This condition may be due to the overproduction of red blood cells or due to a chronically low oxygen levels. For instance, individuals living at high altitudes have relatively higher concentration of RBCs in blood than those who are not. Hence, some athletes train at high altitudes to develop physiologic polycythemia to possess greater stamina.
This condition can also be observed in individuals with emphysema, pulmonary insufficiency and heart failure.
Alternative form: polycythaemia