A 39-year-old Mexican man with a history of rheumatoid arthritis and diabetes presented with 5 days of abdominal pain. Pain was peri-umbilical without radiation. He had not taken any prescription medications for more than a year. He smoked cigarettes for more than 20 years, but denied use of alcohol or illicit drugs. He also denied nausea, vomiting, diarrhea, fevers, or chills. He had noted no changes in his urine.
Temperature was 37.2, pulse 73, blood pressure 113/70. Abdomen was tender to palpation throughout and non-distended, with normoactive bowel sounds. There was trace lower extremity edema. Thickening was noted around all proximal interphalangeal joints without synovitis.
White blood cell count was 7.8, AST 33, ALT 28, Alkaline Phosphatase 163, and albumin 2.0. Urinalysis showed a protein level of greater than 600 mg/dl and a urine protein/creatinine ratio of 8.58. HIV, Hep B and Hep C serologies were negative.
CT abdomen and pelvis showed left renal vein thrombus, extending into the IVC with enlargement of the left kidney. (Figure 1)
The patient was started on systemic anti-coagulation with a continuous heparin infusion. Rheumatologic studies returned a positive ANA with titer greater than 1:640 speckled pattern, positive rheumatoid factor, positive CCP antibody, and undetectable C3 and C4 levels. Nephrology performed a kidney biopsy that later revealed membranous lupus nephritis (class V). His abdominal pain improved and he was transitioned to Xarelto upon discharge.
Discussion:
The general internist should be aware of renal vein thrombosis as a potential complication of nephrotic syndrome. The risk of developing arterial or venous thrombosis is approximately eight times higher than the general population, and the risk is typically greatest within the first six months of diagnosis of nephrotic syndrome. Renal vein thrombosis occurs in approximately one third of patients with nephrotic syndrome, but the prevalence has been found to range from 5 to over 60 percent.
Based upon data from the Glomerular Disease Collaborative Network and the Toronto Glomerulonephritis Registry, the risk of thrombosis is related to the severity of hypoalbuminemia. The risk of thrombosis is much higher with a serum albumin concentration less than or equal to 2.8 (adjusted relative risk of 2.5).
In Class V lupus nephritis, as in our patient, it is common to present with signs of nephrotic syndrome as well as thrombotic complications of renal vein thromboses or pulmonary emboli. An online tool, http://www.unckidneycenter.org/gntools/index.html, is available to aid clinicians in estimating the individual risk for patients to help tailor prophylactic anticoagulation. When treating patients with renal venous thrombosis in the setting of nephrotic syndrome, it is preferred to continue systemic anticoagulation for a minimum of 6 to 12 months, or as long as the patient remains with active nephrotic range proteinuria.
Conclusions:
Renal vein thrombosis is a common complication of nephrotic syndrome, and the risk of developing thrombosis is related to the severity of hypoalbuminemia. Treatment is typically systemic anticoagulation for 6 to 12 months or until patient no longer has active nephrotic range proteinuria.