<P> Secondary polycythemia in which the production of erythropoietin increases appropriately is called physiologic polycythemia . </P> <P> Conditions which may result in a physiologically appropriate polycythemia include: </P> <Ul> <Li> Altitude related - This physiologic polycythemia is a normal adaptation to living at high altitudes (see altitude sickness). Many athletes train at high altitude to take advantage of this effect--a legal form of blood doping . Some individuals believe athletes with primary polycythemia may have a competitive advantage due to greater stamina . However, this has yet to be proven due to the multifaceted complications associated with this condition . </Li> <Li> Hypoxic disease - associated - for example in cyanotic heart disease where blood oxygen levels are reduced significantly, may also occur as a result of hypoxic lung disease such as COPD and as a result of chronic obstructive sleep apnea . </Li> <Li> Iatrogenic - Secondary polycythemia can be induced directly by phlebotomy (blood letting) to withdraw some blood, concentrate the erythrocytes, and return them to the body . </Li> <Li> Genetic - Heritable causes of secondary polycythemia also exist and are associated with abnormalities in hemoglobin oxygen release . This includes patients who have a special form of hemoglobin known as Hb Chesapeake, which has a greater inherent affinity for oxygen than normal adult hemoglobin . This reduces oxygen delivery to the kidneys, causing increased erythropoietin production and a resultant polycythemia . Hemoglobin Kempsey also produces a similar clinical picture . These conditions are relatively uncommon . </Li> </Ul> <Li> Altitude related - This physiologic polycythemia is a normal adaptation to living at high altitudes (see altitude sickness). Many athletes train at high altitude to take advantage of this effect--a legal form of blood doping . Some individuals believe athletes with primary polycythemia may have a competitive advantage due to greater stamina . However, this has yet to be proven due to the multifaceted complications associated with this condition . </Li>

In case of polycythemia vera why is blood pressure elevated