Clinical Challenge: Left Flank Pain

History of Present Illness

A 62-year-old man presents to the emergency department with left flank pain that has been present for 1 week. The patient has had no fever, vomiting, hematuria, or abdominal pain but states he seems to be urinating less frequently than normal and has felt a bit nauseous and fatigued.

Vital Signs and Physical Examination

The patient’s vital signs appear normal, with the exception of elevated blood pressure at 160/100 mmHg. The physical examination reveals no significant abnormalities, except for mild bilateral tenderness in the flank and lower abdominal areas, without any signs of rebound tenderness or guarding.

Initial diagnostic tests show a normal complete blood count and chem 7, with the exception of a bicarbonate level of 18 mEq/L, creatinine level of 18.5 mg/dL, BUN of 100 mg/dL, and potassium at 6.0 mEq/dL. Urine analysis reveals a red blood cell count of 140 per high power field (hpf) and a white blood cell count of 10/hpf.

In response to these findings, the physician has ordered a computed tomography urogram. (Figure)