needed to further confirm the efficacy of rituximab in treatment of refractory NS.

Mammary-type myofibroblastoma with the nephrotic syndrome

We describe a 23-year-old white man who presented with anasarca and a new periumbilical mass. He had preserved kidney function and laboratory findings consistent with nephrotic syndrome, including 9.7 g/day albuminuria. Serum serologies were positive for anti-SSa and anti-SSb and low complements but were negative for antinuclear antibody. Pathologic findings of the abdominal mass showed a mammary-type myofibroblastoma. A kidney biopsy revealed a diffuse proliferative and membranous immune-mediated glomerulonephritis with 10% interstitial fibrosis. This is a novel case of mammary-type myofibroblastoma associated with nephrotic syndrome mimicking a proliferative lupus pattern.

Patients with primary membranous nephropathy are at high risk of cardiovascular events

Here we conducted a retrospective study to examine the risk of cardiovascular events (CVEs) relative to that of end-stage renal disease (ESRD) in patients with primary membranous nephropathy, in a discovery cohort of 404 patients. The cumulative incidence of CVEs was estimated in the setting of the competing risk of ESRD with risk factors for CVEs assessed by multivariable survival analysis. The observed cumulative incidences of CVEs were 4.4%, 5.4%, 8.2%, and 8.8% at 1, 2, 3, and 5 years respectively in the primary membranous nephropathy cohort. In the first 2 years after diagnosis, the risk for CVEs was similar to that of ESRD in the entire cohort, but exceeded it among patients with preserved renal function. Accounting for traditional risk factors and renal function, the severity of nephrosis at the time of the event (hazard ratio 2.1, 95% confidence interval 1.1 to 4.3) was a significant independent risk factor of CVEs. The incidence and risk factors of CVEs were affirmed in an external validation cohort of 557 patients with primary membranous nephropathy. Thus early in the course of disease, patients with primary membranous nephropathy have an increased risk of CVEs commensurate to, or exceeding that of ESRD. Hence, reduction of CVEs should be considered as a therapeutic outcome measure and focus of intervention in primary membranous nephropathy.

Acute ischemic stroke associated with nephrotic syndrome: Incidence and significance - Retrospective cohort study

We report 10 cases with arterial ischemic stroke (AIS) with nephrotic syndrome (NS), and clarified its incidence and clinical characteristics. The patients having albumin less than 3.0 g/dl and serum cholesterol greater than 250 mg/dl at the same time were retrospectively screened from 11,161 cases of stroke. Furthermore, the patients of AIS showing heavy proteinuria were selected. The 10 cases were diagnosed as AIS with NS. Its incidence was 0.09% of all kinds of stroke and 0.12% of AIS. Their subtypes were 6 large-artery atherosclerosis, 3 small-vessel occlusion, and 1 cardioembolism. We carried out a retrospective cohort study to assess the association between NS and atherosclerosis progression in AIS patients. Seven AIS patients with NS due to diabetic nephropathy (cases; NS group) were compared with patients with AIS and diabetes mellitus (DM) without NS (control group). Control group subjects were matched in a 2:1 ratio to cases by age, sex, use of medications for DM, and hemoglobin A1c (HbA1c) level. The NS group had high cerebral artery atherosclerosis scores, especially in the anterior circulation. The NS group demonstrated atherosclerosis of the internal carotid and lower extremity arteries, although there were no statistical differences between the two groups. Study subjects had high serum fibrinogen and D-dimer levels, suggesting that AIS patients with NS have a greater degree of hypercoagulability than AIS patients without NS.

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We report 10 cases with arterial ischemic stroke (AIS) with nephrotic syndrome (NS).

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The incidence AIS with NS was clarified.

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By a retrospective cohort study, AIS with NS showed atherosclerosis progression comparing the controls.

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AIS patients with NS have a greater degree of hypercoagulability than AIS patients without NS.

