What are hemoglobin and hematocrit?
Hemoglobin (Hb) is the protein in red blood cells which contains heme. It transports oxygen from the lungs to other body tissues and also transports carbon dioxide in the reverse direction. About 98 percent of the protein in red blood cells is hemoglobin. In normal adults, 97 percent of the total hemoglobin is HbA which has two α subunits or globin chains and two β subunits (α2β2).Other possible globin subunits are γ and δ. In the fetus, the Hb is α2γ2. During the last three months of pregnancy, γ-chain synthesis switches to β-chain synthesis. In certain congenital anemias, the production of γ chains persists. The hematocrit (Hct) is a measure of what percentage of the blood is composed of red blood cells. Usually a low level of iron in the body causes too few red cells to be formed and this causes a low hematocrit. There are other causes of a low Hct (and Hb) in which there is enough iron in the body but it is not being utilized correctly to form normal red blood cells. So what causes
