Dependant on underlying etiology
May be entirely asymptomatic
Possible features include plethora, tendency towards thromboembolism or bleeding, splenomegaly, pruritus
Polycythemia
Primary polycythemia 
Thrombocytosis
Polycythemia vera
Dyshemoglobinemia
Essential thrombocytosis 
Lactic acidosis
Chronic myelogenous leukemia 