A complete blood count (CBC) provides information about the different types of blood cells. In a person with chronic obstructive pulmonary disease (COPD), the CBC may show:

• An increased number of red blood cells (erythrocytosis). This occurs when the person has had low oxygen levels in the blood (hypoxemia) for a long period of time. Red blood cells carry oxygen in the blood. Because of damage to the lungs, a person with COPD often cannot get enough air. The body reacts by producing more red blood cells to try to increase the amount of oxygen in the blood.
• An increased number of white blood cells.
  • An increase in the white blood cells that fight infection (neutrophils) may mean the person has an infection. An increase in neutrophils can also occur in response to using oral or intravenous (IV) corticosteroids.
  • An increase in the white blood cells that may be produced during an allergic reaction (eosinophils) may indicate that a condition such as asthma is causing the symptoms.

See Complete Blood Count (CBC) for more information on this test.