Which of the following is the earliest structural change demonstrable in the kidneys of a patient with diabetes mellitus?
- A Diffuse thickening of the glomerular basement membrane on electron microscopy ✓
- B Kimmelstiel-Wilson nodules on light microscopy
- C Arteriolar hyaline arteriolosclerosis visible on light microscopy
- D Global glomerulosclerosis with tubular atrophy
Correct answer: A. Diffuse thickening of the glomerular basement membrane on electron microscopy
Explanation
GBM thickening detectable by electron microscopy precedes overt albuminuria and is the earliest morphologic change in diabetic nephropathy, accompanied by mesangial matrix expansion. Kimmelstiel-Wilson nodules and hyaline arteriolosclerosis appear later, once macroalbuminuria and declining function are established. Global glomerulosclerosis represents end stage scarring. This sequence explains why normoalbuminuric diabetics may still show ultrastructural basement membrane changes on biopsy.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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