Serological markers of viral, syphilitic and toxoplasmic infection in children and teenagers with nephrotic syndrome: case series from Mato Grosso State, Brazil

Some infections can be the cause of secondary nephrotic syndrome. The aim of this study was to describe the experience of a Renal Disease Reference Clinic from Central Brazil, in which serological markers of some infectious agents are systematically screened in children with nephrotic syndrome. Data were obtained from the assessment of medical files of all children under fifteen years of age, who matched nephrotic syndrome criteria. Subjects were tested for IgG and IgM antibodies against T. gondii and cytomegalovirus; antibodies against Herpes simplex, hepatitis C virus and HIV; and surface antigen (HBsAg) of hepatitis B virus. The VDRL test was also performed. 169 cases were studied. The median age on the first visit was 44 months and 103 (60.9%) patients were male. Anti-CMV IgG and IgM were found in 70.4% and 4.1%, respectively. IgG and IgM against Toxoplasma gondii were present in 32.5% and 5.3%, respectively. Two patients were positive for HBsAg, but none showed markers for HIV, hepatitis C, or Treponema pallidum. IgG and IgM against herpes simplex virus were performed on 54 patients, of which 48.1% and 22.2% were positive. IgM antibodies in some children with clinical signs of recent infection suggest that these diseases may play a role in the genesis of nephrotic syndrome.

Pathophysiology, Evaluation, and Management of Edema in Childhood Nephrotic Syndrome

Generalized edema is a major presenting clinical feature of children with nephrotic syndrome (NS) exemplified by such primary conditions as minimal change disease (MCD). In these children with classical NS and marked proteinuria and hypoalbuminemia, the ensuing tendency to hypovolemia triggers compensatory physiological mechanisms, which enhance renal sodium (Na(+)) and water retention; this is known as the "underfill hypothesis." Edema can also occur in secondary forms of NS and several other glomerulonephritides, in which the degree of proteinuria and hypoalbuminemia, are variable. In contrast to MCD, in these latter conditions, the predominant mechanism of edema formation is "primary" or "pathophysiological," Na(+) and water retention; this is known as the "overfill hypothesis." A major clinical challenge in children with these disorders is to distinguish the predominant mechanism of edema formation, identify other potential contributing factors, and prevent the deleterious effects of diuretic regimens in those with unsuspected reduced effective circulatory volume (i.e., underfill). This article reviews the Starling forces that become altered in NS so as to tip the balance of fluid movement in favor of edema formation. An understanding of these pathomechanisms then serves to formulate a more rational approach to prevention, evaluation, and management of such edema.

[Nephrotic syndrome revealed by pulmonary embolism: about four cases]

Nephrotic syndrom is an association of proteinuria>3g/d or 50mg/kg/d, an hypoalbuminemia<30g/L and a hypoproteinemia<60g/L. Primary etiologies are minimal glomerular injury, focal segmental glomerulosclerosis and non membranous glomerulonephritis. Secondary etiologies are diabetes, high blood pressure and amyloidosis. We present four cases about nephrotic syndrome after thromboembolic disease. In every case, patients show a pulmonary embolism symptomatic of a nephrotic syndrom, whose diagnostic could be delayed up to six months after first pulmonary symptoms. This raised the problem of renal biopsy in these patients who need anticoagulation. In minimal change nephrosis, without hematuria, high blood pressure or renal dysfonction, a corticosteroid therapy test could be done assuming that is corticosensitive minimal glomerular injury. In every case, anticoagulation course must be completed and maintained in case of patent nephrotic syndrom with an albuminemia under 20g/L. In case of pulmonary embolism or deep vein thrombosis, idiopathic-looking, a nephrotic syndrome must be sought-after. The two diagnosis ways are the proteinuria on the urine dipstick and the hypoproteinemia on usual biology. The main mechanism is the coagulation factor leak, side effect of the nephrotic syndrom, notably because of the antithrombin III.

Draining the edema: a new role for aquaretics?

Investigations into edema formation in nephrotic syndrome have mostly focused on the primary role of sodium. While there is controversy about whether sodium retention is an inherent aspect of nephrotic syndrome (overfill hypothesis) or a secondary consequence (underfill hypothesis), the critical role of sodium in driving fluid retention is generally accepted. Consequently, treatment of edema is based on enhancing renal sodium excretion, using saluretics to block tubular reabsorption of sodium. However, there is also evidence of renal water retention: urine in nephrotic patients is typically highly concentrated (unless urinary concentrating ability is impaired by loop diuretics), and vasopressin levels are commonly elevated. Consequently, aquaretics, i.e., drugs that inhibit renal water reabsorption, may constitute effective treatments for nephrotic edema. In fact, these drugs are already approved for the treatment of non-nephrotic edematous states, such as those encountered in congestive heart or liver failure. In this edition of Pediatric Nephrology, two case reports raise the possibility that aquaretics may also be helpful in the treatment of nephrotic edema. These case reports provide no solid evidence for such treatment, and there clearly are serious concerns about inducing critical hypovolemia with potentially catastrophically consequences, such as thrombosis and shock. Yet these concerns similarly apply to saluretics, which clinicians routinely use in the treatment of edema. In addition, the described powerful effect of aquaretics with respect to the resolution of edema, as well as our understanding of the underlying physiology, argue for a more systematic, yet careful assessment of these drugs in the treatment of nephrotic syndrome.

