A 55-year-old woman comes to the physician for an annual physical examination. She has no new complaints, except fatigue. She has an 8-year history of chronic low back pain; severe degenerative joint disease has been documented on MRI. She had an anterior wall myocardial infarction four years ago. Her current medications include naproxen, acetaminophen, oxycodone, aspirin, atenolol, and simvastatin. Her blood pressure is 130/80 mm Hg and pulse is 72/min. Laboratory studies show: Serum protein electrophoresis is negative for monoclonal gammopathy. Two years ago, her BUN level was 22 mg/dL, and creatinine level was 1.6 mg/dL. Which of the following is the most likely pathology involved in this patient's renal failure?

Question

A 55-year-old woman comes to the physician for an annual physical examination.  She has no new complaints, except fatigue.  She has an 8-year history of chronic low back pain; severe degenerative joint disease has been documented on MRI.  She had an anterior wall myocardial infarction four years ago.  Her current medications include naproxen, acetaminophen, oxycodone, aspirin, atenolol, and simvastatin.  Her blood pressure is 130/80 mm Hg and pulse is 72/min.  Laboratory studies show:  Serum protein electrophoresis is negative for monoclonal gammopathy.  Two years ago, her BUN level was 22 mg/dL, and creatinine level was 1.6 mg/dL.  Which of the following is the most likely pathology involved in this patient's renal failure?

Quizplus · Accepted Answer

Analgesic nephropathy is the most common form of drug-induced chronic renal failure. It accounts for 3-5% of end stage renal disease in the USA, and is most commonly seen in females (peak at age 50-55 years) who habitually use combined analgesics (eg, aspirin and naproxen). It is generally seen after cumulative ingestion of 2-3 kg (4.4-6.6 lbs) of the index drug. Papillary necrosis and chronic tubulointerstitial nephritis are the most common pathologies seen. Polyuria and sterile pyuria (WBC casts may also be seen) are early manifestations. Microscopic hematuria and renal colic may occur following sloughing of renal papilla. Hypertension, mild proteinuria, and impaired urinary concentration commonly occur as the disease advances. In severe cases, nephrotic range proteinuria can be seen. Patients with chronic analgesic abuse are also more likely to develop premature aging, atherosclerotic vascular disease, and urinary tract cancer. (Choice A) Acute tubular necrosis causes acute kidney injury, rather than insidious progression of renal dysfunction. It is most commonly seen in ischemic or nephrotoxic acute renal failure. Muddy brown granular casts are characteristic. (Choice B) Glomerulonephritis manifests as nephritic syndrome. Hematuria (RBC casts), edema, hypertension, and proteinuria are characteristic. (Choice D) Chronic pyelonephritis can cause chronic tubulointerstitial nephritis; however, it is associated with a history of recurrent urinary tract infections and symptoms such as fever, back pain, and dysuria. Educational objective: Analgesic nephropathy is the most common form of drug-induced chronic renal failure. Papillary necrosis and chronic tubulointerstitial nephritis are the most common pathologies seen. Patients with chronic analgesic abuse are also more likely to develop premature aging, atherosclerotic vascular disease, and urinary tract cancer.

A 55-Year-Old Woman Comes to the Physician for an Annual