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Difficulty: EasyNephrology

Match the following classic urinalysis sediment findings with their most likely associated renal pathology.

  • Muddy brown granular castsAcute tubular necrosis
  • Red blood cell castsAcute glomerulonephritis
  • White blood cell castsAcute interstitial nephritis
  • Fatty casts (oval fat bodies)Nephrotic syndrome

Answer

Muddy brown granular casts match with Acute tubular necrosis; Red blood cell casts match with Acute glomerulonephritis; White blood cell casts match with Acute interstitial nephritis; Fatty casts match with Nephrotic syndrome.
Urine sediment analysis is a critical, non-invasive diagnostic tool in nephrology. Specific cast types provide direct insight into the underlying pathophysiologic process: necrotic epithelial cells indicate ATN (muddy brown casts), bleeding from glomeruli indicates glomerulonephritis (RBC casts), leukocytic inflammation indicates AIN (WBC casts), and heavy lipiduria indicates nephrotic syndrome (fatty casts).

Step-by-Step Solution

1
Identify the etiology associated with muddy brown granular casts.
Matches with acute tubular necrosis.
Ischemic or nephrotoxic injury causes sloughing of necrotic tubular cells into the lumen, forming these pathognomonic casts.
2
Identify the etiology associated with red blood cell casts.
Matches with acute glomerulonephritis.
Glomerular inflammation disrupts the filtration barrier, allowing red blood cells to enter the tubules and compress into casts.
3
Identify the etiology associated with white blood cell casts.
Matches with acute interstitial nephritis.
Inflammation in the interstitium and tubules (often allergic or drug-induced) leads to leukocyte exudation and cast formation.
4
Identify the etiology associated with fatty casts.
Matches with nephrotic syndrome.
Severe proteinuria triggers hepatic lipoprotein synthesis, leading to hyperlipidemia and subsequent lipiduria, which appears as fatty casts.

Key Concept

Urinalysis interpretation and urine sediment casts in renal disease
Estimated Time:45s
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Topics

Nephrology

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