Serum D-dimer concentrations in nephrotic syndrome track with albuminuria, not estimated glomerular filtration rate

BACKGROUND

The nephrotic syndrome is associated with an increased risk of venous and arterial thrombosis. There are little published data on the distribution, interpretation or determinants of serum D-dimer levels in patients with the nephrotic syndrome. We aimed to describe this relationship.

METHODS

This was a cross-sectional study of 100 patients with the nephrotic syndrome. Multivariate linear regression was used to evaluate for independent predictors of elevated D-dimer levels. Patients were observed for a period of 2 years after the baseline measurement of D-dimer level to assess for subsequent clinically evident thrombosis.

RESULTS

On univariate linear regression, D-dimer elevation was associated with age in years β (95% CI) 0.02 (0.016, 0.03), log-transformed urinary protein:creatinine ratio in g/g 0.439 (0.32, 0.558) and inversely with serum albumin in g/l -0.05 (-0.073, -0.035) and estimated glomerular filtration rate (eGFR) in ml/min/1.73 m(2) -0.01 (-0.016, -0.003). On multivariate linear regression, age in years β (95% CI) 0.019 (0.012, 0.026), serum albumin in g/l -0.023 (-0.043, -0.003), and log-transformed urinary protein:creatinine ratio in g/g 0.266 (0.124, 0.408) were independently associated with elevated D-dimer levels.

CONCLUSION

D-dimer levels are commonly raised in the nephrotic syndrome in the absence of clinically evident thrombosis, and are independently associated with age, degree of proteinuria and serum albumin, but not with eGFR. Baseline levels of D-dimer did not predict subsequent episodes of clinically evident thrombosis after 2 years of follow-up.

Factors associated with osteonecrosis in Thai lupus patients: a case control study

OBJECTIVE

To identify associated factors for the development of osteonecrosis of a femoral head (ON) in patients with systemic lupus erythematosus (SLE).

METHODS

We conducted a retrospective nested case-control study from SLE patients who attended the Rheumatology Clinic at Phramongkutklao Hospital from 1992-2008. Cases were defined as SLE patients, who had clinically apparent ON (confirmed by plain radiographs or magnetic resonance imaging). For each case, a control was selected and matched to the case by age and disease duration. The main outcome measure was the odds ratio (OR) of ON among SLE patients. The clinical and laboratory variables thought to be risk factors of ON variables were compared between patients who did and did not develop ON. Significant and clinically relevant variables were then examined by a stepwise logistic regression model.

RESULTS

Of 186 SLE patients, we identified 41 patients who developed ON during the course of follow-up. Twenty patients were available for data analysis. From the univariate analysis, incidence of renal involvement and the use of steroids (recorded as evidenced by maximum and mean daily prednisolone dose) were significantly higher in the ON group than in controls. The use of antimalarials was significantly lower in patients with ON than in controls. No difference in disease activity, lipid profiles or anticardiolipin antibody was found between groups. In the logistic regression, the presence of renal involvement remained as a positive associated factor for ON (OR = 7.80, CI = 1.249-48.748, P = 0.028) and the use of antimalarial drugs was a negative associated factor for ON (OR = 0.09, CI = 0.009-0.961, P = 0.046).

CONCLUSION

The presence of renal involvement was associated with ON and the antimalarial use may have a protective effect for ON in Thai patients with SLE. The findings from this study further support the use of antimalarial drugs in SLE patients.

New role for plasmin in sodium homeostasis

PURPOSE OF REVIEW

Hypertension and edema are clinical manifestations of the extracellular volume expansion generated by abnormal renal sodium handling. Perturbations in epithelial sodium channel (ENaC) activity disrupt volume homeostasis. ENaC activity can be enhanced by proteases that cleave its long extracellular domains. Recent evidence suggests that this mechanism may be involved in individuals with volume overload and proteinuria.

RECENT FINDINGS

Several observations indicate a link between proteinuria and hypertension, with proteinuria preceding and predicting the onset of incident hypertension in some individuals. Recently, enhanced cleavage of ENaC's extracellular loops was identified in kidney tissue of proteinuric mice. Plasmin, a serine protease known for its role in fibrinolysis, has been implicated as an activator of ENaC in proteinuric states as nephrotic urine activates ENaC expressed in a mouse collecting duct cell line, aprotinin-affinity precipitation of nephrotic urine abolishes its ability to activate ENaC, plasmin is a major component within aprotinin-affinity purified nephrotic urine and is absent in nonproteinuric urine, and plasmin activates ENaC by cleaving the extracellular loop of its gamma subunit.

