Hematocrit & Hemoglobin

Hematocrit and hemoglobin measurements are blood tests. They are part of a complete blood count, or CBC. Hematocrit measures the amount of red blood cells that are in blood.

Hemoglobin is a protein-iron compound in the blood that carries oxygen from the lungs to all cells. A hemoglobin test determines how much hemoglobin is in the blood.

Together, the hematocrit and hemoglobin tests help diagnose anemia and polycythemia. Anemia is a shortage of red blood cells due to reduced production of red cells, destruction of red cells, or loss of red cells from internal or external bleeding. Polycythemia is production of too many red blood cells.

These tests require taking a blood sample from the arm. This is a relatively painless procedure that can occur in a clinic, office, hospital, or lab. A nurse or technician wraps a rubber strap tightly around the upper arm. The needle puncture may cause slight discomfort for a moment. For infants, blood is usually taken from a finger or heel.

Occasionally, a small amount of blood collects under the skin at the puncture site. A cool washcloth held against it will help reduce swelling.

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