Which of the Following Is a Characteristic Feature of Acute Renal Failure

Mr. Santos, a 60-year-old Male, Is Admitted to the Hospital with Complaints of Decreased Urine Output, Fatigue and Swelling in His Lower Extremities. His Laboratory Results Show Elevated Serum Creatinine and Blood Urea Nitrogen (BUN) Levels. the Physician Suspects Renal Failure and Orders Further Diagnostic Tests