SUMMARY

Enhancement of ENaC activity by proteases represents a likely mechanism for extracellular volume overload relevant to some individuals with proteinuria. Proteases not normally found in the urine can enter the urinary space across damaged glomeruli and activate ENaC. Further understanding of this mechanism may guide targeted therapeutics in individuals with proteinuria, edema, and hypertension.

Final height of adults with childhood-onset steroid-responsive idiopathic nephrotic syndrome

The aim of this study was to evaluate the final stature of adults with childhood-onset steroid-responsive idiopathic nephrotic syndrome (INS) and the influence of disease-related issues on the achievement of their target heights. We analyzed 60 (41 male) patients and/or their records, with a minimum age of 19 years or at a Tanner's pubertal stage 4 for boys or status postmenarche for girls, and normal glomerular filtration rate. Mean age at first and last consultation was 5.3+/-2.4 years and 20.5+/-3.1 years, respectively. Mean follow-up period was 15.10 years. Mean cumulative dose of prednisone was 1254+/-831.40 mg/kg. Mean initial and final height Z scores (HtZ) were, respectively, -0.60+/-1.0 and -0.64+/-0.92 (p=0.72). The final HtZ showed a significant correlation only with the initial HtZ and the target HtZ (THZ). Six patients achieved a final HtZ below -2, which in male patients correlated strongly to the initial HtZ and THZ. A strong correlation was demonstrated between final HtZ, initial HtZ, and THZ. INS-related issues did not prevent the final stature to reach the predicted target height.

Expression profiling of hepatic genes associated with lipid metabolism in nephrotic rats

Hyperlipidemia is one of the major features of nephrotic syndrome (NS). Although many factors have been implicated in the pathogenesis of NS-related dyslipidemia, the underlying mechanisms remain largely uncharacterized. The present study was designed to examine the gene profile associated with lipid metabolism in the livers of nephrotic rats. NS was created in male Sprague-Dawley rats (n = 6) receiving sequential intraperitoneal injections of puromycin aminonucleoside. Analysis by Affymetrix assay, quantitative RT-PCR, and Northern and Western blotting revealed 21 genes associated with cholesterol and fatty acid metabolism. Eight genes involved in cholesterol metabolism, Apo A-I, Acly, Acat, Mpd, Fdps, Ss, Lss, and Nsdhl, were significantly upregulated under NS. Four genes involved in fatty acid biosynthesis, Acc, FAS, ELOVL 2, and ELOVL6, and three critical for triglyceride biosynthesis, Gpam, Agpat 3, and Dgat 1, were significantly upregulated, whereas two genes involved in fatty acid oxidation, Dci and MCAD, were downregulated. Expression of several genes in sterol-regulatory element-binding protein (SREBP)-1 activation was also aberrantly altered in nephrotic livers. The expression and transcriptional activity of SREBP-1 but not SREBP-2 were increased in nephrotic rats as assessed by real-time PCR, immunoblotting, and gel shift assays. The upregulation of hepatic genes involved in cholesterol biosynthesis may play an important role in the pathogenesis of hypercholesterolemia, whereas upregulation of genes participating in hepatic fatty acid and triglyceride biosynthesis and downregulation of genes involved in hepatic fatty acid oxidation may contribute to hypertriglyceridemia in nephrotic rats. Activation of SREBP-1 transcription factor may represent an underlying molecular mechanism of hyperlipidemia in NS.

