Nephrotic syndrome-induced thromboembolism in adults

Nephrotic syndrome (NS) is a well-defined syndrome characterized by the presence of nephrotic range of proteinuria, hypoalbuminemia, and hyperlipidemia. Although venous thromboembolism (VTE) is a well-reported complication associated with NS, the incidence, prevalence, risk factors, treatment options, and preventative strategies are not well-established. Thromboembolic phenomena in nephrotic patients are postulated to be a result of the urinary loss of antithrombotic factors by affected kidneys and increased production of prothrombotic factors by the liver. Most cases of VTE associated with NS reported in the literature have a known diagnosis of NS. We report a case of a young female presenting with dyspnea and a pulmonary embolism. She was found to have NS and right renal vein thrombosis. We review the available literature to highlight the best approach for clinicians treating VTE in patients with NS.

Related papers:

title: Primary Nephrotic Syndrome in Adults as a Risk Factor for Pulmonary Embolism: An Up-to-Date Review of the Literature
abstract: Patients with nephrotic syndrome are at an increased risk for thrombotic events; deep venous thrombosis, renal vein thrombosis, and pulmonary embolism are quite common in patients with nephrotic syndrome. It is important to note that nephrotic syndrome secondary to membranous nephropathy may impose a greater thrombotic risk for unclear reasons. Increased platelet activation, enhanced red blood cell aggregation, and an imbalance between procoagulant and anticoagulant factors are thought to underlie the excessive thrombotic risk in patients with nephrotic syndrome. The current scientific literature suggests that patients with low serum albumin levels and membranous nephropathy may benefit from primary prophylactic anticoagulation. A thorough approach which includes accounting for all additional thrombotic risk factors is, therefore, essential. Patient counseling regarding the pros and cons of anticoagulation is of paramount importance. Future prospective randomized studies should address the question regarding the utility of primary thromboprophylaxis in patients with nephrotic syndrome.

title: Pulmonary embolism and renal vein thrombosis in patients with nephrotic syndrome: prospective evaluation of prevalence and risk factors with CT.
abstract: To prospectively determine the prevalence of pulmonary embolism ( PE pulmonary embolism ) and renal vein thrombosis ( RVT renal vein thrombosis ) with computed tomography (CT) and to identify markers predictive of PE pulmonary embolism and/or RVT renal vein thrombosis in a large consecutive cohort of patients with nephrotic syndrome.



This study was approved by the local institutional review board, and all patients or their guardians provided written informed consent. Consecutive patients with nephrotic syndrome (24-hour urine protein > 3.5 g) underwent combined CT pulmonary angiography for PE pulmonary embolism and renal CT venography for RVT renal vein thrombosis . Prevalence of PE pulmonary embolism and/or RVT renal vein thrombosis was estimated for different ages, sexes, and histopathologic types of nephrotic syndrome. Multivariate analysis was used to determine independent predictors for PE pulmonary embolism and/or RVT renal vein thrombosis in patients with nephrotic syndrome.



There were 512 patients in the study cohort (331 male patients, 181 female patients; mean age, 37 years ± 17 [standard deviation]; range, 9-81 years), including 80 children. One hundred eighty (35%) of 512 patients had PE pulmonary embolism and/or RVT renal vein thrombosis , with PE pulmonary embolism the more common condition (85% [153 of 180]). PE pulmonary embolism was associated with RVT renal vein thrombosis in 85 (56%) of 153 patients and was isolated in 68 patients (44%). Most patients with PE pulmonary embolism (84% [128 of 153]) were asymptomatic. One hundred twelve (22%) of 505 patients had RVT renal vein thrombosis . PE pulmonary embolism and/or RVT renal vein thrombosis was found in 15 (19%) of 80 children with nephrotic syndrome, while 165 (38%) of 432 adult patients with nephrotic syndrome had PE pulmonary embolism and/or RVT renal vein thrombosis (P = .001). Membranous nephropathy was the most common histopathologic type associated with PE pulmonary embolism and/or RVT renal vein thrombosis (48% [88 of 183]). Membranous nephropathy, age greater than 60 years, high hemoglobin level, long prothrombin time, and high creatinine level were independent predictors of PE pulmonary embolism and/or RVT renal vein thrombosis (P < .05 for all).



