Etiological differentiation optimizes diagnosis
Distinguishing primary from secondary membranous nephropathy
One of the main causes of nephrotic syndrome in adults, membranous nephropathy (MN), is most often autoimmune in nature due to autoantibodies against the phospholipase A2 receptor (PLA2R). These cases are referred to as primary MN. The remainder of cases are referred to as secondary MN and are associated with other autoantibodies related to other diseases or exposures. The natural course of MN varies and cannot be predicted, resulting in ongoing challenges for disease management.
A distinct classification
Membranous nephropathy occurs as a result of the accumulation of immune complexes, or antigen-antibody complexes, along the subepithelial region of the glomerular basement membrane. Until recently, researchers and clinicians described primary MN as idiopathic; however, the discovery of two target antigens for immune complexes, PLA2R in 2009, and THSD7A in 2014, established MN as a kidney-specific autoimmune disease.
The presence of PLA2R and THSD7A accounts for approximately 70% of primary MN cases. In 2019, Mayo Clinic researchers identified another antigen-antibody complex, identified as neural epidermal growth factor-like 1 (NELL-1), as the second most common antigen associated with primary MN. Classification of MN disease subtypes is critical to ensure accurate diagnosis and intervention.
By the numbers
of patients with primary MN are positive for PLA2R
of patients with primary MN are positive for NELL-1
of patients with primary MN are positive for THSD7A
Your partner for accuracy
Extensive clinical, laboratory, and pathologic evaluation to accurately identify the underlying etiology is required to distinguish primary MN from secondary MN.1 Mayo Clinic Laboratories offers comprehensive renal testing services, concise results, and access to more than 150 years of advanced medical knowledge to deliver the answers your practice needs to increase accuracy, improve outcomes, and keep care local.
A Test in Focus
John Lieske, M.D., gives an overview of the phospholipase A2 receptor antibodies testing available through Mayo Clinic Laboratories. He discusses when this testing should be ordered, how this testing improves upon previous testing approaches, and what clinical action can be taken due to the results of this testing.
Identify the antigen
Anti-phospholipase A2 receptor (PLA2R) antibodies are highly specific for the diagnosis of primary MN. A titer increase, decrease, or disappearance generally precedes a change in clinical status.
Confirm the causation
Comprehensive, clinically validated testing elevates primary MN diagnosis. Mayo Clinic Laboratories offers a full menu of assays to assess renal pathologies.
*Note: RPCWT automatically performs IF staining for PLA2R if MN is present (based on LM and IF). If PLA2R IF is negative, IF staining for THSD7A and IHC staining for NELL-1 will be performed.
NELL1 | Neural Epidermal Growth Factor-Like 1 Protein Immunostain, Technical Component Only (Temporarily unavailable)
A Test in Focus
Sanjeev Sethi, M.D., Ph.D., discusses how Mayo Clinic Laboratories’ new immunohistochemistry test for the detection of NELL-1 antigen, a biomarker for membranous nephropathy found in 10% to 15% of all MN patients, provides diagnostic certainty and insight on disease expression.
Learn more about how to order this evaluation at your institution.