Warfarin-related nephropathy in a patient with mild IgA nephropathy on dabigatran and aspirin

Dabigatran-related Nephropathy Complicated by Tubulointerstitial Nephritis in a Patient with a Normal Renal Function and Undiagnosed IgA Nephropathy

A 69-year-old woman was referred to our hospital because of an acute kidney injury with macroscopic hematuria. She had been taking dabigatran for atrial flutter for six years. Based on the typical histological findings of her kidney biopsy and her history of dabigatran use with prolonged activated partial thromboplastin time, she was diagnosed with dabigatran-related nephropathy complicated by tubulointerstitial nephritis with IgA nephropathy. After prednisolone therapy, the renal function improved. Direct-acting oral anticoagulants, including dabigatran, may cause anticoagulant-related nephropathy similar to warfarin, even in patients with a normal renal function. Tubulointerstitial nephritis may coexist with dabigatran-related nephropathy, and prednisolone therapy should be considered in such cases. IgA nephropathy has been reported as a background disease, and caution should be exercised when encountering it.

The Crosstalk between Nephropathy and Coagulation Disorder: Pathogenesis, Treatment, and Dilemmas

ABSTRACT

The interaction between the kidney and the coagulation system greatly affects each other because of the abundant vessel distribution and blood perfusion in the kidney. Clinically, the risks of complicated thrombosis and bleeding have become important concerns in the treatment of nephropathies, especially nephrotic syndrome, CKD, ESKD, and patients with nephropathy undergoing RRTs. Adverse effects of anticoagulant or procoagulant therapies in patients with nephropathy, especially anticoagulation-related nephropathy, heparin-induced thrombocytopenia, and bleeding, seriously worsen the prognosis of patients, which have become challenges for clinicians. Over the decades, the interaction between the kidney and the coagulation system has been widely studied. However, the effects of the kidney on the coagulation system have not been systematically investigated. Although some coagulation-related proteins and signaling pathways have been shown to improve coagulation abnormalities while avoiding additional kidney damage in certain kidney diseases, their potential as anticoagulation targets in nephropathy requires further investigation. Here, we review the progression of research on the crosstalk between the coagulation system and kidney diseases and systematically analyze the significance and shortcomings of previous studies to provide new sight into future research. In addition, we highlight the status of clinical treatment for coagulation disorder and nephropathy caused by each other, indicating guidance for the formulation of therapeutic strategies or drug development.

Anticoagulant-related nephropathy induced by direct-acting oral anticoagulants: Clinical characteristics, treatments and outcomes

INTRODUCTION

There is a scarcity of data on anticoagulation-related nephropathy (ARN) caused by direct-acting oral anticoagulants (DOACs) in recent years.

MATERIALS AND METHODS

We collected literatures on DOACs-induced ARN to October 1, 2022, without language restrictions for retrospective analysis.

RESULTS

Twenty events were included with a median onset time of 28 days among which fourteen were caused by dabigatran. Patients accompanied by chronic kidney disease (85 %) seemed more easily to have an ARN. Clinical symptoms associated with ARN were mostly presented as hematuria and acute decline of renal function (100 %), then abnormal coagulation function (75 %) but only one with an INR over 3. Renal biopsies were performed in 14 patients, with thirteen showing occlusive intratubular red blood cell casts and ten showing acute tubular injury of varying intensity or even tubular necrosis. Extensive changes in interstitial compartment like hemorrhage, fibrosis or inflammation were also presented in eight biopsies. IgA nephropathy as a latent or undiagnosed disease was demonstrated in eight biopsies. Treatments of ARN were mainly supportive with all patients discontinuing DOACs and 35 % initiating dialysis for acute deterioration of renal function. Steroids were used in 9 patients with a severe ARN verified by biopsy. 60 % of patients did not recover baseline renal function and some even deteriorated.

CONCLUSIONS

In conclusion, DOACs-induced ARN is a rare but serious adverse reaction. A prompt diagnosis of ARN and supportive treatments are necessary for patients receiving DOACs concurrent with an acute renal injury.

