# Managing Pulmonary Embolism Associated With Renal Vein Thrombosis During Nephrotic Syndrome: Usefulness of Rivaroxaban Level Monitoring

## TL;DR

A patient with nephrotic syndrome developed pulmonary embolism and renal vein thrombosis, and was successfully treated with rivaroxaban while monitoring drug levels due to concerns about proteinuria affecting drug concentration.

## Contribution

Demonstrates the usefulness of monitoring rivaroxaban levels in nephrotic syndrome patients with thromboembolic events.

## Key findings

- Rivaroxaban plasma concentrations correlated strongly with the extent of proteinuria in the patient.
- The patient showed complete resolution of thrombotic formations after rivaroxaban treatment.
- Monitoring drug levels is suggested to be useful during significant proteinuria periods in nephrotic syndrome.

## Abstract

This case report presents a scenario of pulmonary embolism (PE) and renal vein thrombosis (RVT) in a young patient with a recent diagnosis of nephrotic syndrome (NS). The presence of a clinical condition characterised by a marked non‐selective proteinuria, which may correlate with reduced drug concentration, has raised doubts about the most appropriate anticoagulant therapeutic choice. A 34‐year‐old male patient presented to the emergency department with dyspnea, chest pain and hypotension. Two days prior, the patient had undergone a renal biopsy for a recent NS finding. An urgent CT scan revealed a right pulmonary embolism and inferior left renal vein thrombus, prompting immediate anticoagulant therapy. The patient was discharged on rivaroxaban. The presence of NS and the consequent concern regarding potential decreased drug concentration led us to monitor rivaroxaban plasma concentrations during the treatment period. Monitoring showed a strong correlation between the extent of proteinuria and the drug concentration. At the 4‐month follow‐up after discharge from the hospital, the patient was performing normal daily activities without limitations, and angio‐CT showed complete resolution of renal and pulmonary thrombotic formations. In this clinical case, pulmonary embolism associated with renal vein thrombosis in a patient with a recent diagnosis of NS was managed with rivaroxaban with a good clinical outcome.

This clinical experience confirms the efficacy and safety of rivaroxaban for the treatment of thromboembolic events in patients with nephrotic syndrome but also suggests the usefulness of monitoring drug levels when the embolic event occurs during a period of significant proteinuria, such as at the time of nephrotic syndrome diagnosis.