Relative polycythemia are caused by all of the following, EXCEPT:

High altitude is associated with physiological increase in erythropoietin levels resulting in secondary polycythemia and not relative polycythemia. Polycythemia refers to increase in RBCs, WBCs, and platelets, but in common practice is used to describe increased red cells or erythrocytosis. It can be primary, secondary or relative. In relative polycythemia, the red cell mass is normal, but the plasma volume is decreased resulting in elevated hemoglobin and hematocrit values. Ref: Current Diagnosis and Treatment Emergency Medicine, 7th Edition, Chapter 41; Essentials of Pathophysiology: Concepts of Altered Health States By Carol Mattson Poh Page 293