query: What is the average volume of blood in an adult human?
passage: Blood volume
A typical adult has a blood volume of approximately 5 liters, with females and males having approximately the same blood volume.[1] Blood volume is regulated by the kidneys.
passage: Polycythemia vera
In primary polycythemia, there may be 8 to 9 million and occasionally 11 million erythrocytes per cubic millimeter of blood (a normal range for adults is 4-6), and the hematocrit may be as high as 70 to 80%. In addition, the total blood volume sometimes increases to as much as twice normal. The entire vascular system can become markedly engorged with blood, and circulation times for blood throughout the body can increase up to twice the normal value. The increased numbers of erythrocytes can cause the viscosity of the blood to increase as much as five times normal. Capillaries can become plugged by the very viscous blood, and the flow of blood through the vessels tends to be extremely sluggish.