Hemoglobin is a pigment protein that is found in red blood cells and is measured using a colorimetric method using a fully automated hematocrit analyzer. The normal hemoglobin concentration differs by gender. The normal adult male hemoglobin concentration is 120-160g/L, and the adult female hemoglobin concentration is 110-150g/L. When the hemoglobin concentration decreases, anemia occurs, and the lower the hemoglobin concentration, the more serious the anemia is. When the hemoglobin concentration is lower than 60g/L, it is a severe anemia, and lower than 30g/L is a very severe anemia, which often requires emergency blood transfusion treatment. Increased hemoglobin concentration is commonly seen in patients with increased red blood cell count due to various causes, such as residents of highland areas and long-term chronic hypoxic diseases. Also in patients with true erythrocytosis, an abnormally high hemoglobin concentration can occur.