A 40-year-old man is brought to the emergency department because of altered mental status. He appears disoriented and agitated. Per review of the medical record, past medical history is notable for hypertension. He has a 35-year smoking history and consumes 5-7 beers per day. Temperature is 37.2°C (99.0°F), pulse is 100/min, respirations are 25/min, and blood pressure is 148/55 mmHg. On physical examination, the patient is oriented to self but not place or time. His pupils are equal and reactive to light, and fundoscopic examination is unremarkable. Laboratory testing is performed and shown below. Which of the following additional findings will most likely be present in this patient?