Recovery of renal function after bilateral renal vein thrombosis episode as complication of membranous glomerulopa-thy : case report

A 33-year-old male patient, previously healthy and without known comorbidities, was admitted to the Nephrology Service of the General Hospital of Fortaleza (HGF), complaining of gastric fullness, lower limb edema, unproductive cough and frothy urine for three months. He also reported dyspnea on average efforts progressing to great efforts 15 days from admission. He had a weight loss of 10 kg in this period. Good general condition, eupneic, alert and oriented; small, palpable, mobile, fibroelastic lymph node with approximately one centimeter in the left posterior DOI: 10.5935/0101-2800.20170085 Renal vein thrombosis (RVT) is a complication often associated with nephrotic syndrome. It occurs due to a state of hypercoagulability common in the diseases that attend to this syndromic diagnosis. It should be suspected whenever there is nephrotic syndrome associated with sudden flank pain, hematuria and worsening of proteinuria. Bilateral RVT also presents with frequently oliguric renal dysfunction. This case reports a 33-year-old patient hospitalized for a nephrotic syndrome, with etiologic investigation suggestive of primary membranous glomerulopathy, which evolved with bilateral RVT associated with deterioration of renal function and need for renal replacement therapy. He promptly performed angiography with thrombectomy and thrombolysis, evolving with recovery of renal function in two weeks. abstraCt

Renal vein thrombosis (RVT) is a complication often associated with nephrotic syndrome.It occurs due to a state of hypercoagulability common in the diseases that attend to this syndromic diagnosis.It should be suspected whenever there is nephrotic syndrome associated with sudden flank pain, hematuria and worsening of proteinuria.Bilateral RVT also presents with frequently oliguric renal dysfunction.This case reports a 33-year-old patient hospitalized for a nephrotic syndrome, with etiologic investigation suggestive of primary membranous glomerulopathy, which evolved with bilateral RVT associated with deterioration of renal function and need for renal replacement therapy.He promptly performed angiography with thrombectomy and thrombolysis, evolving with recovery of renal function in two weeks.abstraCt Keywords: glomerulonephritis, membranous; proteinuria; venous thrombosis.
Laboratory tests included albumin 2.5 mg/dl, and non-reactive FAN and ANTI-DNA, and negative cryoglobulinemia.Non-reactive serologies for HIV, hepatitis B, hepatitis C and syphilis.Complement within normal ranges, erythrocyte sedimentation rate 140 mg/dl and PCR 8.5 mg/dl.Protein electrophoresis with absence of monoclonal peak.The remaining laboratory tests are described in Table 1.
Urinary tract ultrasonography (US) evidenced slightly increased kidneys (RD: 13.8 x 6.8 x 5.8cm Parenchyma 1.5cm -RE: 13 x 7.1 x 6.1cm -Parenchyma: 1,5cm) and increased cortical echogenicity, suggestive of parenchymal nephropathy with no stones.She undertook investigation of secondary causes of nephrotic syndrome that were all negative, and a renal biopsy was performed, which was suggestive of membranous glomerulopathy, according to the light microscopy illustrated in Figure 1.
After 1 week of admission, he was submitted to another complete abdomen US, due to an ill-defined abdominal pain, which showed signs suggestive of thrombosis of the right renal vein.After that, full anticoagulation with continuous infusion of heparin was initiated; on the following day, the patient developed anuria for more than 12 hours, nausea, two emetic episodes, two febrile episodes (37.8ºC and 38.1ºC) and worsening of nitrogenous slags (creatinine 5.6 and urea 60), with suspicion of bilateral renal vein thrombosis.The patient was submitted to renal angiography (arteriography and phlebography), which confirmed the hypothesis of bilateral renal vein thrombosis (Figure 2).Bilateral thrombectomy and thrombolysis were performed on the left and the patient was maintained in anticoagulation (initially with heparin and subsequently with warfarin).
The patient remained on hemodialysis for two weeks, evolving with progressive improvement in diuresis and renal function.He was discharged with renal function recovery, creatinine of 1.66 mg/dl.First outpatient visit after discharge the patient had creatinine of 0.77mg/dl.

DisCussion
Renal vein thrombosis (RVT) was described by Rayer in 1840 and its association with nephrotic syndrome (NS) was first reported in 1939 by Doroe, Schlesinger and Savitz. 1 Initially, there were conflicting reports about the cause and effect relationship of the RVT in the NS, but in the last years RVT was better described as a consequence of NS. 2 RVT is seen more frequently in membranous glomerulopathies and membranoproliferative than in other types, such as minimal lesion and FSGS. 3 Advanced age, membranous nephropathy, severe proteinuria and hypoalbuminemia are recognized as increased risk factors for the development of thromboembolism. 4he RVT pathogenic mechanism in the NS is not fully understood, but it is established that the NS is associated with a state of hypercoagulability, and it is further reinforced by urinary loss and, consequently, reduced serum antithrombin level III. 5 The clinical condition results from the balance between acute occlusion, extension of thrombosis and development of collateral circulation.The acute presentation of renal vein thrombosis is infrequent and is mainly characterized by acute flank pain and hematuria.The laboratory findings that may suggest RVT are proteinuria (significant increase after event), increase in serum creatinine, hematuria, glycosuria, pyuria, hyperchloremic acidosis.6,7 In most cases, the patients are asymptomatic, making the RVT underdiagnosed.8 Early diagnosis is essential because it is a reversible condition.The gold standard diagnostic test is renal phlebography, but USG with renal vein Doppler and contrast abdominal CT have been fast and safe noninvasive measurements for the direct visualization of the thrombus.9,10 The recommended treatment is full anticoagulation, which should be started immediately.The current recommendation is to begin with heparinization and after combining warfarin, and the total time for anticoagulation for a first episode of venous thromboembolism is at least 3-6 months, and until the cause of NS has been resolved or is in remission.11,12 In relation to the new oral anticoagulants (direct factor Xa inhibitors and direct thrombin inhibitor), warfarin anticoagulation is already recommended as an option in the treatment of general deep venous thromboembolism and pulmonary embolism.13,14 The great limitation in the use of these medications is the impossibility of using them in patients with creatinine clearance lower than 15ml/min.15 Thrombolysis has not been fully studied in NSassociated thromboembolism.Most of the evidence for its use has been derived from reports and series of cases that are generally of limited value.Therefore, most experts recommend thrombolytic therapy for severe bilateral RVT or massive pulmonary embolism.16 The reported case illustrates an acute presentation of left-sided RVT, with probably chronic right RVT,

Figure 1 .
Figure 1.Light microscopy of the renal biopsy fragments -silver staining -evidencing thickening of glomerular basement membrane with spicules.
in a patient with NS.The patient did not present the classical clinical signs.Bilateral RVT was suspected due to anuria and sudden worsening of renal function.The venogram, gold standard, was performed to obtain the diagnosis, as well as the therapeutic intervention, with bilateral thrombectomy and thrombolysis located in the left renal vein.There was modest improvement in renal flow immediately and complete recovery of renal function after two weeks of the event.

table 1
Laboratory tests performed during hospitaLization