IgA nephropathy is the most common underlying disease in patients with anticoagulant-related nephropathy

Introduction

Anticoagulant-related nephropathy (ARN) is a relatively novel recognized entity characterized by hematuria-associated acute kidney injury (AKI) in the context of overanticoagulation. Preexisting or underlying kidney disease seems to be a predisposing factor; however, few studies have described histologic findings in patients with ARN. We aimed to evaluate underlying kidney pathology in patients on oral anticoagulation who presented an episode of AKI with hematuria in whom a kidney biopsy was performed.

Methods

Retrospective observational multicenter case study in patients treated with oral anticoagulants who developed macroscopic or intense hematuria followed by AKI. Only patients with available kidney biopsy specimens were included. Histologic findings and clinical data throughout follow-up were analyzed.

Results

A total of 26 patients were included with a median age of 75 years (62–80) and a follow-up period of 10.1 months. Of the patients, 80% were male, and most cases (92%) were on anticoagulation with vitamin K antagonists (VKAs). At admission, median serum creatinine (SCr) level was 4.2 mg/dl (2.8–8.2), median international normalized ratio (INR) 2.4 (1.5–3.4), and 11 patients (42%) required acute dialysis during hospitalization. Kidney biopsy results revealed that all patients except 1 had an underlying nephropathy: IgA nephropathy (IgAN) in 19, probable IgAN in 1, diabetic nephropathy in 3, nephrosclerosis in 1, and idiopathic nodular glomerulosclerosis in 1. At 12 weeks after discharge, only 6 subjects (24%) attained complete kidney recovery whereas 7 (28%) remained on chronic dialysis.

Conclusion

IgAN was the most common underlying kidney disease in our biopsy-proven series of ARN, in which a significant percentage of patients did not achieve kidney function recovery.

Oral anticoagulation in chronic kidney disease with atrial fibrillation

Chronic kidney disease (CKD) and atrial fibrillation (AF) frequently coexist, amplifying the risk of cardiovascular events and mortality. In patients with CKD stage 3 and non-valvular AF, direct oral anticoagulants (DOACs) have shown, compared to vitamin K antagonists (VKA), equal or greater efficacy in the prevention of stroke and systemic embolism, and greater safety. There are no randomizedtrials of the efficacy and safety of DOACs and VKA in advanced CKD. On the other hand, observational studies suggest that DOACs, compared to warfarin, are associated with a lower risk of acute kidney damage and generation/progression of CKD. This paper reviews the epidemiological and pathophysiological aspects of the CKD and AF association, the evidence of the efficacy and safety of warfarin and ACODs in various stages of CKD with AF as well as the comparison between warfarin and ACODs in efficacy and anticoagulant safety, and in its renal effects.

Management of Anticoagulant-Related Nephropathy: A Single Center Experience

BACKGROUND

Anticoagulant-related nephropathy (ARN) is a form of acute kidney injury that mainly occurs in patients with previously unrecognized glomerular disease in addition to excessive anticoagulation. Since a renal biopsy is not performed in most cases, the diagnosis is often presumptive.

METHODS

Here, we present the characteristics of a national Slovenian patient cohort with histologically verified ARN, from the first case in 2014 to December 2020, and a review of the current literature (Pubmed database).

RESULTS

In Slovenia, ARN has been detected in 13 patients, seven of whom were treated with coumarins, and others with direct oral anticoagulants. In seven patients, ARN appeared after excessive anticoagulation. As many as 11 patients had underlying IgA nephropathy. Similar to the global data presented here, the pathohistological impairment associated with pre-existing glomerulopathy was mild and disproportionate to the degree of functional renal impairment. The majority of our patients with ARN experienced severe deterioration of renal function associated with histological signs of accompanying acute tubular injury, interstitial edema, and occlusive red blood cell casts. These patients were treated with corticosteroids, which (in addition to supportive treatment and discontinuation of the anticoagulant drug) led to a further improvement in renal function.

CONCLUSIONS

Anticoagulant therapy combined with a pre-existing glomerular injury may lead to ARN. In addition to discontinuation of the anticoagulant and supportive care, corticosteroids, which are currently listed in only a few cases in the world literature, may have a positive influence on the course of treatment. However, the benefits of steroid treatment must be weighed against the risk of complications, especially life-threatening infections.

