When diagnosing anemia, a physician will first obtain the patient’s personal and family medical history. The physician will then give the patient a physical examination, listening for a heart murmur and looking for other possible signs of anemia. To help with the diagnosis, the physician will order several blood tests, including:

• Complete blood count (CBC). The CBC includes counts of all three types of blood cells present in a blood sample: red blood cells (RBC), white blood cells (WBC) and platelets (thrombocytes). Anemia is typically confirmed by a low red blood cell count.
  
  
• Hemoglobin count. Hemoglobin is the pigment that carries oxygen on red blood cells and lends the red color to blood cells. Anemia may be diagnosed if the hemoglobin concentration is less than 13.5 grams per milliliter of whole blood (g/dL) in men or 12 g/dL in women.
  
  
• Hematocrit count. A hematocrit count is another way to measure red blood cells by calculating the percent of the blood that is composed of intact red blood cells. A hematocrit count of less than 41 percent in men or 36 percent in women may suggest anemia.

If anemia is present, the physician will next focus on the possible causes. Additional tests may be ordered based on the blood test results:

• If blood tests reveal a low iron level and a low level of ferritin (a protein that stores iron), the physician may order a stool sample to rule out internal bleeding. The physician may also order other gastrointestinal tests, such as an endoscopy.
  
  
• If blood tests reveal a low iron level but a normal ferritin level, then the physician may suspect a chronic illness (e.g., rheumatoid arthritis) that is causing the anemia.
  
  
• If blood tests reveal a normal iron level and a normal ferritin level, then the physician may order additional blood tests to look for a vitamin deficiency.
  
  
• A bone marrow sample may need to be taken to see if the marrow has been replaced by fat cells or cancer cells.
  
  
• A biopsy may be necessary if cancer is suspected, but this is rare.