Relationship between proteinuria and venous thromboembolism

Nephrotic syndrome is known to cause venous thromboembolism (VTE) due to urine loss of antithrombin III and activation of the coagulation system. We hypothesized that the degree of proteinuria may predict the development of VTE. This was a retrospective case-controlled study of in-patients urban academic teaching hospital from April, 2007 to March, 2009 and who had undergone an imaging study for VTE. All radiology reports (N = 1,647) for CT angiography of chest and Doppler sonogram of extremities were reviewed. The following data were collected: race/ethnicity, degree of proteinuria on urinalysis, serum protein and albumin levels, risk factors for VTE and renal function. The study population consisted of 284 patients with VTE and 280 age/sex matched controls. Relative to those who did not have proteinuria, patients who tested positive for protein had a 3.4-fold increased risk of VTE (odds ratio (OR) 3.4, 95% confidence interval [2.4, 5.0]). The association was unchanged when adjusted for other risk factors. Patients with proteinuria may have an increased risk of venous thromboembolism.