Etiology and clinical characteristics of membranous nephropathy in Chinese patients.

BACKGROUND

Membranous nephropathy (MN) is a common cause of proteinuria and can be subdivided into idiopathic and secondary classifications. Most patients with MN present with associated systemic diseases that need to be identified before appropriately diagnosing idiopathic MN. However, the cause and clinical characteristics of MN in Chinese patients have not been investigated.

STUDY DESIGN

Case series.

SETTING & PARTICIPANTS: Patients with biopsy-proven MN at the Research Institute of Nephrology, Jinling Hospital, Nanjing University School of Medicine, Nanjing, China.

OUTCOME

The diagnosis of idiopathic and secondary MN was based on clinical, initial laboratory, and histological findings.

RESULTS

390 patients with MN were identified from 1985 to 2005. Of 390 patients with MN, 124 (31.8%) had idiopathic MN and 266 had secondary MN (68.2%). Of patients with idiopathic MN, 75 (60.5%) were men and 49 (39.5%) were women. Mean age was 43.9 +/- 13.2 years (range, 14 to 78 years). Common presentations of idiopathic MN were 60.5% with proteinuria (39.5% of whom presented with nephrotic syndrome), 29.8% with hypertension, 17.7% with hematuria, and 0.8% with decreased kidney function. In patients with secondary MN, causes were autoimmune diseases (73.3%), infections (17.7%), tumors (4.5%), and drugs or toxins (4.5%). Systemic lupus erythematosus was the most common autoimmune disease (predominately in younger women). Hepatitis B predominated in younger men. Greater levels of proteinuria were found in patients who presented with drugs or toxins compared with patients with other secondary MNs (P < 0.05).

LIMITATIONS

Not all patients underwent all tests, particularly serum tumor markers, hepatitis C virus antibody, and hepatitis C virus RNA tests.

CONCLUSION

Proteinuria was a common presentation in patients with idiopathic MN, which was predominately found in middle-aged to elderly men. Secondary MN was more common than idiopathic MN, and most secondary MN diagnoses were secondary to systemic lupus erythematosus and hepatitis B infection.