USMLE Answer 16

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16. The correct answer is A. The two principal causes of rapidly progressive glomerulonephritis are anti-glomerular basement membrane (including both Goodpasture syndrome and isolated anti-glomerular basement disease) and primary systemic vasculitis (including Wegener granulomatosis, microscopic polyarteritis, idiopathic rapidly progressive glomerulonephritis, Churg-Strauss syndrome, polyarteritis nodosa, giant-cell arteritis, and Takayasu arteritis). A very large variety of other systemic and primary glomerular disease may occasionally cause rapidly progressive glomerulonephritis, but this is usually not the typical presentation for these diseases.

Diabetic nephropathy (choice B) typically begins with microalbuminuria and hypertension and progresses over a 10- to 20-year period to renal failure.

Hypertensive nephropathy (choice C) due to essential hypertension typically presents with slowly rising BUN and creatinine; hypertensive nephropathy due to malignant hypertension presents with more rapidly rising BUN and creatinine.

Lupus nephritis (choice D) can have many presentations, but the most typical is proteinuria, which may be severe enough to cause nephrotic syndrome. Also, 90% of cases of systemic lupus erythematosus occur in women, usually of child-bearing age.

Minimal change disease (choice E) typically presents with nephrotic syndrome and is not consistently associated with recognizable glomerular changes by light microscopy. Podocyte foot-process fusion can be seen by electron microscopy.