What does hematocrit percentage reflect?

• A. The total number of red blood cells in the body
• B. The concentration of hemoglobin in blood
• C. The proportion of red blood cells in blood
• D. The amount of plasma in blood

Answer: (C)

Hematocrit percentage shows the proportion of red blood cells in the blood. It’s a volume fraction—how much of the blood’s total volume is made up by red blood cells. This value is typically measured by spinning a blood sample and comparing the red cell layer to the entire sample, giving a percentage.

Because it reflects a part of the whole blood, hematocrit can change with hydration or certain conditions: it rises with dehydration or polycythemia (more red cells relative to plasma) and falls with anemia or overhydration (less red cells relative to plasma). It does not measure the total number of red blood cells, nor the concentration of hemoglobin, nor the amount of plasma itself.