Risk factors of worsening kidney function and mortality in patients with renal vein thrombosis: a retrospective study

The outcome of renal vein thrombosis, in particular as for the long-term impact on kidney function, is not fully known. We aimed to study the natural course and outcomes of patients with renal vein thrombosis, in a large, single-center cohort.

A single-center retrospective cohort study including patients who were diagnosed with renal vein thrombosis between January 2006 and September 2021 was analyzed. The main outcomes analyzed were worsening kidney function, defined as a decrease in eGFR of at least 40% from baseline, and all-cause mortality.

Eighty-seven patients were included, 56.3% were female, median age was 57 years. Malignancy was the most common cause of renal vein thrombosis (60.9%), followed by post-surgery and trauma (16.1%) and nephrotic syndrome (12.6%). At initial presentation, 65.5% of the patients were asymptomatic; the main signs and symptoms were gross hematuria (20.7%), flank pain (18.4%), and flank tenderness (9.2%). During follow-up, 18 (21.4%) patients experienced worsening kidney function and 57 (65.5%) died. Multivariable analyses showed that the risk of worsening kidney function was higher in patients with nephrotic syndrome (hazard ratio [HR] 18.41; 95% confidence interval [CI], 1.57-216.04), body weight ≥ 60 kg (HR 4.82; 95% CI 1.43-16.32), and malignancy (HR 9.10; 95% CI 1.05-78.63). Symptomatic acute renal vein thrombosis was associated with a lower risk of worsening kidney function compared to asymptomatic or symptomatic chronic renal vein thrombosis (HR 0.12; 95% CI 0.01-0.96). Malignancy (HR 5.45; 95% CI 2.58-11.54), age ≥ 75 years (HR 3.44; 95% CI 1.49-7.93), and serum albumin < 3.0 g/dL (HR 2.88; 95% CI 1.65-5.05) were associated with an increased mortality risk.

Renal vein thrombosis is associated with a high rate of worsening kidney function and mortality. It is crucial to promptly identify patients at high risk and initiate early treatment to prevent negative outcomes.