Anticoagulation-related nephropathy for the internist: a concise review

Anticoagulation-related nephropathy (ARN) is a clinical entity that has significant morbidity and mortality consequences/burden but has not been well described. Consequently, ARN has been underdiagnosed and sub-optimally managed. ARN has been reported with warfarin use especially in the setting of supratherapeutic international normalized ratio (INR) but the association is far less established with the use of direct-acting oral anticoagulants (DOAC). Accelerated progression to CKD and ultimately ESRD has been reported in patients with ARN. With the expanding indications for DOAC use, there is growing concern about ARN in the setting of DOAC use and its attendant clinical and socioeconomic burden. In this review, we highlight precautionary measures to aid prompt diagnosis of ARN and suggest possible therapeutic strategies.

The Impairment in Kidney Function in the Oral Anticoagulation Era. A Pathophysiological Insight

The need for anticoagulation in patients with atrial fibrillation (AF) is fundamental to prevent thromboembolic events. Direct oral anticoagulants (DOACs) recently demonstrated to be superior, or at least equal, to Warfarin in reducing the risk for stroke/systemic embolism and preventing major bleeding and intracranial hemorrhages. The AF population often suffers from chronic kidney disease (CKD). Indeed, the relationship between AF and renal function is bidirectional: AF can trigger kidney failure, while kidney impairment can promote alterations able to enhance AF. Therefore, there are concerns regarding prescriptions of anticoagulants to patients with AF and CKD. The worsening in kidney function can be effectively due to anticoagulants administration. Warfarin has been recognized to promote acute kidney injury in case of excessive anticoagulation levels. Nevertheless, further mechanisms can induce the chronic worsening of renal function, thus leading to terminal kidney failure as observed in post-hoc analysis from registration trials and dedicated observational studies. By contrast, DOACs seem to protect kidneys from injuries more efficiently than Warfarin, although they still continue to play a role in promoting some kidney lesions. However, the exact mechanisms remain unknown. This narrative review aimed to discuss the influence of oral anticoagulants on renal impairment as well as to overview potential pathophysiological mechanisms related to this clinical complication.

Acute Kidney Injury due to Anticoagulant-Related Nephropathy : A Suggestion for Therapy

The relationship between kidneys and anticoagulation is complex, especially after introduction of the direct oral anticoagulants (DOAC). It is recently growing evidence of an anticoagulant-related nephropathy (ARN), a form of acute kidney injury caused by excessive anticoagulation. The pathogenesis of kidney damage in this setting is multifactorial, and nowadays, there is no established treatment. We describe a case of ARN, admitted to our Nephrology Unit with a strong suspicion of ANCA-associated vasculitis due to gross haematuria and haemoptysis; the patient was being given dabigatran. Renal biopsy excluded ANCA-associated vasculitis and diagnosed a red blood cell cast nephropathy superimposed to an underlying IgA nephropathy. Several mechanisms are possibly responsible for kidney injury in ARN: tubular obstruction, cytotoxicity of heme-containing molecules and free iron, and activation of proinflammatory/profibrotic cytokines. Therefore, the patient was given a multilevel strategy of treatment. A combination of reversal of coagulopathy (i.e., withdrawal of dabigatran and infusion of its specific antidote) along with administration of fluids, sodium bicarbonate, steroids, and mannitol resulted in conservative management of AKI and fast recovery of renal function. This observation could suggest a prospective study aiming to find the best therapy of ARN.

Systematic DOACs oral anticoagulation in patients with atrial fibrillation and chronic kidney disease: the nephrologist's perspective

Atrial fibrillation (AF) is highly prevalent among patients with chronic kidney disease (CKD), and also associated with unfavorable outcome. Anticoagulant therapy is the mainstep of management in such patients, aimed at reducing the high risk of systemic thromboembolism and especially of ischemic stroke, which is reportedly associated with increased mortality in CKD patients. Even though new direct oral anticoagulant agents (DOACs) proved to be effective in patients with non valvular chronic AF, and are therefore recommended by recent guidelines for their treatment, warfarin is currently used in more than one-half of subjects needing oral anticoagulation, and only 30% of them are converted from a vitamin K antagonist- to a DOAC-based regimen. The main reason for not prescribing DOACs is often a reduction in renal function, even if mild. Aim of this review was therefore to evaluate the impact of DOAC therapy in the setting of CKD, from a nephrological perspective, by comparing available evidence on the role of DOACs in patients with CKD and AF with that emerging from traditional warfarin-based therapy. Both the pathogenesis of AF in CKD, and available findings of renal, cardiovascular and bone effects of DOACs in CKD are discussed, leading to the conclusion that DOAC therapy should be considered as the first line therapy for non valvular AF in patients with mild and moderate reduction of renal function, and could also be adopted for patients with severe CKD not on hemodialysis treatment, whereas there is insufficient evidence for ESRD patients on dialysis.

