# Successful treatment of coexisting membranous nephropathy and immune thrombocytopenia by eradicating gastric Helicobacter pylori infection: a case report

## TL;DR

A patient with kidney disease and low platelets improved after treating a stomach infection caused by Helicobacter pylori.

## Contribution

This case report demonstrates that eradicating Helicobacter pylori can treat coexisting membranous nephropathy and immune thrombocytopenia.

## Key findings

- The patient's kidney disease and low platelet count improved after H. pylori eradication.
- No immunosuppressive treatment was needed after H. pylori infection was cleared.
- IgG4 was the predominant subclass deposited in the glomeruli.

## Abstract

Membranous nephropathy (MN) is a common cause of nephrotic syndrome in middle-aged and older adults. MN etiology is mainly primary or idiopathic; however, it may also be secondary to infections, drugs, neoplasms, and autoimmune diseases. We present the case of a 52-year-old Japanese man with coexisting nephrotic MN and immune thrombocytopenic purpura (ITP). Renal biopsy revealed glomerular basement membrane thickening with immunoglobulin (Ig) G and complement component 3 deposition. Glomerular IgG subclass analysis revealed predominant IgG4 deposition with weak IgG1 and IgG2 deposition. IgG3 and phospholipase A2 receptor deposits were negative. Upper endoscopy revealed no ulcers, but histological examination demonstrated Helicobacter pylori infection in the gastric mucosa with elevated IgG antibodies. After gastric Helicobacter pylori eradication, the nephrotic-range proteinuria and thrombocytopenia of the patient were markedly improved without initiation of immunosuppressive treatment. Therefore, clinicians should consider the possibility of Helicobacter pylori infection in patients with coexisting MN and ITP. Further studies are required to demonstrate the associated pathophysiological aspects.