A 63-year-old man comes to the office due to fatigue. Medical history includes hypertension, for which he takes lisinopril, and osteoarthritis of the right knee, for which he has taken naproxen daily for the past 3 months. Blood pressure is 123/78 mm Hg, and pulse is 78/min. Examination shows that the right knee is mildly deformed due to bony overgrowth; there is no focal tenderness or edema.
Laboratory results are as follows:
Hemoglobin9 g/dL
Mean corpuscular volume72 µm3
Platelets300,000/mm3
Leukocytes7,200/mm3
Creatinine1.2 mg/dL
Which of the following laboratory findings is most likely present in this patient?