Q. A 58-year-old man presents to the clinic complaining of generalized body aches, fever, and decreased urine output for the past two weeks. He reports that he has been taking a course of antibiotics for a urinary tract infection prescribed by his primary care physician. On examination, the patient is found to have bilateral flank tenderness. His laboratory investigations reveal a serum creatinine of 3.5 mg/dL and a blood urea nitrogen of 50 mg/dL. Urinalysis showed white blood cells > 20/HPF, red blood cells 2-5/HPF, and granular casts. His urine cultures are negative. A diagnosis of acute interstitial nephritis is suspected. What is the next best step in management?