PE pulmonary embolism and RVT renal vein thrombosis are common in patients with nephrotic syndrome. PE pulmonary embolism is more common than RVT renal vein thrombosis , is most often asymptomatic, and is most frequently found in patients with membranous nephropathy. A high index of suspicion and a low threshold for diagnostic work-up is warranted in these patients.

title: Retrospective analysis of a novel regimen for the prevention of venous thromboembolism in nephrotic syndrome.
abstract: Venous thromboembolism (VTE) occurs in 7%-40% of nephrotic patients. The risk of VTE depends on the severity and underlying cause of nephrotic syndrome. This study investigated the use of low-dose prophylactic anticoagulation to prevent VTE in patients with nephrotic syndrome caused by primary glomerulonephritis.



Since 2006, all patients presenting with nephrotic syndrome to Imperial College Kidney and Transplant Centre have been considered for treatment with a novel anticoagulation prophylaxis regimen. All cases of nephrotic syndrome secondary to primary membranous nephropathy, minimal-change disease, and FSGS over a 5-year period were retrospectively reviewed. Patients with serum albumin<2.0 g/dl received prophylactic-dose low-molecular-weight heparin or low-dose warfarin; patients with albumin levels of 2.0-3.0 g/dl received aspirin, 75 mg once daily. All thrombotic events and bleeding complications were recorded.



A total of 143 patients received the prophylactic anticoagulation regimen. Median follow-up was 154 weeks (range, 30-298 weeks). The cohort had features associated with a high risk of developing VTE; 40% of the cohort had an underlying diagnosis of membranous nephropathy, and the initial median serum albumin was 1.5 g/dl (range, 0.5-2.9 g/dl). No VTE occurred in patients established on prophylaxis for at least 1 week. VTE was diagnosed in 2 of 143 patients (1.39%) within the first week after presentation and starting prophylaxis. In both cases, it is unclear whether the thrombus had developed before or after the start of prophylaxis. One of 143 (0.69%) patients receiving prophylaxis was admitted urgently with gastrointestinal hemorrhage. Two of 143 patients (1.40%) had elective blood transfusions and procedures to manage occult gastrointestinal bleeding. No other bleeding events occurred in patients receiving prophylaxis.



This regimen of prophylactic antiplatelet or anticoagulant therapy appears effective in preventing VTE in nephrotic syndrome, with relatively few hemorrhagic complications.

title: Thromboembolic complications in nephrotic syndrome. Coagulation abnormalities, renal vein thrombosis, and other conditions.
abstract: In patients with nephrotic syndrome, the presence of a hypercoagulable state is thought to give rise to a high incidence of thromboembolic phenomena. Renal vein thrombosis is a common complication in nephrotic patients, mainly in those with membranous nephropathy, and many other types of thromboembolic complications also occur. The mortality rate in nephrotic patients with thromboembolic complications may be significantly increased, with pulmonary emboli likely being the most common cause of death.

title: Venous thromboembolism in patients hospitalized with nephrotic syndrome.
abstract: Whether pulmonary embolism in patients with the nephrotic syndrome is caused by deep venous thrombosis or renal vein thrombosis is controversial. To determine which is the likely cause of pulmonary embolism in patients with the nephrotic syndrome, we investigated data from the National Hospital Discharge Survey.



The number of patients discharged from nonfederal short-stay hospitals in the United States with a diagnostic code of nephrotic syndrome, deep venous thrombosis, renal vein thrombosis, and pulmonary embolism was obtained using ICD-9-M (International Classification of Diseases, Ninth Revision, Clinical Modification) codes.



From 1979 to 2005, 925,000 patients were discharged from hospitals with the nephrotic syndrome and 898,253,000 patients did not have the nephrotic syndrome. With the nephrotic syndrome, 5000 (0.5%) had pulmonary embolism, 14,000 (1.5%) had deep venous thrombosis, and fewer than 5000 had renal vein thrombosis. The relative risk of pulmonary embolism comparing patients with the nephrotic syndrome to those who did not have it was 1.39, and the relative risk of deep venous thrombosis was 1.72. Among patients aged 18-39 years, the relative risk of deep venous thrombosis was 6.81. From 1991-2005, after venous ultrasound was generally available, the relative risk of deep venous thrombosis (all ages) was 1.77.



