Increased levels of which blood component are typically associated with polycythemia?

In the context of polycythemia, the condition is characterized by an increase in the number of red blood cells (RBCs) in the bloodstream. This increase can lead to greater blood viscosity, which may result in various complications, such as hypertension and thrombosis.

Polycythemia can be classified into primary and secondary forms. Primary polycythemia (Polycythemia Vera) is a myeloproliferative disorder where there is an intrinsic problem with the bone marrow leading to overproduction of red blood cells. Secondary polycythemia, on the other hand, occurs due to external factors such as chronic hypoxia or tumors producing erythropoietin, which stimulate the bone marrow to produce more RBCs.

Considering the choices provided, increased levels of red blood cells are the hallmark of polycythemia, making them the correct answer. The other blood components listed, such as white blood cells, platelets, and plasma proteins, do not directly correlate with the primary characteristic of polycythemia, which focuses on the elevation of red blood cells specifically. While these components may be affected in various conditions, they are not the defining factors of polycythemia itself.