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Difficulty: EasyNephrology

A fundamental aspect of diagnosing renal pathology involves interpreting urine microscopy. Match each of the following clinical renal conditions with its characteristic, classic urinalysis sediment finding.

  • Acute tubular necrosis (ATN)Muddy brown granular casts
  • Acute interstitial nephritis (AIN)White blood cell (WBC) casts and eosinophiluria
  • GlomerulonephritisRed blood cell (RBC) casts and dysmorphic RBCs
  • End-stage renal disease (ESRD)Broad waxy casts

Answer

Acute tubular necrosis pairs with muddy brown granular casts. Acute interstitial nephritis pairs with WBC casts and eosinophiluria. Glomerulonephritis pairs with RBC casts and dysmorphic RBCs. End-stage renal disease pairs with broad waxy casts.
Each urinalysis finding is directly linked to the underlying pathophysiology of the specific renal disease, serving as a highly specific diagnostic marker for that condition.

Step-by-Step Solution

1
Analyze the pathophysiology of Acute tubular necrosis (ATN)
Identified as necrosis of tubular cells
Necrotic cells form muddy brown granular casts in the tubular lumen.
2
Analyze the pathophysiology of Acute interstitial nephritis (AIN)
Identified as an inflammatory/allergic reaction
Inflammation introduces white blood cells and eosinophils into the urine, forming WBC casts.
3
Analyze the pathophysiology of Glomerulonephritis
Identified as glomerular barrier breakdown
Disrupted glomeruli allow RBCs to leak through, becoming dysmorphic and trapping in casts.
4
Analyze the pathophysiology of End-stage renal disease (ESRD)
Identified as chronic structural changes with dilated tubules
Stasis in enlarged tubules allows for the formation of large, broad waxy casts.

Key Concept

Urine microscopy provides crucial diagnostic clues for localizing the exact site of renal injury (e.g., glomerulus, tubules, or interstitium).
Estimated Time:45s
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Topics

Nephrology

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