Match the following clinical scenarios with their most likely characteristic finding on microscopic urinalysis.
- A 72-year-old man with acute kidney injury following prolonged hypotension from cardiogenic shock.Muddy brown granular casts
- A 28-year-old man with hemoptysis and rapidly declining renal function due to anti-glomerular basement membrane disease.Red blood cell casts
- A 45-year-old woman with new-onset generalized edema, hypoalbuminemia, and 5 grams of proteinuria per day.Fatty casts and oval fat bodies
- A 55-year-old man with acute kidney injury, fever, and a maculopapular rash 10 days after starting cephalexin.White blood cell casts
- A 65-year-old woman with long-standing, poorly controlled hypertension and diabetes mellitus now presenting with an estimated GFR of 12 mL/min.Broad waxy casts
Answer
The correct matches are: Cardiogenic shock (ATN) with muddy brown granular casts; Anti-GBM disease (nephritic syndrome) with red blood cell casts; Nephrotic syndrome with fatty casts; Antibiotic-induced AIN with white blood cell casts; and Advanced CKD with broad waxy casts.
The correct matches accurately pair the specific mechanism of renal injury with its corresponding cast formation in the tubules. Ischemic acute tubular necrosis produces muddy brown granular casts from sloughed necrotic cells. Glomerulonephritis allows RBCs to leak into the filtrate, forming RBC casts. Nephrotic syndrome results in significant lipiduria, visualized as oval fat bodies and fatty casts. Acute interstitial nephritis causes tubular inflammation with WBC casts. Finally, chronic kidney disease involves dilated tubules with sluggish flow, leading to broad waxy casts.
Step-by-Step Solution
Key Concept
Urinary sediment patterns and corresponding etiologies