A 78-year-old woman with poor oral intake for 3 days presents with hypotension (BP 88/52), tachycardia (HR 110), and oliguria. Serum creatinine is 2.8 mg/dL (baseline 0.9), BUN 48 mg/dL, with BUN/Cr ratio of 17:1. Urinalysis shows no proteinuria, casts, or hematuria. She takes no nephrotoxic medications. Which finding most supports prerenal azotemia rather than intrinsic acute tubular necrosis?
- A)Urine sodium greater than 40 mEq/L
- B)BUN to creatinine ratio greater than 20 to 1GABARITO
- C)Loss of medullary concentrating gradient from tubular injury
- D)Fractional excretion of sodium greater than 2 percent
- E)Muddy brown granular casts
Explicação
BUN to creatinine ratio greater than 20 to 1 is correct. In prerenal azotemia the kidneys avidly reabsorb sodium and water in response to hypoperfusion, leading to low urine sodium, low fractional excretion of sodium, concentrated urine, and increased urea rea... Ver explicação completa e trilha adaptativa →