The nephrotic syndrome is a risk factor for venous thromboembolism. This is strikingly apparent in young adults. Renal vein thrombosis was uncommon. Therefore, pulmonary embolism, if it occurs, is likely to be due to deep venous thrombosis and not renal vein thrombosis.

title: Thromboembolic complications in childhood nephrotic syndrome: a clinical profile
abstract: BackgroundThromboembolism is a rare life-threatening complication of childhood nephrotic syndrome.MethodsWe present the clinical profile and outcome of 34 children with 35 events of thromboembolic complications with nephrotic syndrome.ResultsCerebral venous thrombosis (CVT) was the commonest complication seen in 11 (31.4 %) children followed by pulmonary thromboembolism and deep venous thrombosis in 9 (25.7 %) and 6 (16.6 %) children, respectively. Arterial thrombosis resulting in central nervous system infarcts was observed in 7 (20 %) children and 2 children had thrombosis of the peripheral arteries. Episodes were equal in steroid-resistant nephrotic syndrome and steroid-dependent nephrotic syndrome groups. Most of the thromboembolic complications occurred with relapse but 11.4 % of children developed intracranial thrombosis during remission. The most sensitive symptom of CVT was persistent headache while unexplained respiratory distress and hypoxemia pointed towards pulmonary thromboembolism. Hypoalbuminemia was seen in 82.8 % of children, while concurrent infection was seen in 31.4 %. Coexistence of genetic prothrombotic condition was identified and merits evaluation. Early heparin therapy followed by oral anticoagulants resulted in complete recovery in 91.1 % of children. Death occurred in 3 (8.5 %) children and autopsy revealed pulmonary thromboembolism in 2 children.ConclusionVenous and arterial thrombotic complications can occur in children with nephrotic syndrome. A high index of suspicion is required as the clinical features may be subtle. Neuroimaging and angiographic techniques help in confirming diagnosis. Early aggressive heparin therapy followed by oral anticoagulants is necessary for a favorable outcome.

title: Thromboembolic complications in membranous nephropathy patients with nephrotic syndrome-a prospective study.
abstract: Venous thromboembolism (VTE) is one of the most serious complications in membranous nephropathy (MN). We investigate the incidence of VTE in MN patients with nephrotic syndrome (NS).



A total of 100 MN patients with NS were enrolled into this prospective study. The diagnosis of VTE was based on contrast-enhanced dual source computed tomography angiography.



Venous thromboembolism was demonstrated in 36 patients (36%). 33 patients (33%) had renal vein thrombosis (RVT), 17 patients (17%) had pulmonary embolism (PE). Flank pain was noted in 5 patients and gross hematuria in 2 patients with RVT. Dyspnea and chest pain were present in 9 patients with PE. The positive predictive value for D-dimer level was 69.4%, negative predictive value for D-dimer level was 96.1% in patients with MN. Of all the risk factors presented, D-dimer level, proteinuria, the ratio of proteinuria to serum albumin were independent risk factors for the development of VTE (P<0.05), but the plasma level of antithrombin Ш was not correlated with VTE in this study. In follow up, venous thrombosis disappeared after anticoagulant treatment with low-molecular-weight heparins in 28 patients.



Venous thromboembolism was confirmed in 36% of MN patients with NS. Renal vein thrombosis and pulmonary embolism are common and usually asymptomatic. Computed tomography angiography can be used effectively to examine suspected patients. Measurement of D-dimer is helpful in VTE diagnosis. It is important that clinicians are aware that VTE should be considered as a common complication in MN patients with NS.

