Polycythemia is characterized by?

Polycythemia is a medical condition characterized by an increased concentration of red blood cells in the bloodstream. This increase in red blood cells can lead to higher blood viscosity, which may cause various complications including increased risk of thrombosis. The increased red blood cell count can result from various factors, including chronic hypoxia, bone marrow disorders, or can be a primary condition such as polycythemia vera.

Understanding this terminology is essential as it reflects on the body's production of red blood cells and how it affects overall health. The other choices relate to variations in blood cell counts but do not accurately define polycythemia; specifically, reduced white blood cells and reduced red blood cells don’t characterize this condition, while normal red blood cells would not indicate an abnormal state when discussing polycythemia.