Polycythaemia: an increase in the number of erythrocytes and haematocrit

2021-05-07 11:34 PM

Cells do not stop producing red blood cells when they have enough red blood cells. This causes an overproduction of red blood cells as in breast cancer an overproduction of a certain type of breast cell.

Secondary polycythaemia vera

Whenever tissues become hypoxic because of too little oxygen in the breathing air, such as overhead or fail to transport oxygen to tissues such as in heart failure, the hematopoietic organ automatically produces extra-large quantities of red blood cells. This condition is called secondary polycythaemia vera, and the erythrocytes usually increase to 6-7 million / mm3, which is about 30 percent above normal. A common form of secondary polycythaemia vera, called physiologic polycythaemia vera, occurs in indigenous people living at an altitude of 14,000 to 17,000 feet, where oxygen air is very low. The complete blood count is usually between 6 and 7 million / mm3; This blood allows these people to live at constant working altitudes even in a thin atmosphere.

Primary polycythaemia vera (polycythaemia vera, erythraemia)

In addition to physiological polycythaemia, there is a pathological condition called vera polycythaemia vera, in which the number of erythrocytes can reach 7 to 8 million / mm3 and the haematocrit can be 60 to 70 percent instead of the normal 40 -45 percent. Polycythaemia vera is caused by a genetic mismatch in hemocytoblast cells that produce blood cells. Cells do not stop producing red blood cells when they have enough red blood cells. This causes an overproduction of red blood cells as in breast cancer an overproduction of a certain type of breast cell. It often causes excess production of white blood cells and platelets.

In vera polycythaemia vera, not only haematocrit increases, but total blood volume also increases, sometimes almost double normal. As a result, the entire vascular system becomes swollen containing blood. In addition, many blood capillaries become viscous stasis; The viscosity of blood in vera polycythaemia sometimes increases from normal 3 times the viscosity of water to 10 times that of water.



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