Approach to the patient with rapidly progressive glomerulonephritis

Mr. A, a 68-year-old male with no history of renal disease, was evaluated for upper respiratory symptoms including cough and postnasal drip. A 10-day course of amoxicillin was prescribed for presumed sinusitis. After 2 weeks, his symptoms did not improve, and levofloxacin was started. One month after the initial presentation, he presented to the emergency department with progressive dyspnea, abdominal pain, and nausea. Serum creatinine level is 7.1 mg/dL (1 month ago, serum creatinine was 1.0 mg/dL), and he is admitted to the hospital for urgent evaluation. On exam, he is afebrile, and blood pressure is 162/90 mmHg. Scattered bilateral pulmonary crackles were noted on exam, and chest X-ray revealed bilateral nodular pulmonary infiltrates. Urinalysis showed 3+ protein with renal epithelial cells, granular casts, 50 red blood cells (RBCs) per high power field (HPF) with many dysmorphic RBCs, and RBC casts on microscopy.