Membranous nephropathy Flashcards
membranous nephropathy, Rapidly progressive GN
What is the most common cause of primary membranous nephropathy?
Autoantibodies against the phospholipase A2 receptor (PLA2R) on podocytes.
What is the most common cause of nephrotic syndrome worldwide?
membranous nephropathy
Membranous GN is the most common cause for nephrotic syndrome in adults.
What is the role of anti-PLA2R antibody testing in membranous nephropathy?
It confirms the diagnosis of primary membranous nephropathy and can be used to monitor disease activity. Anti-PLA2R antibodies are highly specific for primary membranous nephropathy, confirming the diagnosis and helping distinguish it from secondary causes.
What are common secondary causes of membranous nephropathy?
Infections: Hepatitis B, Hepatitis C, Syphilis
Autoimmune conditions: Systemic lupus erythematosus (class V lupus nephritis), thyroiditis
Drugs: NSAIDs, penicillamine, gold
Malignancies: Solid tumors (lung, breast, colon cancer)
What should be investigated if a biopsy specimen is negative for anti-PLA2R antibodies in membranous nephropathy?
Secondary causes such as malignancy, infection (e.g., hepatitis B or C), autoimmune disease, or drug-related nephropathy should be evaluated.
What malignancies are commonly associated with secondary membranous nephropathy in elderly patients?
Solid tumors such as lung, breast, and colon cancer are commonly linked to secondary membranous nephropathy.
Should preform age-appropriate cancer screens for patients with idiopathic nephropathy.
If anti-PLA2R antibodies are absent, what is the next diagnostic step in elderly patients with membranous nephropathy?
Perform cancer screening, such as colonoscopy, mammography, or CT imaging, to identify secondary causes.
What type of cancer can cause nephropathy but not membranous nephropathy?
Multiple myeloma can cause amyloidosis leading to amyloid nephropathy
Congo red staining, which demonstrates apple-green birefringence under polarized light.
What is the characteristic histological finding in membranous nephropathy on light microscope?
Diffuse capillary and GBM thickening
What is the characteristic histological finding in membranous nephropathy on immunofluorescence?
granular deposition
Membranous nephropathy is an immunologically mediated disease in which deposts of mainly IgG and complement collect in the basement membrane and appear in a diffuse granular pattern
What is the characteristic histological finding in membranous nephropathy on electron microscope?
Subepithelial immune complex deposits seen on electron microscopy, with spike and dome appearance on silver stain.
What special stain is useful in evaluating membranous nephropathy?
Silver stain
There are characteristic “spikes” of basement membrane between the immune deposits of membranous nephropathy. The black basement membrane material shown here appears as projections in the capillary loops.
What is the clinical presentation of membranous nephropathy?
Nephrotic syndrome, including proteinuria >3.5 g/day, hypoalbuminemia, edema, and hyperlipidemia.
Why is testing for C3 complement protein unnecessary in membranous nephropathy?
C3 complement protein testing is relevant for diseases like postinfectious glomerulonephritis or C3 glomerulopathy, which involve low C3 levels. Membranous nephropathy does not typically involve hypocomplementemia.
How is IgA nephropathy differentiated from membranous nephropathy?
IgA nephropathy presents with glomerulonephritis, not nephrotic syndrome, and is associated with anti-IgA antibodies, not anti-PLA2R antibodies.
How can Goodpasture’s syndrome be differentiated from membranous nephropathy?
Goodpasture’s syndrome is associated with anti-glomerular basement membrane (anti-GBM) antibodies, presenting with nephritic syndrome and often pulmonary hemorrhage.
What laboratory findings are common in membranous nephropathy?
Urinalysis: Proteinuria, lipiduria, microscopic hematuria
Serum studies: Hypoalbuminemia, hypercholesterolemia, elevated serum creatinine in advanced disease.
How is secondary membranous nephropathy diagnosed?
By identifying the underlying cause through specific tests such as Hepatitis B/C serologies, ANA testing, or cancer screening.
What is the first-line treatment for primary membranous nephropathy?
Supportive therapy with RAAS blockade (ACE inhibitors/ARBs) for proteinuria and blood pressure control.
Immunosuppressive therapy is used for high-risk cases (e.g., nephrotic-range proteinuria or kidney dysfunction) when the cause is idiopathic.
What immunosuppressive agents are used in membranous nephropathy?
Corticosteroids combined with cyclophosphamide or calcineurin inhibitors
(e.g., tacrolimus or cyclosporine).
What complications are associated with membranous nephropathy?
Thromboembolism (due to hypercoagulability in nephrotic syndrome).
Chronic kidney disease with partial remission common.
Rarely there is a progression to end-stage renal disease (ESRD).
