Which parameter most directly indicates the blood's oxygen-carrying capacity?

Which parameter most directly indicates the blood's oxygen-carrying capacity?

• A. Hematocrit
• B. Hemoglobin
• C. Platelet count
• D. White blood cell count

Answer: (B)

Oxygen-carrying capacity is determined by how much hemoglobin is available to bind oxygen. Hemoglobin is the protein inside red blood cells that picks up O2 in the lungs and releases it to tissues. The amount of hemoglobin in the blood (measured as grams per deciliter) directly sets how much oxygen can be carried. Hematocrit—the proportion of blood that is red blood cells—roughly reflects red cell mass but does not directly quantify the hemoglobin content. Platelet and white blood cell counts relate to clotting and immune function, not oxygen transport.

Oxygen-carrying capacity is determined by how much hemoglobin is available to bind oxygen. Hemoglobin is the protein inside red blood cells that picks up O2 in the lungs and releases it to tissues. The amount of hemoglobin in the blood (measured as grams per deciliter) directly sets how much oxygen can be carried. Hematocrit—the proportion of blood that is red blood cells—roughly reflects red cell mass but does not directly quantify the hemoglobin content. Platelet and white blood cell counts relate to clotting and immune function, not oxygen transport.