A secondary polycythemia in which there is an appropriate increase of erythropoietin is referred to as physiologic polycythemia. This form of polycythemia is a normal adaptation in individuals living at high altitudes. Some athletes take the advantage of training at high altitude to improve and develop greater stamina.
Smoking, renal or liver tumors, and tissue hypoxia can also cause secondary polycythemia.
See also: primary polycythemia