A 72-year-old man with congestive cardiomyopathy undergoes transurethral resection of the prostate. Three days following the procedure, he develops a fever of 103 F and a new-onset 2/6 holosystolic murmur auscultated best at the apex. He is admitted to hospital and treated empirically with vancomycin and gentamicin. Laboratory studies taken 24 hours after admission are shown:
Serum blood urea nitrogen: 35 mg/dL
Serum creatinine: 2.0 mg/dL
Fractional excretion of sodium (FeNa): <1%
Which of the following is the most likely cause of this patient’s laboratory findings?
Acute interstitial nephritis
Acute tubular necrosis
Congestive cardiomyopathy
Emboli
History of benign prostatic hyperplasia
