Diagnostic value of renal biopsy in anti-phospholipase A2 receptor antibody-positive patients with proteinuria in China.

Renal biopsy remains the gold standard for diagnosing membranous nephropathy (MN). Recent studies have suggested that renal biopsy can be replaced with the serum phospholipase A2 receptor (PLA2R) antibody test for MN diagnosis in patients with nephrotic syndrome. However, this test has not been validated in the Chinese population. In this study, we investigated whether renal biopsy provides additional diagnostic information on patients with proteinuria who are seropositive for PLA2R antibodies (SAb +). We retrospectively reviewed the clinicopathological characteristics of SAb + adult patients (aged ≥ 18 years) with proteinuria (≥ 0.5 g/24 h) assessed at the Department of Nephrology, the First Affiliated Hospital of Zhengzhou University, from June 2021 to March 2022. Among a total of 801 SAb + patients who received renal biopsy, those with incomplete pathological data, diabetes or any potential cause of secondary MN were excluded. Among the 491 remaining patients, 474 had primary MN (PMN), 16 had atypical MN (AMN, 9 patients with "full house" and 2 patients with HBsAg + /HBcAg + immunofluorescence results), and 1 had focal segmental glomerulosclerosis. In patients with an eGFR of ≥ 60 mL/min/1.73 m2 (n = 451), 436 had PMN, and 71 (16.3%) exhibited additional biopsy findings, with obesity-related glomerulopathy being the most common. In patients with an impaired eGFR (n = 40), 38 had PMN, and 31 (81.6%) showed additional findings, with acute tubular injury being the most common. In conclusion, anti-PLA2R antibody positivity is highly predictive of PMN in Chinese adults but often coexists with other pathological diagnoses. The advantages of renal biopsy for detecting other pathologies should be weighed against the potential risks of the biopsy procedure.