Diagnostic and Prognostic Use of PLA2R and THSD7A in Membranous Nephropathy

Diagnostic Applications

A positive anti-PLA2R antibody test in a patient with nephrotic syndrome is sufficient to diagnose primary membranous nephropathy without requiring kidney biopsy, according to the American College of Physicians 1
The American Journal of Kidney Diseases recommends ordering anti-PLA2R antibody testing in all patients presenting with nephrotic syndrome as part of the initial workup 1
Anti-PLA2R antibodies are positive in approximately 70-80% of primary MN cases, with 94% specificity, as reported by the American College of Physicians 1
High titer anti-PLA2R (>20 RU/mL) has 91% positive predictive value for primary MN and allows proceeding without biopsy in appropriate clinical context, according to the American College of Physicians 1
The American Journal of Kidney Diseases suggests confirming diagnosis with two additional assays if relying solely on serology to guide treatment decisions 2

High anti-PLA2R antibody titers at diagnosis predict lower rates of spontaneous remission and longer duration of proteinuria, as reported by the American Journal of Kidney Diseases 2
The American Journal of Kidney Diseases states that spontaneous remission rates are inversely related to antibody levels at diagnosis 2
Longitudinal monitoring of anti-PLA2R antibody levels at 6 months after starting therapy is critical for evaluating treatment response and guiding adjustments, according to the American Journal of Kidney Diseases 4
Changes in antibody levels precede and predict changes in proteinuria by 6 or more months, as reported by the American Journal of Kidney Diseases 2
Disappearance of anti-PLA2R antibodies by 6 months indicates successful immunologic remission and should prompt limiting further immunosuppression, according to the American Journal of Kidney Diseases 4

The American Journal of Kidney Diseases recommends proteinuria <3.5 g/day, serum albumin >30 g/L, and eGFR >60 mL/min/1.73m² as criteria for not requiring immunosuppression 4
Increasing proteinuria or rising anti-PLA2R antibody titers over time changes the risk estimate and may warrant treatment, as reported by the American Journal of Kidney Diseases 4

The American Journal of Kidney Diseases warns not to assume positive anti-PLA2R antibodies exclude secondary causes—evaluate for malignancy, lupus, hepatitis, and medications regardless of antibody status 2
The American College of Physicians advises not to use THSD7A or NELL1 antibodies alone without biopsy—these lack the diagnostic accuracy of PLA2R testing 1
The American Journal of Kidney Diseases suggests not to interpret antibody levels at a single time point for treatment decisions 4
The American College of Physicians recommends not to delay biopsy when kidney function is rapidly declining—this suggests alternative pathology requiring histologic evaluation 1