Review Question - QID 210739

Foamy urine, edema, and >3.5g of urine protein per day point to nephrotic syndrome, and the microscopic findings suggest membranous nephropathy. Membranous nephropathy can be due to a number of causes including antibodies to the phospholipase A2 receptor.

Membranous nephropathy has the classic clinical findings of nephrotic syndrome. On light microscopy, the disease as seen as glomerular basement membrane thickening. Additionally, there can be serum IgG4 antibodies to phospholipase A2 receptors, which are found in glomerular podocytes. The M-type phospholipase A2 receptor is believed to be the antigen in a majority of idiopathic disease. This leads to immune deposition in the glomerulus and the classic “spike and dome” subepithelial deposits seen on electron microscopy. HBV can be a significant risk factor for membranous nephropathy, along with systemic lupus erythematosus and drugs like NSAIDs and penicillamine.

Incorrect Answers:
Answer 1: Antibodies to the alveolar basement membrane and the glomerular basement membrane are seen in Goodpasture syndrome, which can result in a nephritic syndrome known as rapidly progressive glomerulonephritis.

Answer 3: IgA immune complex deposition is seen in IgA nephropathy (Berger disease), which also presents as a nephritic syndrome. These deposits are found in the mesangial on electron microscopy and immunofluorescent staining.

Answer 4: Loss of podocyte foot processes, or effacement, can be seen on electron microscopy for nephrotic syndromes such as focal segmental glomerulosclerosis and minimal change disease.

Answer 5: An X-linked syndrome associated with glomerular disease is Alport syndrome, which presents as a nephritic syndrome. Alport syndrome involves a mutation in type IV collagen, which does not have to be X-linked.

Bullet Summary:
Membranous nephropathy results in a nephrotic syndrome, and can be associated with IgG4 antibodies to phospholipase A2 receptors.