title: High Absolute Risks and Predictors of Venous and Arterial Thromboembolic Events in Patients With Nephrotic Syndrome: Results From a Large Retrospective Cohort Study
abstract: No data are available on the absolute risk of either venous thromboembolism (VTE) or arterial thromboembolism (ATE) in patients with nephrotic syndrome. Reported risks are based on multiple case reports and small studies with mostly short-term follow-up. We assessed the absolute risk of VTE and ATE in a large, single-center, retrospective cohort study and attempted to identify predictive factors in these patients.  A total of 298 consecutive patients with nephrotic syndrome (59% men; mean age, 42±18 years) were enrolled. Mean follow-up was 10±9 years. Nephrotic syndrome was defined by proteinuria ≥3.5 g/d, and patients were classified according to underlying histological lesions accounting for nephrotic syndrome. Objectively verified symptomatic thromboembolic events were the primary study outcome. Annual incidences of VTE and ATE were 1.02% (95% confidence interval, 0.68 to 1.46) and 1.48% (95% confidence interval, 1.07 to 1.99), respectively. Over the first 6 months of follow-up, these rates were 9.85% and 5.52%, respectively. Proteinuria and serum albumin levels tended to be related to VTE; however, only the predictive value of the ratio of proteinuria to serum albumin was significant (hazard ratio, 5.6; 95% confidence interval, 1.2 to 26.2; P=0.03). In contrast, neither the degree of proteinuria nor serum albumin levels were related to ATE. Sex, age, hypertension, diabetes, smoking, prior ATE, and estimated glomerular filtration rate predicted ATE (P≤0.02).  This study verifies high absolute risks of symptomatic VTE and ATE that were remarkably elevated within the first 6 months. Whereas the ratio of proteinuria to serum albumin predicted VTE, estimated glomerular filtration rate and multiple classic risk factors for atherosclerosis were predictors of ATE.

title: Histological diagnosis and risk of renal vein thrombosis, and other thrombotic complications in primitive nephrotic syndrome.
abstract: The risk of thromboembolic events is increased in patients with nephrotic syndrome (NS) as compared with other medical conditions and is a severe complication associated with significant morbidity and mortality. We aimed to assess the risk of renal vein thrombosis, and other venous thromboembolic events (VTE) in a large cohort of patients with NS and to identify the disease-specific risk for VTE.



We performed a prospective observational study including consecutive adult patients with primitive NS admitted to our department. Clinical and biological data were obtained every six months during follow-up. Occurrence of VTE confirmed by imaging techniques was the primary study outcome.



We enrolled 191 patients (47±15 years, 53% men) with a median follow-up of 24 [IQR:12,36] months. During follow-up, 23 VTE occurred, of which 65.2% in the first six months. The disease-specific risk of VTE during the follow-up period was different across the histological groups, with the lowest risk in minimal change disease and IgA nephropathy and the highest in membranous nephropathy and membranoproliferative glomerulonephritis patients. In the subgroup of membranous, the severity of the subepithelial electron dense deposits did not correlate with the risk for VTE (p=0.5).



In this prospective study, the risk of VTE was higher in the first six months of follow-up in NS patients. The histological pattern seems to influence the risk of VTE in this setting.

title: Venous thromboembolism in patients with membranous nephropathy.
abstract: The aims of this study were to determine the frequency of venous thromboembolic events in a large cohort of patients with idiopathic membranous nephropathy and to identify predisposing risk factors.



We studied patients with biopsy-proven membranous nephropathy from the Glomerular Disease Collaborative Network (n=412) and the Toronto Glomerulonephritis Registry (n=486) inception cohorts. The cohorts were pooled after establishing similar baseline characteristics (total n=898). Clinically apparent and radiologically confirmed venous thromboembolic events were identified. Potential risk factors were evaluated using multivariable logistic regression models.



Sixty-five (7.2%) subjects had at least one venous thromboembolic event, and this rate did not differ significantly between registries. Most venous thromboembolic events occurred within 2 years of first clinical assessment (median time to VTE = 3.8 months). After adjusting for age, sex, proteinuria, and immunosuppressive therapy, hypoalbuminemia at diagnosis was the only independent predictor of a venous thromboembolic event. Each 1.0 g/dl reduction in serum albumin was associated with a 2.13-fold increased risk of VTE. An albumin level <2.8 g/dl was the threshold below which risk for a venous thromboembolic event was greatest.



