Which is more commonly associated with renal thrombosis, Membranous Glomerulonephritis (MGN) or Membranoproliferative Glomerulonephritis (MPG)?

Membranous Glomerulonephritis (MGN) is More Commonly Associated with Renal Thrombosis

Membranous Glomerulonephritis (MGN) is more commonly associated with renal thrombosis compared to Membranoproliferative Glomerulonephritis (MPGN), with MGN having a specific disease-related thrombotic risk independent of other factors. 1

Thrombotic Risk in Glomerular Diseases

Membranous Glomerulonephritis (MGN)

• MGN has a specific disease-related risk for venous thromboembolism that persists even after adjustment for gender, degree of proteinuria, serum albumin level, and history of malignancy 1
• The KDIGO guidelines specifically highlight that MGN is associated with an increased risk of thromboembolism compared to other nephrotic syndromes like FSGS and IgA nephropathy 1
• Extrarenal effects more common in MGN include accelerated vascular disease and an increased risk of thromboembolism 1
• The mechanisms underlying this disease-specific risk of venous thromboembolism in MGN are not fully understood 1

Risk Factors for Thrombosis in MGN

• Serum albumin level below 2.8 g/dL is identified as a threshold for overall thrombotic risk 1
• Marked reduction in serum albumin (<2.5 g/dl) with additional risk factors warrants consideration for prophylactic anticoagulant therapy 1
• Most thromboembolic events occur within the first 6 months after diagnosis of nephrotic syndrome 1

Comparative Thrombotic Risk

While some older studies showed similar rates of renal vein thrombosis in both conditions:

• In a 1975 study, among 12 patients with renal vein thrombosis, 10 had membranous glomerulonephritis and only 2 had membranoproliferative glomerulonephritis 2
• In a 1977 study, 8 of 21 patients (38%) with either MGN or MPGN had renal vein thrombosis 3

However, more recent guidelines specifically identify MGN as having a unique thrombotic risk profile that distinguishes it from other glomerular diseases including MPGN.

Management Implications

Anticoagulation Recommendations

• KDIGO guidelines suggest that patients with MGN and nephrotic syndrome with marked reduction in serum albumin (<2.5 g/dl) and additional risks for thrombosis should be considered for prophylactic anticoagulant therapy using oral warfarin 1
• Anticoagulation is warranted in patients who initially present with a thrombotic event such as renal vein thrombosis or pulmonary embolism 1
• Anticoagulation can typically be discontinued when nephrotic syndrome resolves, as the thrombophilia should gradually resolve 1

Monitoring for Thrombotic Complications

• Regular monitoring for thromboembolic complications is essential in patients with MGN
• Patients with MGN should be educated about symptoms of thrombosis and pulmonary embolism
• Consider lower threshold for imaging studies to detect renal vein thrombosis in patients with MGN compared to MPGN

Clinical Pearls and Pitfalls

Pearls

• MGN is the most frequent glomerular lesion associated with malignancy, particularly in elderly patients 4
• MGN is seen more frequently in men (male/female ratio 2-3:1) and presents most commonly between ages 40-60 1
• Complete spontaneous remission occurs in 20-30% of MGN cases and is more likely in patients with subnephrotic proteinuria and in women 1

Pitfalls to Avoid

• Failing to evaluate for underlying causes of MGN (malignancy, autoimmune disease, infections) before initiating treatment
• Overlooking the need for prophylactic anticoagulation in high-risk MGN patients
• Assuming all nephrotic syndromes carry equal thrombotic risk - MGN has a unique risk profile

In conclusion, while both MGN and MPGN can be associated with renal thrombosis, current evidence and guidelines indicate that MGN carries a higher and more specific risk for thrombotic complications, particularly renal vein thrombosis, independent of other risk factors.