Dabigatran-induced anticoagulant-related nephropathy with undiagnosed IgA nephropathy in a patient with normal baseline renal function

Occasionally, over-anticoagulation with warfarin induces acute kidney injury (AKI) characterized by glomerular hemorrhage with tubular obstruction by red blood cell casts, which is widely acknowledged as warfarin-related nephropathy. Owing to extensive use of direct oral anticoagulants, similar AKI cases have been reported among patients treated with dabigatran. Dabigatran is primarily excreted by the kidneys; thus, renal impairment is one of the risk factors for dabigatran-induced bleeding complications. Nevertheless, risk factors for dabigatran-induced anticoagulant-related nephropathy (ARN) remain partially clarified. Here, we report a histologically established case of dabigatran-induced ARN with undiagnosed IgA nephropathy in a patient with normal baseline renal function. In addition, we summarize previously published cases of biopsy-proven, dabigatran-related ARN. A 67-year-old female with normal preexisting renal function developed macrohematuria and AKI. She had been treated with dabigatran for deep vein thrombosis. A renal biopsy diagnosed ARN with inactive IgA nephropathy. After dabigatran withdrawal, her macrohematuria and renal function improved. This report demonstrates that ARN could occur in patients with normal baseline renal function. Our case and prior reports suggest that IgA nephropathy could be a risk factor for dabigatran-induced ARN.

Anticoagulant-Related Nephropathy in Kidney Biopsy: A Single-Center Report of 41 Cases

Rationale & Objective

In 2009, the first case of acute kidney injury and occlusive red blood cell (RBC) tubular casts associated with a high international normalized ratio in a patient receiving warfarin was identified. This entity, named warfarin-related nephropathy, was later renamed anticoagulant-related nephropathy (ARN) after similar cases with other anticoagulants were described. We provide our 10-year experience with ARN based on a single-center kidney biopsy laboratory.

Study Design

The kidney pathology database at the Ohio State University Wexner Medical Center (OSUWMC) was searched for native kidney biopsy cases consistent with ARN. Clinical data were obtained from patient medical records.

Setting & Participants

Native kidney biopsies evaluated between January 1, 2009, and December 31, 2017 at OSUWMC.

Results

Among 8,636 native kidney biopsies reviewed at the OSUWMC, there were 41 (0.5%) patients for whom deterioration in kidney function could not be explained by kidney biopsy findings alone if anticoagulation was not considered. There were 63% men and 95% were white; average age was 62 ± 14 years. Most were on warfarin therapy (N = 28), although cases were also attributed to direct-acting anticoagulants (N = 2), antiplatelet medications (N = 1), heparin or enoxaparin (N = 4), and disseminated intravascular coagulopathy (N = 6). Morphologically, there was acute tubular necrosis and RBC casts. The majority of biopsies had an underlying glomerular disease and many patients had positive serologic test results. In all these cases, the severity of kidney failure, RBC tubular casts, and hematuria were disproportionate to glomerular morphologic changes.

Limitations

Selection bias in the decision to perform a kidney biopsy.

Conclusions

ARN is an uncommon diagnosis in kidney pathology practice, but it should be considered when the number of RBC tubular casts is disproportionate to the severity of glomerular changes in a kidney biopsy in patients either receiving anticoagulation therapy or who presented with acute coagulopathy. Our data suggest that anticoagulation aggravates underlying glomerular diseases rather than directly affecting the glomerular filtration barrier.

