All of the following can be expected with polycythemia except .
A increased blood volume.
B low blood viscosity
C high hematocrit.
D high blood pressure.
The correct answer and explanation is:
The correct answer is B. Low blood viscosity.
Polycythemia is a condition characterized by an increase in the number of red blood cells (RBCs) in the bloodstream. This condition leads to a variety of physiological changes in the body, most of which stem from the increased concentration of RBCs. Here’s a breakdown of each option:
A. Increased blood volume: Polycythemia leads to an increase in the number of RBCs, which contributes to an increase in the overall blood volume. This occurs because the RBCs occupy space within the blood vessels, thereby increasing blood mass and volume.
B. Low blood viscosity: This is the incorrect answer. In polycythemia, blood viscosity actually increases, not decreases. The higher concentration of RBCs makes the blood thicker and more viscous. This increased viscosity can lead to slowed blood flow and can strain the heart, as the heart must work harder to pump thicker blood through the vessels.
C. High hematocrit: Hematocrit refers to the proportion of blood volume occupied by RBCs. In polycythemia, this value is elevated because of the higher number of RBCs present in the blood. A high hematocrit is a hallmark of polycythemia.
D. High blood pressure: The increased blood volume and higher blood viscosity can both contribute to elevated blood pressure. Thicker blood moves less easily through blood vessels, which leads to higher resistance and can elevate systemic blood pressure. Additionally, the increased volume of blood can further raise blood pressure.
In summary, polycythemia results in higher blood viscosity, increased hematocrit, and often elevated blood pressure. Low blood viscosity would not be expected in this condition; it would be more likely in cases of anemia or other conditions where there is a decrease in the number of RBCs.