Pulmonary embolism and renal vein thrombosis in patients with nephrotic syndrome: Prospective evaluation of prevalence and risk factors with CT

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

Materials and Methods: 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 and renal CT venography for RVT. Prevalence of PE and/or RVT was estimated for different ages, sexes, and histopathologic types of nephrotic syndrome. Multivariate analysis was used to determine independent predictors for PE and/or RVT in patients with nephrotic syndrome.

Results: 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 and/or RVT, with PE the more common condition (85% [153 of 180]). PE was associated with RVT in 85 (56%) of 153 patients and was isolated in 68 patients (44%). Most patients with PE (84% [128 of 153]) were asymptomatic. One hundred twelve (22%) of 505 patients had RVT. PE and/or RVT was found in 15 (19%) of 80 children with nephrotic syndrome, while 165 (38%) of 432 adult patients with nephrotic syndrome had PE and/or RVT (P = .001). Membranous nephropathy was the most common histopathologic type associated with PE and/or RVT (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 and/or RVT (P < 05 for all).

Conclusion: PE and RVT are common in patients with nephrotic syndrome. PE is more common than RVT, 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.