Membranous nephropathy assay: PMND1


Test in Focus

Primary membranous nephropathy is a kidney disease that can ultimately lead to kidney failure. In this "Test in Focus" episode of the "Answers From the Lab" podcast, John Lieske, M.D., describes Mayo Clinic Laboratories' new test for antigens that cause membranous nephropathy. PMND1 is a diagnostic cascade that will replace the laboratory's current PLA2R test.

"Diagnostic testing for membranous nephropathy has evolved a lot over the last 10 years," Dr. Lieske says. "In addition to PLA2R, other membranous nephropathy antibodies are being reported."

PMND1 uses ELISA and IFA testing to check for the PLA2R antigen, the most common cause of membranous nephropathy. If test results are negative for PLA2R, the diagnostic cascade uses IFA to test for THSD7, another cause of membranous nephropathy.

"In the future we would add other antigens to the cascade as tests become available," Dr. Lieske says."This diagnostic cascade is the most logical and cost-effective way to make the initial diagnosis of which antigen is causing membranous nephropathy."

Kidney biopsy has been the gold standard of diagnostic testing for membranous nephropathy. However, recently updated KDIGO guidelines suggest that PLA2R testing may be used as an alternative.

Dr. Lieske notes that kidney biopsy remains the gold standard for patients with nephrotic syndrome. But ELISA and IFA tests are 60% to 70% sensitive and nearly 100% specific for PLA2R.

"For patients with preserved kidney function who are considered at relatively low risk for progression, PLA2R testing is a very reasonable approach," he says. "It's important to point out that a subset of patients with membranous nephropathy will have secondary contributing causes and should also be screened for them."

Mayo Clinic Laboratories will offer an additional test for monitoring patients with PLA2R-positive membranous nephropathy. The PLA2M test will use ELISA to measure PLA2R titer, which can inform physicians about response to treatment as well as relapse or remission.

"PLA2R titer testing is very helpful for monitoring patients on treatment," Dr. Lieske says. "A physician who already knows a patient has PLA2R-positive membranous nephropathy can go straight to ordering that PLA2M test."

Listen to learn more about how the PMND1 test provides efficient and cost-effective diagnosis of membranous nephropathy.

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Testing

Useful information

PMND1   | Primary Membranous Nephropathy Diagnostic Cascade, Serum

  • Distinguishing primary from secondary membranous nephropathy using an algorithmic approach.
  • Monitoring patients with membranous nephropathy at very low antibody titers.
  • Screening for anti-phospholipase A2 receptor antibodies.

PLA2M   | Phospholipase A2 Receptor, Enzyme-Linked Immunosorbent Assay, Serum

  • Distinguishing primary from secondary membranous nephropathy.
  • Monitoring patients with membranous nephropathy, over time, for trends in anti-phospholipase A2 receptor antibody levels.

PLA2I   | Phospholipase A2 Receptor, Immunofluorescence, Serum

  • Distinguishing primary from secondary membranous nephropathy in patients with low levels of anti-phospholipase A2 receptor (PLA2R) antibodies.
  • Screening for anti-PLA2R antibodies.
  • Monitoring patients with membranous nephropathy at very low antibody titers.

THSD7   | Thrombospondin Type-1 Domain-Containing 7A Antibodies, Serum

  • Confirm disease subtype in a patient with biopsy-proven MN who is PLA2R-negative.
  • Monitoring disease progression in patients with confirmed THSD7-associated PMN.
  • Guiding immunosuppressive therapy in patients with confirmed THSD7-associated PMN.

Specimen requirements

PMND1   | Primary Membranous Nephropathy Diagnostic Cascade, Serum

Specimen Type: Serum

Supplies: Aliquot Tube, 5 mL (T465)

Acceptable: Red top

Preferred: Serum gel

Specimen Volume: 1 mL

Collection Instructions: Centrifuge and aliquot serum into plastic vial within 2 hours of collection.

PLA2M   | Phospholipase A2 Receptor, Enzyme-Linked Immunosorbent Assay, Serum

Specimen Type: Serum

Supplies: Aliquot Tube, 5 mL (T465)

Acceptable: Red top

Preferred: Serum gel

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions: Centrifuge and aliquot serum into plastic vial.

PLA2  | Phospholipase A2 Receptor, Immunofluorescence, Serum

Specimen Type: Serum

Supplies: Aliquot Tube, 5 mL (T465)

Acceptable: Red top

Preferred: Serum gel

Specimen Volume: 1 mL

Collection Instructions: Centrifuge and aliquot serum into plastic vial within 2 hours of collection.

THSD7   | Thrombospondin Type-1 Domain-Containing 7A Antibodies, Serum

Specimen Type: Serum

Supplies: Aliquot Tube, 5 mL (T914)

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions: Centrifuge and aliquot serum into plastic vial within 2 hours of collection.

Performance information

PMND1   | Primary Membranous Nephropathy Diagnostic Cascade, Serum

PLA2I   | Phospholipase A2 Receptor, Immunofluorescence, Serum

  • Analytic time: 3 days
  • Day(s) and time(s) performed: Monday, Wednesday, Friday 7 a.m.- 4 p.m.
  • Specimen Retention Time: 7 Days

PLA2M   | Phospholipase A2 Receptor, Enzyme-Linked Immunosorbent Assay, Serum

  • Analytic time: 3 days
  • Day(s) and time(s) performed: Monday through Friday 8 a.m.
  • Specimen Retention Time: 7 Days

THSD7   | Thrombospondin Type-1 Domain-Containing 7A Antibodies, Serum

  • Analytic time: 3 - 7 days
  • Day performed: Tuesday
  • Specimen Retention Time: 7 Days

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Barbara J. Toman (@barbaratoman)

Barbara J. Toman

Barbara J. Toman is a Senior Communications Specialist at Mayo Clinic Laboratories. She is also the science writer for Mayo’s Neurosciences Update newsletter, which helps referring physicians to stay informed about Mayo’s treatment and research. Barbara has worked at Mayo Clinic since 2007. She enjoys international travel and cooking.