We conclude that clinically apparent venous thromboembolic events occur in about 7% of patients with membranous nephropathy. Hypoalbuminemia, particularly <2.8 g/dl, is the most significant independent predictor of venous thrombotic risk.

title: Proteinuria and hypoalbuminemia are risk factors for thromboembolic events in patients with idiopathic membranous nephropathy: an observational study
abstract: BackgroundPatients with nephrotic syndrome are at an increased risk of thromboembolic events (TEs). However, this association has not been thoroughly investigated in adult patients with idiopathic membranous nephropathy (IMN).MethodsA retrospective analysis of all 101 consecutive adult patients with MN diagnosed at our centre during 1995 to 2008 was performed. Pertinent data including thromboembolic events and the risk factors for TEs were recorded.ResultsThe cohort was followed for 7.2 ± 3 years. Out of 78 patients with IMN, 15 (19.2%) had at least one TE. No TEs occurred six months after diagnosis. The incidence of TEs in the first 6 months of diagnosis was 7.69% (95%CI, 2.5-17.0) and all patients except one had venous TEs. At the time of diagnosis of MN, the patients with TEs had lower serum albumin (1.9 ± 0.5 vs. 2.4 ± 0.4 g/dl, TE vs. no TE; p < 0.01) and greater serum cholesterol (414 ± 124 vs. 317 ± 108 mg/dl, TE vs. no TE; p = 0.01) and 24-h proteinuria (10.7 ± 3 vs. 7.1 ± 4 g, TE vs. no TE; p < 0.01). Multivariate logistic regression adjusted for age, sex, cholesterol and creatinine revealed, an odds ratio of 0.8 (95% CI 0.7 – 0.96; p = 0.01) for every one g/dl increase in baseline serum albumin and, an odds ratio of 1.3 (95% CI 1.05-1.58; p = 0.01) for one gram increase in 24-h proteinuria, for TEs.ConclusionsOur study finding confirms IMN as a prothrombotic state particularly in the first six months of diagnosis. Proteinuria, in addition to hypoalbuminemia, is a risk factor for TEs. These results have important implications for clinical care of patients with IMN, particularly with regards to initiation and duration of prophylactic anticoagulation.

title: Bilateral renal vein thrombosis and pulmonary embolism secondary to membranous glomerulonephritis treated with percutaneous catheter thrombectomy and localized thrombolytic therapy
abstract: Renal vein thrombosis (RVT) is a rare event but is prevalent in patients with nephrotic syndrome. Bilateral RVT is even rarer. The literature is relatively sparse in terms of the management of RVT because of its rarity and consists of a few case reports and case series. We present a case with bilateral RVT complicated by a pulmonary embolism in a patient with membranous glomerulonephritis (MGN). A 19-year-old female presented with acute flank pain and worsening renal function after a couple of weeks in hospital while being treated with diuretics for anasarca secondary to MGN. Venography was used for diagnosis. The patient underwent percutaneous catheter thrombectomy and localized thrombolysis achieving resolution of pain and improvement of renal function. The patient was then anticoagulated for life with warfarin.

title: Personalized prophylactic anticoagulation decision analysis in patients with membranous nephropathy.
abstract: Primary membranous nephropathy is associated with increased risk of venous thromboembolic events, which are inversely correlated with serum albumin levels. To evaluate the potential benefit of prophylactic anticoagulation (venous thromboembolic events prevented) relative to the risk (major bleeds), we constructed a Markov decision model. The venous thromboembolic event risk according to serum albumin was obtained from an inception cohort of 898 patients with primary membranous nephropathy. Risk estimates of hemorrhage were obtained from a systematic literature review. Benefit-to-risk ratios were predicted according to bleeding risk and serum albumin. This ratio increased with worsening hypoalbuminemia from 4.5:1 for an albumin under 3 g/dl to 13.1:1 for an albumin under 2 g/dl in patients at low bleeding risk. Patients at intermediate bleeding risk with an albumin under 2 g/dl have a moderately favorable benefit-to-risk ratio (under 5:1). Patients at high bleeding risk are unlikely to benefit from prophylactic anticoagulation regardless of albuminemia. Probabilistic sensitivity analysis, to account for uncertainty in risk estimates, confirmed these trends. From these data, we constructed a tool to estimate the likelihood of benefit based on an individual's bleeding risk profile, serum albumin level, and acceptable benefit-to-risk ratio (www.gntools.com). This tool provides an approach to the decision of prophylactic anticoagulation personalized to the individual's needs and adaptable to dynamic changes in health status and risk profile.