Polycythemia is best described as what?

• A. A blood disorder occurring when there are too many red blood cells, which carry oxygen from the lungs through the blood stream to the rest of the body.
• B. A condition with low red blood cell count.
• C. A disorder of white blood cells.
• D. A problem with plasma proteins.

Answer: (A)

Polycythemia means there are too many red blood cells, increasing the total red cell mass. Red blood cells are responsible for carrying oxygen from the lungs to the tissues, so having too many of them makes the blood thicker and more viscous. This higher viscosity can slow blood flow and raise the risk of clotting, which is a key reason why polycythemia is a significant condition. The other options describe issues that are not about an excess of red blood cells: a low red blood cell count is anemia, a white blood cell disorder involves white cells, and a plasma protein problem involves components in the plasma rather than red blood cell mass.