A 49-year-old man seeks a prescription for erectile dysfunction. He is 168 cm (5 feet 6 inches) tall and weighs 93 kg (body mass index 33). On physical examination, there are bilateral carotid bruits and a midline palpable abdominal pulsatile mass. Decreased hair is noted over the lower extremities, and a 1-cm shallow ulceration is present in the skin over the right first metatarsal head. He has decreased sensation to light touch and pinprick in the lower extremities. Laboratory findings include hemoglobin, 12.9 g/dL; hematocrit, 42%; WBC count, 8950/ mm3; and creatinine, 1.7 mg/dL. Which of the following laboratory findings is most likely to be present in this man?