Polycythemia vera (NORD)

 A 62-year-old man comes to his primary care physician for evaluation of daily headaches and blurry vision. These symptoms started two months ago. In addition, the patient reports feeling itchy over his body after bathing or visiting the sauna. Past medical history is notable for hypertension and asymptomatic gallstones were discovered on a recent ultrasound. The patient is a former smoker with a 20-pack-year smoking history. On the physical exam, the patient is observed to have facial plethora and a spleen palpated 2 cm below the left costal margin. Laboratory testing is ordered and the results are as follows:  

Laboratory Results
Hemoglobin  18.1 g/dL  
Hematocrit  54%  
Erythrocytes  7.2 million/mm3  
Leukocytes  12,500/mm3  
Platelets  470,000/mm3  
Uric Acid  7.9 mg/dL  

Which of the following best describes the pathophysiology of this patient’s presentation?