USMLE Forum Archives - USMLE Step 2 CK - Nephrology question #5
Nephrology question #5
revision - 12-29-08 07:23
A 71-year-old man comes to the emergency department with a 3-day history of malaise and decreased urinary output. He denies any history of flank pain, hematuria, or prior voiding difficulty. There is no fever, nausea, or vomiting, although his appetite is decreased. Past medical history is significant for arthritis that is improved with ibuprofen. Recent illnesses include sinusitis for which he was prescribed amoxicillin. He has been taking the amoxicillin for 3 days and has not noticed any rash or other ill effects from the medication. His temperature is 36.7 C (98.0 F), blood pressure is 158/84 mm Hg, pulse is 98/min, and respirations are 18/min. He seems fatigued but not in distress. His lungs are clear and his heart has a regular rhythm without murmurs. Abdomen is soft, nontender, and without masses. He has no lesions of the penis and rectal examination reveals a smooth, small prostate. Laboratory studies show a BUN of 54 mg/dL, creatinine of 3.5 mg/dL, and potassium of 6 mEq/L. Liver function studies are within normal limits. Urinalysis shows 2+ proteinuria, 11-50 WBC/hpf with casts, and 6-10 RBC/hpf. Urine osmolality is 250 mOsm/L. Which of the following best describes this patient’s condition?
A. Acute tubular necrosis
B. Acute tubulointerstitial nephritis
C. Postrenal acute renal failure
D. Prerenal acute renal failure
E. Unilateral renal obstruction
revision - 12-29-08 07:23
A 71-year-old man comes to the emergency department with a 3-day history of malaise and decreased urinary output. He denies any history of flank pain, hematuria, or prior voiding difficulty. There is no fever, nausea, or vomiting, although his appetite is decreased. Past medical history is significant for arthritis that is improved with ibuprofen. Recent illnesses include sinusitis for which he was prescribed amoxicillin. He has been taking the amoxicillin for 3 days and has not noticed any rash or other ill effects from the medication. His temperature is 36.7 C (98.0 F), blood pressure is 158/84 mm Hg, pulse is 98/min, and respirations are 18/min. He seems fatigued but not in distress. His lungs are clear and his heart has a regular rhythm without murmurs. Abdomen is soft, nontender, and without masses. He has no lesions of the penis and rectal examination reveals a smooth, small prostate. Laboratory studies show a BUN of 54 mg/dL, creatinine of 3.5 mg/dL, and potassium of 6 mEq/L. Liver function studies are within normal limits. Urinalysis shows 2+ proteinuria, 11-50 WBC/hpf with casts, and 6-10 RBC/hpf. Urine osmolality is 250 mOsm/L. Which of the following best describes this patient’s condition?
A. Acute tubular necrosis
B. Acute tubulointerstitial nephritis
C. Postrenal acute renal failure
D. Prerenal acute renal failure
E. Unilateral renal obstruction
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#2
Re: Nephrology question #5
revision - 12-31-08 09:44 Yes the correct answer is B.
This patient is suffering from acute renal failure (ARF) secondary to drug-induced tubulointerstitial nephritis.
ARF denotes an abrupt decline in renal function such that the normal homeostatic mechanisms of the kidney are impaired.
In the broadest sense, ARF can be divided into prerenal, renal (intrinsic), and postrenal causes.
Intrinsic renal failure is most commonly caused by acute tubular necrosis (ATN) or acute interstitial nephritis (AIN).
AIN is characterized by a decreased glomerular filtration rate (GFR) and is usually associated with some degree of proteinuria and active urinary sediment. Eosinophiluria may be present.
Tubular dysfunction is the rule and may manifest as various electrolyte disturbances and concentrating defects.
AIN is categorized as drug-related, infection-related, or idiopathic.
Offending agents include semisynthetic penicillins, sulfa drugs, NSAIDs, and H-2 blockers.
Treatment of AIN is directed at supportive care and correction of electrolyte abnormalities.
The offending agent should be withdrawn.
#6
Re: Nephrology question #5 babbu5508 - 08-29-10 01:39 B. Acute tubulointerstitial nephritis due to drugs...shown by acute renal failure proteinuria, rbc and wbc in urine with elevated bun
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