(C) A statin drug.
This man is suffering from acute tubular necrosis (ATN), which is shown by the granular casts in his urine. A documented adverse effect of statin drugs is that they can cause rhabdomyolysis, or the destruction of skeletal muscle with subsequent excretion of myoglobin by the kidneys. Myoglobin is nephrotoxic and, in significant amounts, may lead to ATN (also a common complication of crush injuries). There is no hemoglobin in the urine; myoglobin is causing the urine to turn red.
Answer A is incorrect. β-Blockers do not cause ATN. The adverse effects commonly seen with β-blockers include impotence, exacerbation of asthma, bradycardia, atrioventricular block, and sedation. In patients with diabetes, there is an increased risk of hypoglycemia both be- cause the drugs inhibit glucose formation and because they mask the signs of symptoms of the hypoglycemic event so that the patient may not realize that his/her sugar is low. Metoprolol can cause a dyslipidemia.
Answer B is incorrect. Hemolytic-uremic syndrome or thrombotic thrombocytopenic purpura could cause acute renal failure, but there is no other evidence of this type of process.
Answer D is incorrect. A crush injury could cause this scenario, but any injury large enough to cause kidney failure would certainly be noticeable to the patient and/or doctors.