Rivaroxaban-related acute kidney injury in a patient with IgA vasculitis

Anticoagulants have recently been recognised as a cause of acute kidney injury (AKI). We describe the case of a 75-year-old man with IgA vasculitis and atrial fibrillation treated with rivaroxaban, who presented with macroscopic haematuria and an acute decline in renal function. Two months before referral, he noted palpable purpuric lesions and was diagnosed with IgA vasculitis based on skin biopsy findings; the skin lesion disappeared following treatment with a steroid external preparation. Renal biopsy revealed glomerular haemorrhage and red blood cell casts. Although rivaroxaban was withdrawn, his kidney function worsened and he was started on haemodialysis. His renal function did not recover. To the best of our knowledge, this is the first case of direct oral anticoagulant (DOAC)-related AKI in systemic vasculitis. During DOAC therapy, close monitoring of a patient's urinalysis results and their renal function may be required for patients with systemic vasculitis to avoid AKI.

Dabigatran causing severe acute kidney injury in a patient with liver cirrhosis

Anticoagulant-related nephropathy (ARN), a significant but frequently undiagnosed problem in patients receiving anticoagulation, is found to be associated with increased renal morbidity and all-cause mortality. While ARN is mainly associated with warfarin use, recent case reports suggest that it may also occur in patients taking direct oral anticoagulants (DOAC). We report a patient who had a history of alcoholic liver cirrhosis and paroxysmal atrial fibrillation, and received dabigatran 110 mg twice daily for 1 year. He presented with gross hematuria and severe acute kidney injury with an international normalized ratio of 4.09. Dabigatran was stopped and he was put on temporary hemodialysis support. His renal function gradually improved when the hematuria subsided. Renal biopsy later confirmed the presence of red blood cell casts inside the renal tubules with features of IgA nephropathy. Finally, his renal function returned back to baseline level. As DOAC has been increasingly used nowadays for the treatment of various thromboembolic diatheses, regular monitoring of renal function is warranted, especially in patients with underlying glomerular diseases and coagulopathy such as chronic liver diseases.

Anticoagulant Related Nephropathy Induced by Dabigatran

We describe a case of biopsy-proven dabigatran related nephropathy in a patient without underlying IgA nephropathy. To date, dabigatran related nephropathy was only reported in patients with concurrent or undiagnosed IgA nephropathy, suggesting that it may predispose patients to dabigatran associated injury. The patient is an 81-year-old woman with multiple medical comorbidities, including nonvalvular atrial fibrillation, who was anticoagulated with dabigatran. She presented to hospital with acute kidney injury in the setting of volume overload. Her estimated glomerular filtration rate decreased from a baseline of 57 mL/min/1.73 m² to 4 mL/min/1.73 m², necessitating hemodialysis. Renal ultrasound findings, fractional excretion of sodium, and urinalysis suggested acute kidney injury. Renal biopsy showed acute tubular injury, tubular red blood cell casts, and an absence of active glomerulonephritis, similar to the pathological findings of warfarin related nephropathy. A diagnosis of anticoagulant related nephropathy secondary to dabigatran was therefore established. This case demonstrates that dabigatran, like warfarin, may increase tubular bleeding risk in patients, irrespective of underlying kidney or glomerular disease.

Dabigatran-induced nephropathy and its successful treatment with Idarucizumab - case report and literature review

BACKGROUND

Anticoagulant induced renal injury has been previously described with Warfarin treatment. In the last decade direct oral anticoagulants (DOAC) were introduced. They include direct inhibitors of factor Xa (Rivaroxaban, Apixaban, Edoxaban) and a thrombin inhibitor (Dabigatran). There are isolated reports describing acute kidney injury (AKI) due to the use of DOACs.

CASE REPORT

We report a clinical case of an 80-year-old patient recently started on Dabigatran for new onset atrial fibrillation. She presented with AKI and hematuria, urine specimen showed RBC casts, and a working diagnosis of anticoagulant nephropathy due to Dabigatran was made. During hospitalization she was treated with Idarucizumab with a full recovery of renal function. To the best of our knowledge, there are 4 published case reports describing kidney injury produced by Dabigatran.

CONCLUSION

The use of DOACs is increasing rapidly, with increasing concern about its safety profile and, in particular, its potential harmful effect on renal function. As described in our case, treatment with Praxbind for Dabigatran induced kidney injury may be an acceptable management strategy that may obviate the need for urgent dialysis in selected cases by complete reversal of the AKI.