Adult minimal-change disease: clinical characteristics, treatment, and outcomes

Minimal-change disease (MCD) counts for 10 to 15% of cases of primary nephrotic syndrome in adults. Few series have examined this disease in adults. A retrospective review was performed of 95 adults who had MCD and were seen at a single referral center. Examined were presenting features, response to daily versus alternate-day steroids, response to second-line agents, relapse patterns, complications of the disease and therapy, presence of acute renal failure (ARF), and outcome data. Sixty-five patients received daily and 23 received alternate-day steroids initially. There were no differences in remissions, time to remission, relapse rate, or time to relapse between daily- and alternate-day-treated patients. More than one quarter of patients were steroid resistant. At least one relapse occurred in 73% of patients; 28% were frequently relapsing. A significant proportion of frequently relapsing patients became steroid dependent. Second-line agents were used for steroid dependence, steroid resistance, or frequent relapses. No single agent proved superior. There were more remissions with second-line agents in steroid-dependent patients compared with steroid-resistant patients, and remissions were more likely to be complete in steroid-dependent patients. ARF occurred in 24 patients; they tended to be older and hypertensive with lower serum albumin and more proteinuria than those without ARF. At follow up, patients with an episode of ARF had higher serum creatinine than those without ARF. Four patients progressed to ESRD. These patients were less likely to have responded to steroids and more likely to have FSGS on repeat renal biopsy. In this referral MCD population, response to daily and alternate-day steroids is similar. Second-line agents give greater response in patients who are steroid dependent. ARF occurs in a significant number of adult MCD patients and may leave residual renal dysfunction. Few patients progress to ESRD.

La fuite urinaire d'érythropoïétine : une cause méconnue d'anémie au cours des syndromes néphrotiques

INTRODUCTION

Nephrotic syndrome (NS) is characterized by an excessive urinary protein excretion.

CASE RECORD

A woman, followed-up for NS, present progressive anemia, with no simple explanation. Plasma EPO is low with significant urinary EPO excretion. Treatment with EPO corrects hemoglobin level.

CONCLUSION

EPO deficiency due to excessive urinary excretion is an underestimated cause of anemia during NS.

Proteinuria and hemoglobin levels in patients with primary glomerular disease

BACKGROUND

Anemia in association with nephrotic syndrome has been described in small patient series and case reports. Whether nephrotic patients develop anemia has not been formally investigated.

METHODS

We undertook a retrospective cross-sectional study of patients with biopsy-proven primary glomerular disease, various degrees of proteinuria, and creatinine levels less than 2 mg/dL (< 177 micromol/L). In addition to proteinuria, values for hemoglobin (Hb), age, body mass index (BMI), serum albumin and protein, and estimated glomerular filtration rate (eGFR) were derived from patient charts.

RESULTS

We studied 297 patients, 187 men and 110 women, aged between 16 and 81 years. Univariate analysis showed no correlation between Hb level and proteinuria in either sex. Stratification of women and men into quartiles according to proteinuria showed no differences in Hb levels among the 4 groups. Three of 52 non-nephrotic women (6%) were anemic (Hb < 12 g/dL [< 120 g/L]) compared with 11 of 58 nephrotic women (19%; P = 0.047). Multiple regression analysis of all patients showed Hb level to have a correlation with sex (P < 0.001), BMI (P < 0.001), and eGFR (P = 0.005); negative correlation with age (P = 0.028); and borderline negative correlation with proteinuria (P = 0.054). In women, BMI showed a positive correlation with Hb level (P = 0.030). Proteinuria did not reach statistical significance (P = 0.093). In men, BMI (P = 0.001) and eGFR (P = 0.013) were associated positively and age (P = 0.031) was associated negatively with Hb level.

CONCLUSION

These results indicate that nephrotic syndrome is not associated with anemia in men, but with a tendency to decrease Hb levels in women.

Treatment of focal segmental glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS) is not a disease, but a lesion affecting the podocyte. Secondary FSGS may be due to a host of various factors, and patients are rarely nephrotic, requiring symptomatic treatment only. The best prognostic feature of nephrotic FSGS is its response to corticosteroids. Some forms are most likely of immunological origin, relapse in a renal transplant and justify immunosuppressive treatment. In a growing number of cases, genetic profiling of molecules that contribute to the podocyte slit diaphragm permselectivity to albumin has identified defects that do not represent indications for immunosuppression. In the other forms, corticosteroids and cyclosporin A (CsA) remain the mainstay of treatment, with better efficacy when CsA is associated with steroids. The renal tolerability of CsA is reasonably good when the dosage is low. CsA dependency is not constant. Alkylating agents are reluctantly indicated in steroid-sensitive forms, which are rare. They are mostly ineffective in steroid-resistant forms. Tacrolimus seems a promising therapy with low toxicity, but it is usual for dependency on the drug to occur. Sirolimus seems to be ineffective. Azathioprine is not considered indicated, despite rare reports with favourable results, which would deserve further controlled trials. Recent publications indicate that mycophenolate mofetil might usefully find a place in the treatment. Plasmapheresis is of no avail outside the special case of relapse in a transplanted kidney. Immunoabsorption of the elusive substance that causes the nephrotic syndrome and its relapse on a transplant has not led to practical treatment options.