Which condition is defined by a low hematocrit or reduced Hb content of RBCs?

• A. Polycythemia
• B. Anemia
• C. Leukopenia
• D. Thrombocytopenia

Answer: (B)

Anemia is defined by a reduced oxygen-carrying capacity of the blood, shown by a low hematocrit or a decreased hemoglobin content in red blood cells. Hematocrit is the percentage of blood volume made up by RBCs, and hemoglobin is the oxygen-cinding protein inside those cells. When RBC mass or the Hb concentration drops, the blood carries less oxygen to tissues, causing symptoms like fatigue and pallor. The other conditions describe problems with different blood components: too many RBCs (polycythemia) would raise hematocrit, while low white blood cells or low platelets refer to leukopenia and thrombocytopenia, respectively.