Impact of Altered Intestinal Microbiota on Chronic Kidney Disease Progression

In chronic kidney disease (CKD), accumulation of uremic toxins is associated with an increased risk of CKD progression. Some uremic toxins result from nutrient processing by gut microbiota, yielding precursors of uremic toxins or uremic toxins themselves, such as trimethylamine N-Oxide (TMAO), p-cresyl sulphate, indoxyl sulphate and indole-3 acetic acid. Increased intake of some nutrients may modify the gut microbiota, increasing the number of bacteria that process them to yield uremic toxins. Circulating levels of nutrient-derived uremic toxins are associated to increased risk of CKD progression. This offers the opportunity for therapeutic intervention by either modifying the diet, modifying the microbiota, decreasing uremic toxin production by microbiota, increasing toxin excretion or targeting specific uremic toxins. We now review the link between nutrients, microbiota and uremic toxin with CKD progression. Specific focus will be placed on the generation specific uremic toxins with nephrotoxic potential, the decreased availability of bacteria-derived metabolites with nephroprotective potential, such as vitamin K and butyrate and the cellular and molecular mechanisms linking these toxins and protective factors to kidney diseases. This information provides a conceptual framework that allows the development of novel therapeutic approaches.

Acute kidney injury and undiagnosed immunoglobulin A nephropathy after dabigatran therapy

Dabigatran, a new oral anticoagulant, is a direct thrombin inhibitor used as an alternative to warfarin to reduce the risk of stroke and systemic embolism with nonvalvular atrial fibrillation. We report a case of a man who resumed dabigatran after 6 weeks of prior therapy and began experiencing hematuria with worsening kidney function. Renal biopsy with immunofluorescence and electron microscopy showed mesangial deposits consistent with immunoglobulin A nephropathy. With discontinuation of dabigatran and addition of methylprednisolone, the gross hematuria cleared and urine output improved.

Warfarin-related Nephropathy

Warfarin-related nephropathy also referred to as anticoagulant-related nephropathy (ACRN) is a type of acute kidney injury (AKI) that may be caused by excessive anticoagulation with warfarin and other anticoagulants. Despite the well-described histological entity, the clinical course and approach to ACRN in patients requiring life-long anticoagulation are however not well described in the literature. We report a 50-year-old Indian woman who was on prolonged anticoagulant therapy post-mitral valve replacement. She presented with AKI, and renal biopsy was suggestive of ACRN. Steroids were given and her creatinine levels reached within the normal range in 2 weeks. A presumptive diagnosis of ACRN should be made if a severe warfarin coagulopathy is present and if other causes of AKI have been excluded, in patients with chronic anticoagulant therapy. Renal function should be monitored regularly in patients who are on anticoagulant therapy.

Anticoagulant-related nephropathy in a patient with IgA nephropathy

Anticoagulant-related nephropathy is a type of acute kidney injury caused by overcoagulation. We describe a case of an 84-year-old man with arterial hypertension, coronary heart disease and atrial fibrillation treated with acenocoumarol, who presented with haematoproteinuria and acute kidney injury during a phase of excessive anticoagulation. In addition to IgA nephropathy, renal biopsy also revealed acute tubular necrosis, red blood cell casts and positive iron staining in tubular cells. After this acute episode, renal function improved and proteinuria decreased below the nephrotic range.

Warfarin-related nephropathy induced by three different vitamin K antagonists: analysis of 13 biopsy-proven cases

Background: Acute kidney injury (AKI) with renal tubular obstruction by red blood cell casts (RBCC) has been described in patients treated with warfarin and is known as warfarin-related nephropathy (WRN).

Methods: To determine whether other vitamin K antagonists (VKA) cause WRN, we retrospectively collected and analyzed the clinical and histological data of 13 patients treated with different VKA (seven with fluindione, four with warfarin and two with acenocoumarol) in seven French hospitals.

Results: They all developed gross hematuria following overanticoagulation complicated by severe AKI (median serum creatinine concentration = 693 μmol/L). Histological analysis of the kidney biopsies highlighted the presence of intratubular RBCC and acute tubular necrosis in all patients and of an underlying kidney disease in 12 patients. WRN was suspected in patients treated with warfarin; however, the initial diagnosis was incorrect in six of the nine patients treated with other VKA. Nine patients progressed to chronic kidney disease, one fully recovered renal function, two died and one still needs dialysis.

