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Difficulty: MediumNephrology

Match each patient's clinical presentation with the most likely corresponding urinalysis sediment finding.

  • A 62-year-old man who develops acute kidney injury 48 hours after prolonged hypotension during an emergency abdominal aortic aneurysm repair.Muddy brown granular casts
  • A 24-year-old woman with recent onset of a malar rash, photosensitivity, and new hematuria with mild renal insufficiency.Red blood cell casts
  • A 45-year-old man presenting with severe generalized edema, a serum albumin of 2.1 g/dL, and a 24-hour urine protein excretion of 5.2 g.Fatty casts with a 'Maltese cross' appearance
  • A 58-year-old woman presenting with high fever, right-sided costovertebral angle tenderness, dysuria, and acute kidney injury.White blood cell casts
  • A 72-year-old man with longstanding, poorly controlled hypertension and diabetes mellitus, presenting with small, echogenic kidneys on ultrasound.Broad waxy casts

Answer

The correct matches pair acute tubular necrosis with muddy brown casts, glomerulonephritis with red blood cell casts, nephrotic syndrome with fatty casts, acute pyelonephritis with white blood cell casts, and advanced chronic kidney disease with broad waxy casts.
Each clinical vignette presents classic hallmark features for a distinct renal pathology. The underlying mechanism of injury directly dictates the type of cells or substances that precipitate within the renal tubules to form casts: necrotic epithelial cells (ATN), red blood cells (glomerulonephritis), lipids (nephrotic syndrome), neutrophils (pyelonephritis), or degenerate proteins in dilated tubules (advanced CKD).

Step-by-Step Solution

1
Analyze the first patient's presentation involving hypotension and surgery.
Identify ischemia-induced acute tubular necrosis (ATN).
ATN is the most common cause of intrinsic acute kidney injury following severe hypoperfusion.
2
Evaluate the second patient's systemic symptoms and hematuria.
Identify acute glomerulonephritis, likely secondary to systemic lupus erythematosus.
Glomerular inflammation leads to the passage of red blood cells through the damaged basement membrane.
3
Assess the third patient's severe edema, hypoalbuminemia, and massive proteinuria.
Identify nephrotic syndrome.
Proteinuria greater than 3.5 g/day defines nephrotic syndrome, which profoundly alters lipid metabolism.
4
Examine the fourth patient's fever and costovertebral angle tenderness.
Identify acute pyelonephritis.
These are hallmark signs of an upper urinary tract infection involving the renal interstitium.
5
Review the fifth patient's chronic comorbidities and small kidneys on ultrasound.
Identify advanced chronic kidney disease (CKD).
Chronic irreversible scarring leads to loss of renal mass and compensatory hypertrophy of remaining tubules.

Key Concept

Urinalysis sediment and cast differentiation in renal disease
Estimated Time:2m 0s
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Topics

Nephrology

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