[The relationship between anti-phospholipase A2 receptor antibody and idiopathic membranous nephropathy]

To explore the value of anti-phospholipase A2 receptor (PLA2R) antibody in the diagnosis and disease activity monitoring of idiopathic membranous nephropathy (IMN).

A total of 233 patients with IMN proven by kidney biopsy at Peking Union Medical College Hospital from January 2012 to March 2014 were enrolled in this study. Another 46 patients with non-IMN kidney diseases at the same period were selected as control group. Serum titer of anti-PLA2R antibody was measured by quantitative enzyme-linked immuno sorbent assay (ELISA) at the time of renal biopsy. Clinical data were reviewed and retrospectively analyzed. The diagnostic accuracy of anti-PLA2R antibody in IMN was estimated by ROC curve.

The total sensitivity of anti-PLA2R antibody was 60.0% in IMN. However, the sensitivity increased to 71.3% in patients who did not receive immuno-suppression therapies. The specificity of anti-PLA2R antibody was 100.0%, of which was not detected in any of the 25 control patients with lupus nephritis. The area under ROC curve of anti-PLA2R antibody for IMN diagnosis was 0.800. The prevalence of positive anti-PLA2R antibody in nephrotic range proteinuria group and non-nephrotic range proteinuria group were 68.3% and 41.7% (P < 0.05), respectively. The positive rates in patients with serum albumin level less than 30 g/L and more than 30 g/L were 67.3% and 44.6% (P < 0.05), respectively. Hypoalbuminemia became worse (P < 0.05) and the proportion of nephrotic arrange proteinuria rose significantly (P < 0.05) according to the elevation of antibody level.

Anti-PLA2R antibody has high sensitivity and notable specificity for the diagnosis of IMN, which reveals good diagnostic accuracy. The antibody positive rate is affected by immunosuppression therapy, disease activity and other clinical status. Moreover, the antibody could reflect the disease activity.