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A 23-year-old boy is in a fire and sustains burns over 30% of his body. The next day, his serum urea nitrogen (BUN) is 30 mg/dL and his serum creatinine is 0.8 mg/dL. He receives intravenous fluids throughout his course and never has a significant drop in blood pressure or urine output. Which of the following most likely accounts for his BUN and creatinine values?
Options:
A. Decreased renal perfusion
B. Distal urinary tract obstruction
C. Increased synthesis of urea
D. Renal glomerular disease
E. Renal tubule interstitial disease
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B. Distal urinary tract obstruction
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1 bun: creat =30/.8=30 approx..... ARF
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As pt"s blood pressure & urine output did not fall, so this rules out
A. which can lead to ARF.
B. which can result due to myoglobinurea.
I think C. makes more sense ... burn pt. go into catobolic state & negative nitrogen balance leading to inc production of Urea.
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A.
BUN/Creat >20 = pre renal azotemia due to decreased renal perfusion (hypotension)
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hey as BP and UO are nt dropped we r/o A so its cc
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Large amounts of extracellular fluid will be sequestered in the burn area and are lost through the damaged skin, which no longer acts as a barrier to fluid loss. In addition to hypovolemic shock (which is common in these patients), low vascular volume leads to poor kidney perfusion and subsequent renal failure – a common sequence in patients receiving inadequate fluid replacement. In the case of severe electric burns, muscle involvement may result in coagulation necrosis leading to severe myo-globinuria. The myoglobin has a toxic effect on the renal tubules and can cause renal failure. There is also a high incidence of infection with myoglobinuria and major burn due to low body resistance.
A is the answer
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CC.
In burn patients, especially in severe burns, the rate of protein breakdown and amino acid oxidation increases to almost 50% more than in healthy individuals.
That accounts for the elevation in level of urea in this patient.
