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Know that Membranous Nephropathy is the most common cause of NS in adults
Name the causes of secondary Membranous Nephropathy
Drugs – penacillamine, gold, captopril
Infection – hepatitis B, syphilis, various parasitic diseases
SLE – careful to check for in young women with Membranous Nephropathy
Malignancy
- Especially in lung, breast, and GI
Important to check for in older patients with Membranous Nephropathy
- Sjogren’s syndrome
- Mixed connective tissue disease
- Systemic metabolic disorders – e.g, diabetes, thyroiditis
- Sickle cell disease
Know the Light Microscopy, Immuno Fluorescense, and Electron Microscopy findings of Membranous Nephropathy
LM
- Glomeruli appear normal early in disease
- Later, diffuse thickening of capillary walls occurs
- Silver stain demonstrates spikes in BM between deposits
- Trichrome stain may reveal deposits themselves
- IF – diffuse, granular pattern of IgG and C3 deposits along subepithelial surface of capillary loops
- EM - Electron dense deposits in subepithelial distribution with effacement of overlying foot processes
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Know the age, clinical manifestations and HLA antigens of patients with Membranous Nephropathy
- Mean age of onset is 40-50
- Most present with nephrotic syndrome (~20% with asymptomatic proteinuria)
- Microscopic hematuria present in ~60%
- RBC casts rare
- HTN is uncommon
- Renal function is usually normal
- IC in blood is RARE – complexes are formed in situ
- Similar to Heymann nephritis in rats linked to HLA locus caused by susceptibility to Ab to a renal auotoantigen
Know how to work up a case of Membranous Nephropathy
Determination of antinuclear and antiDNA Ab, serum complement, rheumatoid factor, cryoglobulin, Hepatitis B Ag, VDRL, and tests to exclude diabetes
Older patients should have a clinical and radiologic search for occult malignancy
Hematuria and flank pain may indicate pulmonary emboli
May have other glomerular disease “ on top of ” Membranous Nephropathy
Know the prognosis of Membranous Nephropathy
Widely variable clinical course
25% -Spontaneous remission
25% have persistent nephrotic range proteinuria for many years while maintaining normal renal function
Remaining 50% show progressive deterioration of renal function that results in end-stage renal disease in about 15 years
No criteria have been identified to predict which course an individual will follow
Category: Pathology Notes
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