Polycythemia is characterized by increased RBCs, WBCs, and platelets with high hematocrit; what hematocrit value is abnormal?

Polycythemia is characterized by increased RBCs, WBCs, and platelets with high hematocrit; what hematocrit value is abnormal?

• A. Low hematocrit
• B. 66% hematocrit is abnormal
• C. Normal hematocrit
• D. High platelet count only

Answer: (B)

Hematocrit shows the proportion of blood that is made up of red blood cells. In polycythemia, there is an increased red cell mass, so the hematocrit becomes markedly higher than the normal reference range. That elevated value is the clue that the RBC volume is abnormally high. A low hematocrit suggests anemia, a normal hematocrit wouldn’t indicate polycythemia, and platelet count refers to a different component of blood, not the red cells. So the finding consistent with polycythemia is a hematocrit that is significantly above the normal limit.

Hematocrit shows the proportion of blood that is made up of red blood cells. In polycythemia, there is an increased red cell mass, so the hematocrit becomes markedly higher than the normal reference range. That elevated value is the clue that the RBC volume is abnormally high. A low hematocrit suggests anemia, a normal hematocrit wouldn’t indicate polycythemia, and platelet count refers to a different component of blood, not the red cells. So the finding consistent with polycythemia is a hematocrit that is significantly above the normal limit.