American Board of Internal Medicine (ABIM) Certification Practice Exam

In anti-GBM antibody disease, what does electron microscopy typically reveal?

1. Electron-dense deposits

2. No notable findings

3. Normal glomerular structure

4. Hypertrophy of glomerular cells

The correct answer is: No notable findings

In anti-GBM (glomerular basement membrane) antibody disease, electron microscopy typically reveals no notable findings in the glomerular structure. This is a hallmark of this condition as the disease primarily involves the formation of antibodies against the glomerular basement membrane, leading to linear deposits of IgG along the basement membrane. Unlike other renal diseases where electron microscopy might show distinct changes such as electron-dense deposits or hypertrophy of cells, the glomeruli in anti-GBM antibody disease often appear relatively normal under electron microscopy. This absence of findings is due to the specific pathophysiological process that targets the glomerular basement membrane rather than causing structural changes visible under the microscope. Thus, the typical result of "no notable findings" reflects the nature of how this disease manifests at the microscopic level.