Major diseases

• The condition indicates an increase in the red blood cell mass which produces hyper viscosity which in turn impairs tissue oxygen delivery and produces vascular occlusion and congestion of capillaries. Vascular occlusion leads to symptoms of peripheral vascular insufficiency, thrombotic and hemorrhagic complications which are: vascular insufficiency leading to ischemic limb pain with or without gangrene. The thrombotic complications are arterial thrombosis and venous thrombosis. Aterial thrombosis in turn leads to angina pectoris, myocardial infarction, pulmonary infarction, cerebral thrombosis and thrombosis of limb artery. Venous thrombosis leads to thrombosis of the hepatic and mesentric vein. There may also be thromboembolic manifestations.
  
  

Hemorrhagic episodes

• Gum bleeding, nose bleeding, presence of blood in the urine, gastro-intestinal bleeding in the form of blood vomiting and melena are commonly experienced by patients.
  
  

Abdominal pain

• Splenic infarction which is the process of tissue death due to insufficient supply of blood, or renal infarction may be the cause of abdominal pain.
  
  

Gouty diathesis

• This is a state of susceptibility to attacks of gout or development of tophi or sodium urate due to raised uric acid level in the blood. Common features include joint pain, joint swelling, renal colicky pain due to urate stone in the kidney and/or ureter and uric acid nephropathy which is an autoimmune disease that affects the kidneys.
  
  

Infection of the respiratory tract

• Inter-current infections especially of the respiratory tract such as bronchitis, which leads to chronic bronchitis and ultimately emphysema, a chronic respiratory disease.
  
  

Enlarged spleen

• Spleen is enlarged chiefly from hyperplasia (proliferation of cells within an organ or tissue) of the pulp and distension with blood in about 75 percent of cases. Splenic infarction is common.
  
  

Other dangers

• With the progression of the disease, proliferation of fibrous element occurs and the disease may pass on to myelofibrosis, a serious bone marrow disorder that disrupts your body's normal production of blood cells. Less commonly, acute myeloid leukemia/chronic myeloid leukemia may occur as terminal event as a result of transformation observed in chronic myeloproliferative disorders.