Conclusions: This is the first report of AKI caused by fluindione. In agreement with the recent publication on AKI in two patients treated with dabigatran, we suggest that the term ‘anticoagulant-related nephropathy’ is more appropriate than WRN. Gross hematuria in patients with an underlying kidney disease and treated with VKA requires rapid control of the international normalized ratio and renal function monitoring.

Anticoagulation-related nephropathy

Anticoagulation-related nephropathy (ARN) is a significant but underdiagnosed complication of anticoagulation that is associated with increased renal morbidity and all-cause mortality. Originally described in patients receiving supratherapeutic doses of warfarin who had a distinct pattern of glomerular hemorrhage on kidney biopsy, ARN is currently defined as acute kidney injury (AKI) without obvious etiology in the setting of an International Normalized Ratio (INR) of > 3.0. The underlying molecular mechanism is thought to be warfarin-induced thrombin depletion; however, newer studies have hinted at an alternative mechanism involving reductions in activated protein C and endothelial protein C receptor signaling. Prompt recognition of ARN is critical, as it is associated with accelerated progression of chronic kidney disease, and significant increases in short-term and long-term all-cause mortality. Prior investigations into ARN have almost universally focused on anticoagulation with warfarin; however, recent case reports and animal studies suggest that it can also occur in patients taking novel oral anticoagulants. Differences in the incidence and severity of ARN between patients taking warfarin and those taking novel oral anticoagulants are unknown; a post hoc analysis of routinely reported adverse renal outcomes in clinical trials comparing warfarin and novel oral anticoagulants found no significant difference in the rates of AKI, a prerequisite for ARN. Given the significant impact of ARN on renal function and all-cause mortality, a thorough understanding of the pathophysiology, molecular mechanisms, clinical spectrum and therapeutic interventions for ARN is crucial to balance the risks and benefits of anticoagulation and optimize treatment.

Acute kidney injury due to glomerular haematuria and obstructive erythrocyte casts associated with thrombocytopaenia and thin basement membrane disease: a case report

Background

Acute kidney injury due to glomerular bleeding has been described with IgA nephropathy and supratherapeutic warfarin anticoagulation. There is usually demonstrable tubular obstruction by erythrocyte casts associated with acute tubular injury. Although severe thrombocytopaenia increases the risk of bleeding, most cases of haematuria have been ascribed to non-glomerular or urological bleeding without a direct link to acute kidney injury. We describe a patient with acute kidney injury due to glomerular bleeding and tubular injury related to severe thrombocytopaenia, who was subsequently found to have thin basement membrane disease.

Case presentation

A 56 year old man presented with macroscopic haematuria, acute kidney injury and a platelet count of 35 × 10⁹/L, in the absence of anticoagulation. Urinalysis demonstrated an active urinary sediment. His kidney biopsy demonstrated extensive intraluminal erythrocyte casts associated with acute tubular injury, along with haemosiderin deposition suggestive of recurrent glomerular bleeding. There was no histological evidence of glomerular pathology but electron microscopy analysis demonstrated thin basement membrane disease and effacement of podocyte foot processes. During long term follow-up, thrombocytopaenia and intermittent haematuria persisted. At 9 months, the patient progressed to Stage 5 chronic kidney disease with the development of gross renal atrophy.

Conclusion

Recurrent macroscopic haematuria may be a risk factor for progressive renal injury in patients with thin basement membrane. The mechanism may be due to recurrent acute kidney injury from glomerular bleeding leading to repeated tubular damage. In the absence of anticoagulation, severe thrombocytopaenia may be a risk factor for heavy glomerular bleeding and acute kidney injury in these patients.

Dabigatran-Related Nephropathy in a Patient with Undiagnosed IgA Nephropathy

Dabigatran is a direct thrombin inhibitor used as an alternative to warfarin for long term anticoagulation. Warfarin-related nephropathy is an increasingly recognized entity, but recent evidence suggests that dabigatran can cause a WRN-like syndrome. We describe a case of a biopsy-proven anticoagulant nephropathy related to dabigatran in a patient with IgA nephropathy and propose that, despite the base glomerular disease, acute kidney injury was due to tubular obstruction by red blood cells and heme-associated tubular injury, and through a mechanism involving inhibition of anticoagulation cascade and barrier abnormalities caused by molecular mechanisms.